R

RV7ADRIVER

I'm New Here
I am building a 7A.
The inside of the engine cowl has what looks like a thin layer of fiberglass over the honeycomb.
It looks and feel porous.
I'm thinking this should be sealed.
Has anyone painted on a thin layer of epoxy resin?
Does that crack or flake off over time?
How does the 50% epoxy resin and 50% acetone mixture mentioned in the builders instructions for filling pin holes work out?
High temp paint is an option but what a pain to remove if a repair is needed.
Any experience with this is helpful.
Thanks in advance.
 
Dont bother sealing it. The rough surface you feel is from peel ply. The cowling is obviously vacuum bagged and peel ply leaves a nice finish. I found mine cleans right up with a bit of degreaser at service time.

Some do paint etc, but I just see it as adding weight. If you paint it with epoxy it will stick very well. That is what peel ply does [prepare surface]
 
I would seal it. The rough peel ply surface will also retain the inevitable oil and that will catch dust. Prime and paint and it will be much easier to keep clean.
 
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funny you should ask, i am doing this right now. i painted the inside with akzo. as far as thinning epoxy with acetone, it woked fine on the top cowl which i had previously coated with a straight mixture of resin,it took 3.5 hrs @95 deg. to be dry enough to sand.
. got brave and did the bottom with thinned 50-50 first time on. it took a lot longer to dry but sanded fine. second coat on the bottom took days to dry and seems uncured at times while sanding. it would sand fine wet but would roll when sanding dry. luickily it sands dusty dry today.
from now on i will just use straight resin spread with a new yellow bondo spreader. the brush streaks left by the brush were far more trouble to sand out than the streaks left by the spreader. spreader left two ridges the brush left multiple ridges and made sanding a dog.
my observation is that the acetone evaporates by about the third stroke and you have nearly pure resin any way. This makes me wonder if it is taking some of the hardener with it and increases the drying time. dunno
 
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If you are using West System - use a small radiator roller - it puts a thin coat on really well. Used it on all sorts of applications from rejuvenating fabric with dope, laying up deck cloth on a One Design, retouching 2 pack without all the spray problems.

Use the gloss roller for best results.
 
Clean First

Clean before doing anything. Use a high pressure nozzle, blow it out. Clean with acetone. Sand with rough paper, 80-100 grit. Clean again. Roll epoxy as described. No real need to thin. Don't use too much. Sand smooth. Done.

On the bottom, you might use some heat shield. Doing the above will dramatically assist in the adhesion of the heat shield.
 
mike newall said:
If you are using West System - use a small radiator roller - it puts a thin coat on really well. Used it on all sorts of applications from rejuvenating fabric with dope, laying up deck cloth on a One Design, retouching 2 pack without all the spray problems.

Use the gloss roller for best results.
Click to expand...

Mike, what's a "radiator roller" (got a photo). And can it be used to apply the epoxy straight (ie UNthinned).
 
The cowling of my -4 had been coated w/ epoxy which chipped and flaked w/ time and handling. What I would recommend for the lower cowl is to sand it smooth, thoroughly clean and apply Vans heat shielding to it. It will protect against heat damage, provide an impermeable surface to protect from oil staining....works great for me. And the top...you could paint it if you want but it will be fine w/o anything else.

Glenn Wilkinson
 
It's the small rollers you can get at Home Despot - about 4" long - like mini rollers for doing detail work Try either the foam one if using non volatile stuff like epoxy or the latex fluffy ones if using dope/solvent paint.

Use the epoxy unthinned but warm - lay out in a flat plate and play a hair dryer over it to thin it out - works well
 
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I've mentioned it before....you can buy an epoxy with the viscosity of water; System Three ClearCoat. Its intended use was soaking into wood for moisture sealing, which it does very well. It also soaks into exposed fiberglass.
 
RE:Where and how much???

DanH said:
I've mentioned it before....you can buy an epoxy with the viscosity of water; System Three ClearCoat. Its intended use was soaking into wood for moisture sealing, which it does very well. It also soaks into exposed fiberglass.
Click to expand...

Dan

Interesting stuff.....What is your source of product? How much product needed to do an RV7A.....?I did find some distributors on the net but would assumn you know the best at the best price. By the way any trick in using this product...?? other than roll or brush it one let cure and do it again?

Frank @ 1L8 ....RV7A... starting the prpe for paint......
 
Frank,
Last time I ordered direct from System Three. I've used a lot of it in wood wings.

As for fiberglass surfacing and pinholes, I've been experimenting and intend a report later. A brush coat would work fine on the inside of a cowl.

Dan
 
Sealing Fiberglass

I used Van's method...West Epoxy thinned 50/50 with acetone... on the exterior and interior. After cleaning the surface with acetone or lacquer thinner I sand the surface with a course grit (80-/+) disc in a orbital sander, apply the thinned epoxy with a auto body squeege working quickly and not worrying much about runs. I use papertowel, newspaper or rags to whip off any runs later and sanding will take them out if missed. It only takes a shot glass quantity of epoxy as it goes far and only mix a small batch as it cures fairly fast especially when the acetone starts to evaporate. I repeat the process one more time after another good sanding. After that I use finer grit sandpaper and give it a good coat of primer. This is followed by a close inspection for pinholes and I fill those remaining with spot putty. Blasting with compressed air after sanding will sometimes expose pinholes too. Sand and prime again followed by paint. I have finished the inside of the cowls to prevent oil from penetrating the underlying honeycomb. I don't know if this is the best method but I have done this a few times already and it does work and requires nothing that I don't already have on hand.

Dick DeCramer
RV6 N500DD 300 hrs. flying
RV4 N149KC flying
RV8 wings complete
Northfield, MN
 
System Three Clearcoat

System Three Clear Coat is also the epoxy of choice for clear-finished boats (such as strip canoes, kayaks, etc.) and works well for blister repair in fiberglass...flows right in and fills the blister. Good stuff.

Try Woodcraft for a small (12 oz) System Three Clear Coat kit; see:
http://www.woodcraft.com/family.aspx?familyid=4669

For a larger (3 qt) kit, try Boat Builder Central; see:
http://boatbuildercentral.com/proddetail.php?prod=S3_CLEARCOAT_3qt.

Good hunting,
Mike
 
I'm using Stewart System and was told to spray on the primer, which I totally love, until the surface is nice and smooth(with some sanding of course), than put on the top coat. Easy as pie, yum, I like lemon please.
 
Oil Saturated fiberglass

I've already got some oil saturation in a few spots of the lower cowl. I want to bond some ducting in this area. What do I do now?
 
Tough one Scott. If it is oil-saturated into the core material, I'd say remove the inner laminate, cut out the core, flush the backside of the outer laminate with a strong solvent, scrub with detergent and then fill the area with flox/epoxy and a glass fabric patch. Since you're planning to bond in ducting anyway, the solid core won't be a bad thing.
 
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