Fiberglassing Techniques


Jon Finley <finley@...>
 

I have seen layups use both techniques. The Q plans call for the micro to
be wet (not dry) when you apply the glass. The EZ community has done a lot
of experimentation with what they call "hard shelling." They cut the cores,
sand them, apply micro, sand it, and then apply the glass. The idea is that
the micro can be sanded to achieve a near perfect contour before applying
the glass. It also results in an easy layup (generally) and is much, much
easier to get all the air out. To be clear: I am not talking about applying
micro to low spots in the core or repairing core damage. I am talking about
applying a micro shell around the core before applying the glass.

I have always understood that the purpose of micro is to provide some "bite"
into the foam (like little fingers going into the foam). The foam (if
properly prepared) is smooth and contoured already it just has lots of
little holes in it.

Yes, the quality of the bond was an issue. The conclusion was that the
glass to (dry) micro bond is a lot stronger than the micro to foam bond is
so it is not a concern. This was tested by quite a few folks with different
techniques but the result was always the same. Peeling the glass up always
pulled the micro and bits of foam with it. You could reference CSA back
issues for details.

My personal conclusion (from reading and doing a hard shell layup) was that
I would never do another wet micro layout as the "hard shell" layup is so
much easier. I just glassed my replacement tail cone and didn't want to
have to hangar warm for several days (day or two for micro to cure and then
another day or two for glass to cure) so I did a "traditional" (per Q plans)
layup. I now remember exactly why I decided to use the hard shell
technique!

If you are a "follow the plans" guy, disregard everything I have said and
FOLLOW THE PLANS!!
Jon Finley
Q1 N54JF - 1835cc VW
Q2 N90MG - Subaru EA-81 DD Turbo
Apple Valley, MN

-----Original Message-----
From: Chris McAtee [mailto:Subcanis@...]
Sent: December 06, 2000 8:44 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Questions questions


Dave-
Yes, you do need the to sand the micro before you add the glass. The
micro,
from what I understand, just makes the surface more true in reguards to
smoothness and contour, resulting in less post-glass filling in.

Chris McAtee

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Jon Finley <finley@...>
 

Oh yea, as I recall the weight penalty on large items (wings, winglets) was
pretty small. Seems like the big items weighed a pound or two more when
hard shelled. Again, see CSA back issues for details/confirmation.

Jon

-----Original Message-----
From: Jon Finley [mailto:finley@...]
Sent: December 06, 2000 11:10 AM
To: Q-LIST@...
Subject: RE: [Q-LIST] Fiberglassing Techniques


I have seen layups use both techniques. The Q plans call for the micro to
be wet (not dry) when you apply the glass. The EZ community has done a
lot
of experimentation with what they call "hard shelling." They cut the
cores,
sand them, apply micro, sand it, and then apply the glass. The idea is
that
the micro can be sanded to achieve a near perfect contour before applying
the glass. It also results in an easy layup (generally) and is much, much
easier to get all the air out. To be clear: I am not talking about
applying
micro to low spots in the core or repairing core damage. I am talking
about
applying a micro shell around the core before applying the glass.

I have always understood that the purpose of micro is to provide some
"bite"
into the foam (like little fingers going into the foam). The foam (if
properly prepared) is smooth and contoured already it just has lots of
little holes in it.

Yes, the quality of the bond was an issue. The conclusion was that the
glass to (dry) micro bond is a lot stronger than the micro to foam bond is
so it is not a concern. This was tested by quite a few folks with
different
techniques but the result was always the same. Peeling the glass up always
pulled the micro and bits of foam with it. You could reference CSA back
issues for details.

My personal conclusion (from reading and doing a hard shell layup) was
that
I would never do another wet micro layout as the "hard shell" layup is so
much easier. I just glassed my replacement tail cone and didn't want to
have to hangar warm for several days (day or two for micro to cure and
then
another day or two for glass to cure) so I did a "traditional" (per Q
plans)
layup. I now remember exactly why I decided to use the hard shell
technique!

If you are a "follow the plans" guy, disregard everything I have said and
FOLLOW THE PLANS!!
Jon Finley
Q1 N54JF - 1835cc VW
Q2 N90MG - Subaru EA-81 DD Turbo
Apple Valley, MN




-----Original Message-----
From: Chris McAtee [mailto:Subcanis@...]
Sent: December 06, 2000 8:44 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Questions questions


Dave-
Yes, you do need the to sand the micro before you add the glass. The
micro,
from what I understand, just makes the surface more true in reguards to
smoothness and contour, resulting in less post-glass filling in.

Chris McAtee


____________________________________________________________________________
_________
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http://explorer.msn.com



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David J. Gall
 

Jon,

I must have missed this item. Did RAF ever endorse the hard-shell procedure?
If not, did they ever renounce it? Either way, can you narrow down the
approximate year in either the CSA or RAF newsletter so I don't have to dig
so deep?

On a related issue, I do recall the big debate over sprinkling micro on the
surface of a still-wet layup to save on post-cure filling and sanding. Do
you have an opinion on that technique?

Thanks,


David J. Gall

----- Original Message -----
From: Jon Finley
To: Q-LIST@...
Sent: Wednesday, December 06, 2000 12:13 PM
Subject: RE: [Q-LIST] Fiberglassing Techniques


Oh yea, as I recall the weight penalty on large items (wings, winglets) was
pretty small. Seems like the big items weighed a pound or two more when
hard shelled. Again, see CSA back issues for details/confirmation.

Jon
-----Original Message-----
From: Jon Finley [mailto:finley@...]
Sent: December 06, 2000 11:10 AM
To: Q-LIST@...
Subject: RE: [Q-LIST] Fiberglassing Techniques


I have seen layups use both techniques. The Q plans call for the micro to
be wet (not dry) when you apply the glass. The EZ community has done a
lot
of experimentation with what they call "hard shelling." They cut the
cores,
sand them, apply micro, sand it, and then apply the glass. The idea is
that
the micro can be sanded to achieve a near perfect contour before applying
the glass. It also results in an easy layup (generally) and is much, much
easier to get all the air out. To be clear: I am not talking about
applying
micro to low spots in the core or repairing core damage. I am talking
about
applying a micro shell around the core before applying the glass.

I have always understood that the purpose of micro is to provide some
"bite"
into the foam (like little fingers going into the foam). The foam (if
properly prepared) is smooth and contoured already it just has lots of
little holes in it.

Yes, the quality of the bond was an issue. The conclusion was that the
glass to (dry) micro bond is a lot stronger than the micro to foam bond is
so it is not a concern. This was tested by quite a few folks with
different
techniques but the result was always the same. Peeling the glass up always
pulled the micro and bits of foam with it. You could reference CSA back
issues for details.

My personal conclusion (from reading and doing a hard shell layup) was
that
I would never do another wet micro layout as the "hard shell" layup is so
much easier. I just glassed my replacement tail cone and didn't want to
have to hangar warm for several days (day or two for micro to cure and
then
another day or two for glass to cure) so I did a "traditional" (per Q
plans)
layup. I now remember exactly why I decided to use the hard shell
technique!

If you are a "follow the plans" guy, disregard everything I have said and
FOLLOW THE PLANS!!
Jon Finley
Q1 N54JF - 1835cc VW
Q2 N90MG - Subaru EA-81 DD Turbo
Apple Valley, MN




-----Original Message-----
From: Chris McAtee [mailto:Subcanis@...]
Sent: December 06, 2000 8:44 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Questions questions


Dave-
Yes, you do need the to sand the micro before you add the glass. The
micro,
from what I understand, just makes the surface more true in reguards to
smoothness and contour, resulting in less post-glass filling in.

Chris McAtee


____________________________________________________________________________
_________
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http://explorer.msn.com



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John Loram <johnl@...>
 

Hello Jon:

Boy!, having done only the "wet micro" lay-ups, what you say seems counter
intuitive to me...

In what way is the "dry micro" lay-up easier/faster/better? You mention the
ease of air removal, but it sound to me that the process you describe just
adds another time consuming step; that of the sanding the hardened micro
shell to contour. Do not the multiple layers of fiber glass, on top of the
carefully contoured micro shell, just destroy all the careful contouring
work you've done?.

Seems to me that once the fiber glass is down, you just have to do it all
that careful contouring again. Or, even if the fiberglassing does not change
the contour of the micro shell, would you not still have to go through the
process finishing the surface of the glass in which you accomplish both the
filling and final contouring in a single operation?

Please explain, more! I know for your comment, " I now remember exactly why
I decided to use the hard shell
technique!", that I'm missing something.......

thanks, -john-

-----Original Message-----
From: Jon Finley [mailto:finley@...]
Sent: Wednesday, December 06, 2000 9:10 AM
To: Q-LIST@...
Subject: RE: [Q-LIST] Fiberglassing Techniques


I have seen layups use both techniques. The Q plans call for the micro to
be wet (not dry) when you apply the glass. The EZ community has done a lot
of experimentation with what they call "hard shelling." They cut the cores,
sand them, apply micro, sand it, and then apply the glass. The idea is that
the micro can be sanded to achieve a near perfect contour before applying
the glass. It also results in an easy layup (generally) and is much, much
easier to get all the air out. To be clear: I am not talking about applying
micro to low spots in the core or repairing core damage. I am talking about
applying a micro shell around the core before applying the glass.

I have always understood that the purpose of micro is to provide some "bite"
into the foam (like little fingers going into the foam). The foam (if
properly prepared) is smooth and contoured already it just has lots of
little holes in it.

Yes, the quality of the bond was an issue. The conclusion was that the
glass to (dry) micro bond is a lot stronger than the micro to foam bond is
so it is not a concern. This was tested by quite a few folks with different
techniques but the result was always the same. Peeling the glass up always
pulled the micro and bits of foam with it. You could reference CSA back
issues for details.

My personal conclusion (from reading and doing a hard shell layup) was that
I would never do another wet micro layout as the "hard shell" layup is so
much easier. I just glassed my replacement tail cone and didn't want to
have to hangar warm for several days (day or two for micro to cure and then
another day or two for glass to cure) so I did a "traditional" (per Q plans)
layup. I now remember exactly why I decided to use the hard shell
technique!

If you are a "follow the plans" guy, disregard everything I have said and
FOLLOW THE PLANS!!
Jon Finley
Q1 N54JF - 1835cc VW
Q2 N90MG - Subaru EA-81 DD Turbo
Apple Valley, MN




-----Original Message-----
From: Chris McAtee [mailto:Subcanis@...]
Sent: December 06, 2000 8:44 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Questions questions

Dave-
Yes, you do need the to sand the micro before you add the glass. The
micro,
from what I understand, just makes the surface more true in reguards to
smoothness and contour, resulting in less post-glass filling in.

Chris McAtee

____________________________________________________________________________
_________
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http://explorer.msn.com



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Cash, Gene <CASH@...>
 

I read something ages ago saying that Rutan (RAF) clearly poo-pooed the
practice of sprinkling microballoons on wet lay-ups because it would tend to
pull up epoxy and starve the lower layers of needed adhesive. For the same
reason the practice of laying peel-ply over the entire wing surface lay-up
was nixed.

There doesn't seem to be an easy way out of the surface finish work.

Gene Cash

-----Original Message-----
From: David J. Gall [SMTP:David@...]
Sent: Wednesday, December 06, 2000 9:38 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Fiberglassing Techniques

Jon,

I must have missed this item. Did RAF ever endorse the hard-shell
procedure?
If not, did they ever renounce it? Either way, can you narrow down the
approximate year in either the CSA or RAF newsletter so I don't have to
dig
so deep?

On a related issue, I do recall the big debate over sprinkling micro on
the
surface of a still-wet layup to save on post-cure filling and sanding. Do
you have an opinion on that technique?

Thanks,


David J. Gall

----- Original Message -----
From: Jon Finley
To: Q-LIST@...
Sent: Wednesday, December 06, 2000 12:13 PM
Subject: RE: [Q-LIST] Fiberglassing Techniques


Oh yea, as I recall the weight penalty on large items (wings, winglets)
was
pretty small. Seems like the big items weighed a pound or two more when
hard shelled. Again, see CSA back issues for details/confirmation.

Jon
-----Original Message-----
From: Jon Finley [mailto:finley@...]
Sent: December 06, 2000 11:10 AM
To: Q-LIST@...
Subject: RE: [Q-LIST] Fiberglassing Techniques


I have seen layups use both techniques. The Q plans call for the micro
to
be wet (not dry) when you apply the glass. The EZ community has done a
lot
of experimentation with what they call "hard shelling." They cut the
cores,
sand them, apply micro, sand it, and then apply the glass. The idea is
that
the micro can be sanded to achieve a near perfect contour before
applying
the glass. It also results in an easy layup (generally) and is much,
much
easier to get all the air out. To be clear: I am not talking about
applying
micro to low spots in the core or repairing core damage. I am talking
about
applying a micro shell around the core before applying the glass.

I have always understood that the purpose of micro is to provide some
"bite"
into the foam (like little fingers going into the foam). The foam (if
properly prepared) is smooth and contoured already it just has lots of
little holes in it.

Yes, the quality of the bond was an issue. The conclusion was that the
glass to (dry) micro bond is a lot stronger than the micro to foam bond
is
so it is not a concern. This was tested by quite a few folks with
different
techniques but the result was always the same. Peeling the glass up
always
pulled the micro and bits of foam with it. You could reference CSA back
issues for details.

My personal conclusion (from reading and doing a hard shell layup) was
that
I would never do another wet micro layout as the "hard shell" layup is
so
much easier. I just glassed my replacement tail cone and didn't want to
have to hangar warm for several days (day or two for micro to cure and
then
another day or two for glass to cure) so I did a "traditional" (per Q
plans)
layup. I now remember exactly why I decided to use the hard shell
technique!

If you are a "follow the plans" guy, disregard everything I have said
and
FOLLOW THE PLANS!!
Jon Finley
Q1 N54JF - 1835cc VW
Q2 N90MG - Subaru EA-81 DD Turbo
Apple Valley, MN




-----Original Message-----
From: Chris McAtee [mailto:Subcanis@...]
Sent: December 06, 2000 8:44 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Questions questions


Dave-
Yes, you do need the to sand the micro before you add the glass. The
micro,
from what I understand, just makes the surface more true in reguards
to
smoothness and contour, resulting in less post-glass filling in.

Chris McAtee


__________________________________________________________________________
__
_________
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http://explorer.msn.com



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Jon Finley <finley@...>
 

Hi David,

I don't recall what RAF had to say about it, I would certainly think one of
those guys asked. It was at least a couple years ago. I will see if I can
lay my hands on them tonight and let you know.

I use the "bubble sprinkle" somewhat differently than maybe what you are
thinking. I use it to eliminate the glossy surface on the layup so that the
dry micro applies easier and has a surface to grip. So the only sanding that
is minimized/eliminated is that required to remove the gloss and create
something for the micro to grip, filling is still required. With this in
mind, I believe that the bubbles should be applied just before the epoxy
tackiness goes away and that only a very small quantity of bubbles be
applied. The goal is is to have the bubbles stick but not absorb epoxy. I
usually sprinkle the bubbles on, rub it in with my gloved hand (if this
helps understand when I do it - the epoxy is pretty set), and then brush off
the excess bubbles (the ones not sticking). I have never done it with a
large/structural layup (haven't had the opportunity). I'm of the opinion
that if the layup isn't dry and the builder waits until the right stage, it
is ok. I can imagine someone pouring a couple gallons of bubbles on a wet
layup, obviously this isn't going to work real well (probably result in an
extremely dry layup with a ton of sanding needed (before throwing away)).
The big problem with doing this is that layup inspection is very difficult
after applying the bubbles, you really need to inspect the layup before
applying the bubbles.

As long as we are talking about stuff that is "wild & crazy".... I also
use alcohol to thin my dry micro. I mix up the micro as dry as possible,
add a small amount of alcohol (I do it by eye, but it is probably a
tablespoon or so for an 8-12 oz cup of micro), and then add more bubbles.
The result is an extremely light micro that is easier to spread. Yea, there
was a big debate about this too (does the alcohol mess with the chemical
properties of the epoxy, etc...). All I know for sure is that all of the
airplanes that I know were finished this way and they still look fine.

Jon Finley
Q1 N54JF - 1835cc VW
Q2 N90MG - Subaru EA-81 DD Turbo
Apple Valley, Minnesota

-----Original Message-----
From: David J. Gall [mailto:David@...]
Sent: December 06, 2000 11:38 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Fiberglassing Techniques


Jon,

I must have missed this item. Did RAF ever endorse the hard-shell
procedure?
If not, did they ever renounce it? Either way, can you narrow down the
approximate year in either the CSA or RAF newsletter so I don't have to
dig
so deep?

On a related issue, I do recall the big debate over sprinkling micro on
the
surface of a still-wet layup to save on post-cure filling and sanding. Do
you have an opinion on that technique?

Thanks,


David J. Gall


Dave King <KingDWS@...>
 

Hi

When I wrote the question I was using my little Tosh notebook, little keys
big fingers, slow typing.
I'm back on my regular machine so that means lots of typlexia and bad
spelling...;-]

What I didn't add to the original question was that I was looking at this
with an eye towards
getting a perfect contour to start with and if this helps with the final
finish ie more accurate or
less finishing required etc.

Oh yea, as I recall the weight penalty on large items (wings, winglets) was
pretty small. Seems like the big items weighed a pound or two more when
hard shelled. Again, see CSA back issues for details/confirmation.
I take it this is Ez sized wings? I don't have CSA but I did a search through
my cp's and couldn't find a reference in there (I'm sure it is somewhere).
From what I was told it was supposed to result in a lighter layup as the
cured micro layer sealed the foam from any fresh epoxy getting into the
pores. I can see how it might come out the same weight or heavier but
wasn't too sure about lighter.

I have seen layups use both techniques. The Q plans call for the micro to
be wet (not dry) when you apply the glass. The EZ community has done a
lot of experimentation with what they call "hard shelling." SNIP
I hadn't heard it called hard shelling so I'll do some searching on that.
From the info I had the core was finished then micro slurry applied and
squeeged normally but allowed to cure. Then any dimples dents etc are filled,
ie scuffed land then filled and allowed to cure. Then the micro 'd core gets
sanded down using reversed templates to check contour. The rest of the prep
is the same as a glass to glass. Then the cloth gets laid up as per normal.
From what I saw of this it should give a good base to start with and if the
layups
are done with care the final finish is more accurate.

Yes, the quality of the bond was an issue. The conclusion was that the
glass to (dry) micro bond is a lot stronger than the micro to foam bond is
so it is not a concern. This was tested by quite a few folks with
different
techniques but the result was always the same. Peeling the glass up always
pulled the micro and bits of foam with it. You could reference CSA back
issues for details.
If the foam came up then its definalty failing in the right way. Sounds
good.
To me it seems that it couldn't be any weaker than a glass to glass bond
done over time. ie one layer applied after the epoxy has cured.

My personal conclusion (from reading and doing a hard shell layup) was
that I would never do another wet micro layout as the "hard shell" layup
is so
much easier.
Thats interesting to as I kept thinking it would be a bit more work in the
long run.

If you are a "follow the plans" guy, disregard everything I have said and
FOLLOW THE PLANS!!
PLANS??? We don't need no steenkin plans!! (quickly donning flame proof
underwear)

Cheers

Dave


Bruce Crain
 

If you use denatured alcohol to thin the "dry micro" for finishing, the
foam will not erode. My 2 cents worth.
Bruce Crain


On Wed, 6 Dec 2000 12:26:46 -0600 "Jon Finley" <finley@...>
writes:
Hi David,

I don't recall what RAF had to say about it, I would certainly think
one of
those guys asked. It was at least a couple years ago. I will see if
I can
lay my hands on them tonight and let you know.

I use the "bubble sprinkle" somewhat differently than maybe what you
are
thinking. I use it to eliminate the glossy surface on the layup so
that the
dry micro applies easier and has a surface to grip. So the only
sanding that
is minimized/eliminated is that required to remove the gloss and
create
something for the micro to grip, filling is still required. With this
in
mind, I believe that the bubbles should be applied just before the
epoxy
tackiness goes away and that only a very small quantity of bubbles be
applied. The goal is is to have the bubbles stick but not absorb
epoxy. I
usually sprinkle the bubbles on, rub it in with my gloved hand (if
this
helps understand when I do it - the epoxy is pretty set), and then
brush off
the excess bubbles (the ones not sticking). I have never done it with
a
large/structural layup (haven't had the opportunity). I'm of the
opinion
that if the layup isn't dry and the builder waits until the right
stage, it
is ok. I can imagine someone pouring a couple gallons of bubbles on a
wet
layup, obviously this isn't going to work real well (probably result
in an
extremely dry layup with a ton of sanding needed (before throwing
away)).
The big problem with doing this is that layup inspection is very
difficult
after applying the bubbles, you really need to inspect the layup
before
applying the bubbles.

As long as we are talking about stuff that is "wild & crazy".... I
also
use alcohol to thin my dry micro. I mix up the micro as dry as
possible,
add a small amount of alcohol (I do it by eye, but it is probably a
tablespoon or so for an 8-12 oz cup of micro), and then add more
bubbles.
The result is an extremely light micro that is easier to spread. Yea,
there
was a big debate about this too (does the alcohol mess with the
chemical
properties of the epoxy, etc...). All I know for sure is that all of
the
airplanes that I know were finished this way and they still look fine.

Jon Finley
Q1 N54JF - 1835cc VW
Q2 N90MG - Subaru EA-81 DD Turbo
Apple Valley, Minnesota




-----Original Message-----
From: David J. Gall [mailto:David@...]
Sent: December 06, 2000 11:38 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Fiberglassing Techniques


Jon,

I must have missed this item. Did RAF ever endorse the hard-shell
procedure?
If not, did they ever renounce it? Either way, can you narrow down
the
approximate year in either the CSA or RAF newsletter so I don't have
to
dig
so deep?

On a related issue, I do recall the big debate over sprinkling micro
on
the
surface of a still-wet layup to save on post-cure filling and
sanding. Do
you have an opinion on that technique?

Thanks,


David J. Gall







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jtenhave@mets.mq.edu.au <jtenhave@...>
 

Dave,

there are a couple of reasons why the hard shelling technique is not optimum.

They are:

1. When sanding the shell, the difference in resistance to sanding between micro and foam is
so great that the moment you break through the shell you have stuffed the contour and you
are up for a repair anyway.

2. You deny yourself the advantage of a chemical bond between the micro and the glass

3. Foam is much, much easier to sand than micro therefore it is much easier to get a near
perfect core with bare foam. ( i.e. long sanding blocks and sanding templates)

4 The near perfect contour you go to such lengths to generate is inevitably disrupted the
moment you layup any varying thicknesses of glass on the foam surface (unless you
read ahead and make the appropriate allowances in the foam) so you are up for surface
filling whichever way you look at it.

5 It doesn't make a great deal of sense to make one simple operation into two or more
for no overall benefit.


Hope this helps

John

-----Original Message-----
From: Dave King [SMTP:KingDWS@...]
Sent: Thursday, December 07, 2000 8:23 AM
To: Q-LIST@...
Subject: RE: [Q-LIST] Fiberglassing Techniques


Hot Wings
 

Just another opinion and a look at this from a different perspective - It's
left up to the reader to glean the truth.

<< 1. When sanding the shell, the difference in resistance to sanding between
micro and foam is
so great that the moment you break through the shell you have stuffed the
contour and you
are up for a repair anyway.

I have not found this to be a problem unless the core was way too wavy to
start with. If you sand only until you see a blue (or orange) pattern appear
that looks like a dried up lake bed you still have several thousandths of
micro left to keep your sanding block from digging into the foam.

2. You deny yourself the advantage of a chemical bond between the micro and
the glass

This is a moot point as a clean and sanded epoxy/epoxy bond is many times
stronger than the foam/foam bond. The foam will ALWAYS fail first.

3. Foam is much, much easier to sand than micro therefore it is much easier
to get a near
perfect core with bare foam. ( i.e. long sanding blocks and sanding
templates)

Its so much easier to sand that it takes a really light touch not to
damage the foam. I find that it takes me less time to sand a good contour
with the "skin" even though it takes more "work".

4 The near perfect contour you go to such lengths to generate is inevitably
disrupted the
moment you lay-up any varying thicknesses of glass on the foam surface
(unless you
read ahead and make the appropriate allowances in the foam) so you are up
for surface
filling whichever way you look at it.

Aren't we supposed to "plan ahead"? About the only area where I have
found a problem with loosing the contour is on the leading edge of the wing
where lay-ups over lap. Other than this after several layers of (carefully
laid) glass have cured a long block will still evenly mark the surface just
as it did before the glassing. If the lay-ups are done carefully many times
all the prep that is needed is a sanding with 220 and a coat of primer/sealer.

5 It doesn't make a great deal of sense to make one simple operation into
two or more
for no overall benefit.
>>
Very true - But I do see a 2 very real over all benefits. 1); I think
you get a STRONGER wing because as we all know the limiting factor is the
compression strength of the materials we are working with and I find the
glass fibers to lay much straighter when layed up on a flat and firm surface
rather than over some squishy micro which always seems to move around when
working the lay-up. And 2); I find it requires less over all work to get to
the finished product.

If in doubt - do it by the plans. We know they work.

"Think outside the box - but fly in the envelope"
<A HREF="http://hometown.aol.com/bd5er/Qpage.html">Q-2 page</A>
Leon McAtee


jtenhave@mets.mq.edu.au <jtenhave@...>
 

Gene,

This process straight onto the glass was discouraged because the assumption was that the original
layup was optimal i.e. the minimum amount of resin was used to just wet out
the glass cloth. By definition therefore, anything that drew resin from an optimised
layup would result in a lean top laminate.

The solution was to wait until the layup had gelled and then spread the minimum
amount of micro over that surface, a reasonably wet mix makes the spreading of a
thin layer much easier. At this stage you can sprinkle micro to your hearts content
which will result in the leaning out of the wet micro mix and a much easier layup.

I would like to be able to take the claps for this, but I learnt this technique whilst working
with Dave Ronneburg building the prototype Berkut. One caveat is that this
process denies you the opportunity to inspect the skin to whatever bonds after
cure, but in Berkut's case, the skins were carbon so it was academic. If this is a
concern, those sub surface bond areas could be left bare.

Peel plying was discouraged for another reason. It was claimed that this would
add weight because the added resin would be used to fill the peaks and troughs
between each bundle of fibers in the cloth and if used in that way, there is no
doubt there is a weight penalty. The original design calcs are based on the
assumption that the top skin will be sanded flat, i.e. that half the bundles will be
damaged getting down to the required condition for bonding and finishing. Then
the micro finishing process is carried out, filling up the remaining texture and
the transitions between layers of glass

There is however, another way to look at peelplying. If the top layer is applied slightly
rich resinwise, and then peelplyed three things happen. The first is that the surface
finish requires little or no sanding prior to bonding, microing and much less filler.
The second advantage is that any sanding does much less damage to the structural
glass. The third advantage is that the glass bundles are pressed flat and by judicious
squeegeeing most if not all of the excess resin can be removed from the layup.
The savings in sanding when you are at an energetic and resource ebb are significant.

One final caveat is to ensure that the peel ply has no untoward coatings which could
degrade the final bond.

Hope this clarifies the issue.

John

-----Original Message-----
From: Cash, Gene [SMTP:CASH@...]
Sent: Thursday, December 07, 2000 5:09 AM
To: 'Q-LIST@...'
Subject: RE: [Q-LIST] Fiberglassing Techniques

I read something ages ago saying that Rutan (RAF) clearly poo-pooed the
practice of sprinkling microballoons on wet lay-ups because it would tend to
pull up epoxy and starve the lower layers of needed adhesive. For the same
reason the practice of laying peel-ply over the entire wing surface lay-up
was nixed.

There doesn't seem to be an easy way out of the surface finish work.

Gene Cash

-----Original Message-----
From: David J. Gall [SMTP:David@...]
Sent: Wednesday, December 06, 2000 9:38 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Fiberglassing Techniques

Jon,

I must have missed this item. Did RAF ever endorse the hard-shell
procedure?
If not, did they ever renounce it? Either way, can you narrow down the
approximate year in either the CSA or RAF newsletter so I don't have to
dig
so deep?

On a related issue, I do recall the big debate over sprinkling micro on
the
surface of a still-wet layup to save on post-cure filling and sanding. Do
you have an opinion on that technique?

Thanks,


David J. Gall

----- Original Message -----
From: Jon Finley
To: Q-LIST@...
Sent: Wednesday, December 06, 2000 12:13 PM
Subject: RE: [Q-LIST] Fiberglassing Techniques


Oh yea, as I recall the weight penalty on large items (wings, winglets)
was
pretty small. Seems like the big items weighed a pound or two more when
hard shelled. Again, see CSA back issues for details/confirmation.

Jon
-----Original Message-----
From: Jon Finley [mailto:finley@...]
Sent: December 06, 2000 11:10 AM
To: Q-LIST@...
Subject: RE: [Q-LIST] Fiberglassing Techniques


I have seen layups use both techniques. The Q plans call for the micro
to
be wet (not dry) when you apply the glass. The EZ community has done a
lot
of experimentation with what they call "hard shelling." They cut the
cores,
sand them, apply micro, sand it, and then apply the glass. The idea is
that
the micro can be sanded to achieve a near perfect contour before
applying
the glass. It also results in an easy layup (generally) and is much,
much
easier to get all the air out. To be clear: I am not talking about
applying
micro to low spots in the core or repairing core damage. I am talking
about
applying a micro shell around the core before applying the glass.

I have always understood that the purpose of micro is to provide some
"bite"
into the foam (like little fingers going into the foam). The foam (if
properly prepared) is smooth and contoured already it just has lots of
little holes in it.

Yes, the quality of the bond was an issue. The conclusion was that the
glass to (dry) micro bond is a lot stronger than the micro to foam bond
is
so it is not a concern. This was tested by quite a few folks with
different
techniques but the result was always the same. Peeling the glass up
always
pulled the micro and bits of foam with it. You could reference CSA back
issues for details.

My personal conclusion (from reading and doing a hard shell layup) was
that
I would never do another wet micro layout as the "hard shell" layup is
so
much easier. I just glassed my replacement tail cone and didn't want to
have to hangar warm for several days (day or two for micro to cure and
then
another day or two for glass to cure) so I did a "traditional" (per Q
plans)
layup. I now remember exactly why I decided to use the hard shell
technique!

If you are a "follow the plans" guy, disregard everything I have said
and
FOLLOW THE PLANS!!
Jon Finley
Q1 N54JF - 1835cc VW
Q2 N90MG - Subaru EA-81 DD Turbo
Apple Valley, MN




-----Original Message-----
From: Chris McAtee [mailto:Subcanis@...]
Sent: December 06, 2000 8:44 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Questions questions


Dave-
Yes, you do need the to sand the micro before you add the glass. The
micro,
from what I understand, just makes the surface more true in reguards
to
smoothness and contour, resulting in less post-glass filling in.

Chris McAtee


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Pat Panzera <panzera@...>
 

"jtenhave@..." wrote:

Gene,

This process straight onto the glass was discouraged because the assumption was that the original
layup was optimal i.e. the minimum amount of resin was used to just wet out
the glass cloth. By definition therefore, anything that drew resin from an optimised
layup would result in a lean top laminate.
John, not to single out your message, but rather this is to address
this entire thread....

Is there any real proof that raw micro balloons spread over liquid epoxy
could wick material away from where it belongs, or is this another
hanger legend?

If I spilled a bunch of epoxy on my hanger floor, the last thing I would
use to try and absorb it would be micro... even if it were free. If it
were free, I'd reach for flox first. Heck, when I WANT to mix micro
with epoxy it's a serious pain in the rear!

I would almost be willing to bet (almost) that if you mixed some epoxy
and placed a dime size drop on wax paper, then sprinkled micro over
the drop, the surface tension of the liquid would support the weight
of the micro, and only the balloons which are actually in contact with
the liquid would stick after cure.

Additionally, I don't think the optimal ratio of resin to glass can
be achieved by the process outlined in the plans. I believe that the
hand process produces a epoxy rich lay-up, and if a builder ever saw
a lay-up with the exact perfect ratio, he'd swear it was dry.

Therefore I can't see how dusting micro over a completed lay-up could
compromise the structure. In reality, I can see how it can help to
maintain the structure, by reducing the amount of potentially destructive
sanding called for in the step immediately before filling the weave.

BUT!!! If prototype was built with a (presumably) rich mixture, and
we are building knock-off's of the prototype and trusting our lives to
it's flight test information, then in order to be secure in this
information, we need to do it the same way the prototype was done....
or do our own testing.

Pat

I've dusted plenty of parts with a very conservative amount of micro,
and it always seemed that after cure, almost all the micro came
back off, except that which was directly in contact with the epoxy.


jtenhave@mets.mq.edu.au <jtenhave@...>
 

Pat,

Single away, a valid assertion should be able to withstand sceptical questioning!

let me play the devils advocate here, If no micro sticks when sprinkled on a
resin rich surface ( whether or not it contains glass) why bother doing it at all?

I am not advocating this as a practice, merely explaining why it was discouraged.

I have never done it, why? because I thought it was a dumb idea, and at the
time I built my Long Eze I had not heard of the method of wet micro on top of a tacky
layup. Quite apart from the fact that at the end of a wing layup, I had run out of puff....
-and I had peel plied the surface.......

With respect to optimal layups, I would have agreed with you to a large extent prior
to seeing the experts at work, now I know that it is possible to make parts by hand that are
much more efficient...resin wise and the best way of all is under vacuum.

Incidently, optimal layups do not look like dry layups, they are uniform in colour and the
bundles are discrete, hence the difficulty in sanding them to a uniformly scratched finish.

A very good video on the subject is Mike Arnold's tape "How Its Made" describing the construction
of the AR-5. If you are glutton for punishment, his "Making Fiberglass Molds" will cast even greater
light on the subject.

Regards

John

-----Original Message-----
From: Pat Panzera [SMTP:panzera@...]
Sent: Friday, December 08, 2000 12:28 PM
To: Q-LIST@...
Subject: Re: [Q-LIST] Fiberglassing Techniques



"jtenhave@..." wrote:

Gene,

This process straight onto the glass was discouraged because the assumption was that the original
layup was optimal i.e. the minimum amount of resin was used to just wet out
the glass cloth. By definition therefore, anything that drew resin from an optimised
layup would result in a lean top laminate.
John, not to single out your message, but rather this is to address
this entire thread....

Is there any real proof that raw micro balloons spread over liquid epoxy
could wick material away from where it belongs, or is this another
hanger legend?

If I spilled a bunch of epoxy on my hanger floor, the last thing I would
use to try and absorb it would be micro... even if it were free. If it
were free, I'd reach for flox first. Heck, when I WANT to mix micro
with epoxy it's a serious pain in the rear!

I would almost be willing to bet (almost) that if you mixed some epoxy
and placed a dime size drop on wax paper, then sprinkled micro over
the drop, the surface tension of the liquid would support the weight
of the micro, and only the balloons which are actually in contact with
the liquid would stick after cure.

Additionally, I don't think the optimal ratio of resin to glass can
be achieved by the process outlined in the plans. I believe that the
hand process produces a epoxy rich lay-up, and if a builder ever saw
a lay-up with the exact perfect ratio, he'd swear it was dry.

Therefore I can't see how dusting micro over a completed lay-up could
compromise the structure. In reality, I can see how it can help to
maintain the structure, by reducing the amount of potentially destructive
sanding called for in the step immediately before filling the weave.

BUT!!! If prototype was built with a (presumably) rich mixture, and
we are building knock-off's of the prototype and trusting our lives to
it's flight test information, then in order to be secure in this
information, we need to do it the same way the prototype was done....
or do our own testing.

Pat

I've dusted plenty of parts with a very conservative amount of micro,
and it always seemed that after cure, almost all the micro came
back off, except that which was directly in contact with the epoxy.



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jtenhave@mets.mq.edu.au <jtenhave@...>
 

Leon,

thanks for your comments, your points raise some interesting issues which
extend the discussion beyond the scope of the original query - which is a good thing!

In the interests of bandwidth, let me snip that which is not needed to continue the discussion.

I have not found this to be a problem unless the core was way too wavy to
start with. If you sand only until you see a blue (or orange) pattern appear
that looks like a dried up lake bed you still have several thousandths of
micro left to keep your sanding block from digging into the foam.

No argument here apart from why bother with the extra work? If the core
was correct, none of this would be necessary.

Its so much easier to sand that it takes a really light touch not to
damage the foam. I find that it takes me less time to sand a good contour
with the "skin" even though it takes more "work".

So, I might add, would using a lighter grade of paper on ones sanding board.
We are not talking about a great deal of finesse here, just care.


Aren't we supposed to "plan ahead"? About the only area where I have
found a problem with loosing the contour is on the leading edge of the wing
where lay-ups over lap. Other than this after several layers of (carefully
laid) glass have cured a long block will still evenly mark the surface just
as it did before the glassing. If the lay-ups are done carefully many times
all the prep that is needed is a sanding with 220 and a coat of primer/sealer.

I am interested to learn how it was possible to have planned ahead sufficiently
to recess a hard shell for each spar cap laminate, to have permitted the uni skin
to have joggled up and down the .009" steps required for each ply, ( 9 plys from
memory on the Q1 canard) to have accurately predicted and allowed for the tapes
which attach the flying surfaces to the fuselage, and to have allowed for the wing tip
layups, the elevator and aileron slot layups, the wheel pant attachment layups and
still be able to evenly mark the surface with a long block. (I am assuming that the
block is being used spanwise?) Extraordinary stuff!

>>
Very true - But I do see a 2 very real over all benefits. 1); I think
you get a STRONGER wing because as we all know the limiting factor is the
compression strength of the materials we are working with and I find the
glass fibers to lay much straighter when layed up on a flat and firm surface
rather than over some squishy micro which always seems to move around when
working the lay-up.

It is unclear that the limiting factor is the compressive strength of the materials we
use. in the case of our composite It is less than the tensile, but so is the peel strength
and the bearing strength, so what? That is why different layup schedules are used.
The limit is the stress that the part sees, hence the flight envelope and the weight
limit. It is quite unclear why one would get a stronger wing because we all know
the limiting factor is the compression strength....... Perhaps I am missing something here?

I think you will have universal support for the assertion that having the fibers lying straight
is desirable, but it could be that there was too much, too soft micro beneath the layup which was
too wet which permitted the problems described above.

The optimum amount of micro is that which just fills the cells of the foam. Remember that
honeycomb cores have gaps of several millimetres between the edges of the cells. All you
have to do is to provide a bond sufficient to transfer the shear loads carried by the core - as you
rightly pointed out above....it is not a lot.


And 2); I find it requires less over all work to get to
the finished product.

You are right, Leon but the quality of the product may differ. Other than items produced
in a female mold it is hard to think of anything which would achieve the finish specified
in the plans with a 220 grit sand and a coat of primer sealer.


Regards

John


Hot Wings
 

In a message dated 12/7/00 23:20:38 Pacific Standard Time,
jtenhave@... writes:

<< Leon,

thanks for your comments, your points raise some interesting issues which
extend the discussion beyond the scope of the original query - which is a
good thing!
>>
========================
I am so glad that you did not take my post as an attack on your views -
It was definitely not meant as such and I was worried that it would be taken
that way given the history of this group. I have done lay-ups both ways and
I have just found that I am more efficient doing it the "hard shell" way.
Try it, you might like it.
Your observations about planning ahead with regard to the .009" thick
lay-ups for the wing spar caps brings up a question that someone here might
know the answer to. I have always assumed that the factory took the
thickness of these lay-ups into consideration when they made the templates
for hot wiring. Having never lofted the "real" airfoils and compared them to
the factory templates I don't know if this is true or not. While it makes no
real difference one way or the other I would kind of like to know one way or
the other.

"Think outside the box - but fly in the envelope"
<A HREF="http://hometown.aol.com/bd5er/Qpage.html">Q-2 page</A>
Leon McAtee


Pat Panzera <panzera@...>
 

"jtenhave@..." wrote:

<snip>

let me play the devils advocate here, If no micro sticks when sprinkled on a
resin rich surface ( whether or not it contains glass) why bother doing it at all?
It's not that "no" micro sticks, but it's been my experience that only
the thin layer of micro which is in direct contact with the uncured epoxy
sticks.

Take a mixing cup half full of properly mixed (uncured) epoxy, and fill
the balance of the cup with micro, then (with no mixing) walk away and
let it cure. Believing the common theory that sprinkling powdered micro
balloons over a properly wetted out part robs the part of epoxy, one
would assume that when we returned to the test cup, we'd find a large
part of the epoxy has wicked up into the micro.

Not having actually tried this experiment, I believe that when we return
to our cup, we will be able to dump out of the cup, all the micro, save
a very thin layer.

But to answer your question... this thin layer now makes for a highly
suitable surface for applying an additional layer of micro, after a small
amount of light sanding, which may or may not be needed at all.

Thanks!

Pat


jtenhave@mets.mq.edu.au <jtenhave@...>
 

Pat,

I agree with you here, indeed I think that you might even be giving
the micro a better chance to wet out than would be the case with an optimal
layup. I am moving house right now so all my laminating gear and aircraft
projects are packed up, but I will do the experiment and report back.

A peel plied surface would also provide the same preparation for sanding and
filling.

John

-----Original Message-----
From: Pat Panzera [SMTP:panzera@...]
Sent: Saturday, December 09, 2000 7:29 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Fiberglassing Techniques



"jtenhave@..." wrote:

<snip>

let me play the devils advocate here, If no micro sticks when sprinkled on a
resin rich surface ( whether or not it contains glass) why bother doing it at all?
It's not that "no" micro sticks, but it's been my experience that only
the thin layer of micro which is in direct contact with the uncured epoxy
sticks.

Take a mixing cup half full of properly mixed (uncured) epoxy, and fill
the balance of the cup with micro, then (with no mixing) walk away and
let it cure. Believing the common theory that sprinkling powdered micro
balloons over a properly wetted out part robs the part of epoxy, one
would assume that when we returned to the test cup, we'd find a large
part of the epoxy has wicked up into the micro.

Not having actually tried this experiment, I believe that when we return
to our cup, we will be able to dump out of the cup, all the micro, save
a very thin layer.

But to answer your question... this thin layer now makes for a highly
suitable surface for applying an additional layer of micro, after a small
amount of light sanding, which may or may not be needed at all.

Thanks!

Pat



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Mike Dwyer <mdwyer@...>
 

I thought it was pretty easy to lay down the micro then the glass per the
plans. I wouldn't waste the time for the two extra steps of micro&sand.

Just my opinion.
Mike
Q-200 built in 16 months


Pat Panzera <panzera@...>
 

"jtenhave@..." wrote:

Pat,

I agree with you here, indeed I think that you might even be giving
the micro a better chance to wet out than would be the case with an optimal
layup. I am moving house right now so all my laminating gear and aircraft
projects are packed up, but I will do the experiment and report back.

A peel plied surface would also provide the same preparation for sanding and
filling.
A peel plied surface would he heavier, as all the void
space between
the threads would be filled with 100% epoxy. Additionally,
sanding
would be a serious drag, and would be necessary as there's
hardly a
good way to lay peel ply on a compound curved surface
without it wrinkling
and trapping high spots of pure epoxy.

On another note, as for placing 10oz bid directly over
uncured micro
(as the plans call for) I've had a bit of trouble keeping
the micro
from oozing (even if only a little bit) between the fibers
as I wet out
the first layer of glass, and therefore micro ends up
between the layers
of glass.

Pat