Fiberglass veil on boot, engine cover, doors

[Richard48Y]

Surprised to not see discussion of the "West System" epoxies.
Very popular with the Marcos guys.

[gideon]

Gavin, you could use peel ply to get a clean surface with unwaxed resin.  I got the idea from this discussion

https://forums.sailinganarchy.com/index.php?/topic/217776-peel-ply-unwaxed-polyester-resin/

I've had good experience with peel ply, so confirmation bias leads me to think this is a good idea.  A nice smooth peel ply would be best for paint prep - like this one

https://www.youtube.com/watch?v=raxYTCIkD54&t=104s

[gideon]

Richard, I'm all in favour of using epoxy resin but not everybody is convinced.  West System has a rather low heat deflection temperature (118F for 105/205 resin), so if buying laminating epoxy today I'd choose something with better temperature resistance.  There are lots of alternatives to choose from.

[RonPNW]

I found 2 cents in my pocket. (keep in mind, This will be the first time I paint a car)

Back in the day I did a lot of white water kayaking using fiberglass kayaks. The weekly repairs where aways epoxy based after some failures using polyester. The epoxy was stronger, more flexible, less prone to cracking, stuck better and could be easily repaired again without having to sand off a wax layer.

Fast forward a few decades and it seems the same properties still hold. I have many very old hidden epoxy repairs on my S2 body and none have cracked or delaminated. There are many exposed areas that now need repair and (for me) the most logical path seems to be internal structural repair (as much as possible)  with epoxy and fiberglass cloth (only enough resin to wet, squeegee off the excess). On the visible side, grind out the worst cracks and fill with chopped glass and epoxy. Veil on some areas of small cracks. Several layers of high build epoxy primer then paint. (of course lots of sanding and contouring at every stage.)

A key takeaway from my kayaking days was to use as little resin as possible and taper / adjust repairs to avoid making any area stiffer than any adjacent area. Abrupt changes in stiffness results in a crack.

Still looking for an easy way to fix cracks but grinding and refilling seems to be the only way. (OK, I heard someone say they had good luck with sanding off the paint and wicking super glue into the cracks. Could that work?)

Ron

[Clifton]

Epoxy has better mechanical bonding but if you use epoxy, you can't use polyester resin over it. It will not cure. Epoxy is a pain to sand too. Wet sanding is better.

[gideon]

Clifton, you can apply polyester over West System epoxy so long as the epoxy was mixed per the manufacturer's instructions, fully cured and then prepped correctly. 

https://www.epoxyworks.com/index.php/applying-polyester-gelcoat-over-epoxy/

I expect the same applies to similar epoxy resins but a cautious person would test first to be certain.

[GavinT]

It's not the veil that is a problem but a veil mat that prints through.

Thanks, Clifton.
Part of my confusion is that we're using the same name for different products.
The woven cloth in the lower part of your pic appears to be the really fine stuff commonly used by aero modellers? I'd say if that causes print-through, then any woven cloth will.

Surprised to not see discussion of the "West System" epoxies.

Hi Richard,
Nothing wrong with epoxies, I reckon, but I don't see any stand out advantage for what we're typically doing on a cost/benefit analysis.

Gavin, you could use peel ply to get a clean surface with unwaxed resin.  I got the idea from this discussion

Gideon,
I reckon there's some merit in the peel ply idea. I can see it'd help minimise creating pools of resin and also help control the layer thickness of the veil layup.
Have you tried peel ply with veil?
Also . . why the unwaxed resin?

Still looking for an easy way to fix cracks but grinding and refilling seems to be the only way. (OK, I heard someone say they had good luck with sanding off the paint and wicking super glue into the cracks. Could that work?)

Ron,
Kitty hair (fibreglass reinforced filler) - magic in a tin, I reckon.
There are long or short staple formulations available but I've only used the long.
If doing a large crazed/cracked area it's still easier to use CSM & resin but for many of the smaller ones, kitty hair is more efficient IMHO.

Never tried the super glue idea. It always struck me that you're still left with the potential for the crack to reform if the super glue hasn't entirely bonded to the both vertical sides of the crack.
I prefer to sand cracks out to a saucer shape and eliminate the vertical sides altogether.

[Clifton]

Clifton, you can apply polyester over West System epoxy so long as the epoxy was mixed per the manufacturer's instructions, fully cured and then prepped correctly. 

https://www.epoxyworks.com/index.php/applying-polyester-gelcoat-over-epoxy/

I expect the same applies to similar epoxy resins but a cautious person would test first to be certain.

Good to know on their's. I know gel coat is still polyester but I know 100% it is not the case with some though. I used US composite epoxy on my roof's spider cracks and then laid polyester resin over with mat, it would not cure. I called and they said you can't use poly on epoxy. West may be different though.

[Clifton]

It's not the veil that is a problem but a veil mat that prints through.

Thanks, Clifton.
Part of my confusion is that we're using the same name for different products.
The woven cloth in the lower part of your pic appears to be the really fine stuff commonly used by aero modellers? I'd say if that causes print-through, then any woven cloth will.

Surprised to not see discussion of the "West System" epoxies.

The woven, non random cloth can print through. My bottom two pics and your bottom left are what I am referring to. The random strand CSM like our cars are made of does not have the same problem but also does not have the same strength.

It is hard to see in my car but in the garage under the florescent light reflection it's noticeable if you are looking. Someone else wouldn't notice it but when you wet sand and polish then a month later see it, you know. I could give another wet sand but I'm ok with it. If I would have waited a month to cut/buff after paint it wouldn't have shown either.