The Murphy Builders Site

Hello,
If anyone has added bumps for the exhaust on a standard rebel speed
cowling could you please let me know if the filler coat on the cowl
exterior needs to be completely sanded off before glassing on the
additions. By completely, I mean only where the new glass will be stuck
on. I will be using an epoxy resin to secure the glass to the cowl. The
filler coat is quite thick. Does anyone know what material it is? The
elevator and rudder tips have the same filler coating. I glassed on the
ends of the tips without removing the coating. Do you think this will be
a problem? It seems to have adhered very well. I have laid up a couple
of test pieces to see how they will survive a destructive test but I
don't Know what the long term effects will be. My first test has a 2"
square area bonded to the filler coat without any preparation other than
wiping clean with solvent.
The second test piece has the filler coat sanded with 180 grit paper but
not sanded down to the base fiberglass. Also a 2" square patch. In the
third test, I sanded right down to the fiberglass and boned the patch to
it. All patches have an epoxied end with a hole in it so that I can pull
on it with a scale attached. This will establish some data with a peel
strength relating to the preparation of the surface. I am not sure what
will be an acceptable number and it seems that the one bonded directly
to the fiberglass should be the strongest.
Thanks,
Rick D.
Good luck, you'll need it.




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HI Rick
Don't know, can't help you. However if it is the gray primer one often
sees on fibreglass parts it is often a polyester filler such as
featherfill. If that is the case it is not as strong and I think
relatively absorbent/transparent? to water compared to epoxy. One clue
is that if it is polyester it will sand off fairly easy compared to
epoxy primer.
Ken

Rick DeCiero wrote:

Hello,
If anyone has added bumps for the exhaust on a standard rebel speed
cowling could you please let me know if the filler coat on the cowl
exterior needs to be completely sanded off before glassing on the
additions. By completely, I mean only where the new glass will be stuck
on. I will be using an epoxy resin to secure the glass to the cowl. The
filler coat is quite thick. Does anyone know what material it is? The
elevator and rudder tips have the same filler coating. I glassed on the
ends of the tips without removing the coating. Do you think this will be
a problem? It seems to have adhered very well. I have laid up a couple
of test pieces to see how they will survive a destructive test but I
don't Know what the long term effects will be. My first test has a 2"
square area bonded to the filler coat without any preparation other than
wiping clean with solvent.
The second test piece has the filler coat sanded with 180 grit paper but
not sanded down to the base fiberglass. Also a 2" square patch. In the
third test, I sanded right down to the fiberglass and boned the patch to
it. All patches have an epoxied end with a hole in it so that I can pull
on it with a scale attached. This will establish some data with a peel
strength relating to the preparation of the surface. I am not sure what
will be an acceptable number and it seems that the one bonded directly
to the fiberglass should be the strongest.

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On 6/19/02 8:36 AM, RSDEC1@STAR.NET wrote to MURPHY-REBEL:

-> Hello,
-> If anyone has added bumps for the exhaust on a standard rebel speed
-> cowling could you please let me know if the filler coat on the cowl
-> exterior needs to be completely sanded off before glassing on the
-> additions. By completely, I mean only where the new glass will be stuck
-> on. I will be using an epoxy resin to secure the glass to the cowl. The
-> filler coat is quite thick. Does anyone know what material it is? The
-> elevator and rudder tips have the same filler coating. I glassed on the
-> ends of the tips without removing the coating. Do you think this will be
-> a problem? It seems to have adhered very well. I have laid up a couple
-> of test pieces to see how they will survive a destructive test but I
-> don't Know what the long term effects will be. My first test has a 2"
-> square area bonded to the filler coat without any preparation other than
-> wiping clean with solvent.
-> The second test piece has the filler coat sanded with 180 grit paper but
-> not sanded down to the base fiberglass. Also a 2" square patch. In the
-> third test, I sanded right down to the fiberglass and boned the patch to
-> it. All patches have an epoxied end with a hole in it so that I can pull
-> on it with a scale attached. This will establish some data with a peel
-> strength relating to the preparation of the surface. I am not sure what
-> will be an acceptable number and it seems that the one bonded directly
-> to the fiberglass should be the strongest.
-> Thanks,
-> Rick D.
-> Good luck, you'll need it.
->

Hello Rick:

Sorry for the delay in getting back to you. I have been away from email for some time and am playing catch up.

I typically use 36 or 40 grit sandpaper to rough up the area you will be glassing. Sand all of the top coat, primer and gelcoat down to the
fibers (I usually sand a minimum of 1 inch overlap area where the new cloth will be laid down). Be careful sanding and you will be able to
see the fibers start to appear. Do not disturb the fibers too much with the sanding. Vacuum the dust and wipe with a clean cloth. I brush a
very light coat of pure epoxy on the prepared surface to fill the weave and any other micro voids. Once this is accomplished, you are ready
for final layup and glassing. At least that

Terry,
Thanks for the input. I went online and checked out some fiberglassing sites. They all said the basically the same as you have suggested.
One of the best tips that I tried out was to layup several layers of wet glass cloth between two sheets of plastic and squegee out the excess.
Once this is done you cut out the whole sandwich to the shape that you mark on the back side of the plastic. Low mess factor using this method.

Thanks,
Rick D.
Rebel S/N 404R

terry.dazey@dcsol.com wrote:

[quote]On 6/19/02 8:36 AM, RSDEC1@STAR.NET wrote to MURPHY-REBEL:

-> Hello,
-> If anyone has added bumps for the exhaust on a standard rebel speed
-> cowling could you please let me know if the filler coat on the cowl
-> exterior needs to be completely sanded off before glassing on the
-> additions. By completely, I mean only where the new glass will be stuck
-> on. I will be using an epoxy resin to secure the glass to the cowl. The
-> filler coat is quite thick. Does anyone know what material it is? The
-> elevator and rudder tips have the same filler coating. I glassed on the
-> ends of the tips without removing the coating. Do you think this will be
-> a problem? It seems to have adhered very well. I have laid up a couple
-> of test pieces to see how they will survive a destructive test but I
-> don't Know what the long term effects will be. My first test has a 2"
-> square area bonded to the filler coat without any preparation other than
-> wiping clean with solvent.
-> The second test piece has the filler coat sanded with 180 grit paper but
-> not sanded down to the base fiberglass. Also a 2" square patch. In the
-> third test, I sanded right down to the fiberglass and boned the patch to
-> it. All patches have an epoxied end with a hole in it so that I can pull
-> on it with a scale attached. This will establish some data with a peel
-> strength relating to the preparation of the surface. I am not sure what
-> will be an acceptable number and it seems that the one bonded directly
-> to the fiberglass should be the strongest.
-> Thanks,
-> Rick D.
-> Good luck, you'll need it.
->

Hello Rick:

Sorry for the delay in getting back to you. I have been away from email for some time and am playing catch up.

I typically use 36 or 40 grit sandpaper to rough up the area you will be glassing. Sand all of the top coat, primer and gelcoat down to the
fibers (I usually sand a minimum of 1 inch overlap area where the new cloth will be laid down). Be careful sanding and you will be able to
see the fibers start to appear. Do not disturb the fibers too much with the sanding. Vacuum the dust and wipe with a clean cloth. I brush a
very light coat of pure epoxy on the prepared surface to fill the weave and any other micro voids. Once this is accomplished, you are ready
for final layup and glassing. At least that

on 6/22/02 9:04 AM, Rick DeCiero at rsdec1@star.net wrote:

Terry,
Thanks for the input. I went online and checked out some fiberglassing sites.
They all said the basically the same as you have suggested.
One of the best tips that I tried out was to layup several layers of wet glass
cloth between two sheets of plastic and squegee out the excess.

Yes Rick. Sorry, I wasn't sure what exactly you were doing so I abbreviated
my explanation.

When I was building my Long-EZ and doing multiple ply layups, I would get
some brown (heavy) paper (about as thick as a paper bag). I would draw the
cut lines on the bag with a black felt pen. I would then do multiple layups
on top of the paper. Once the cloth was completely "wetted out", I would cut
on the previously drawn black lines (good Weiss scissors needed). Once the
layup was cut to size, I would take the whole mess (paper and all) and flop
it on the part (paper side out). Now, carefully (slowly), get a corner
started with the paint brush (between the paper and the cloth) and slowly
peel the paper backing from the plys, stippling the cloth as I go. Make sure
you carefully stipple ALL of the bubbles out. If I am having problems
chasing the bubbles out, I will occasionally use a hair dryer (CAREFULLY!)
and "warm" the area (NOT hot) and stipple some more.

Hope this helps.

Sounds like you are getting close! Keep us posted.

Your Pilot Pal,

Terry Dazey
Rebel 662






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