Cowl with zits

[wirejock]

Ever seen a cowl go through puberty and get some serious acne zits? Click on the photo and zoom.
Go ahead and laugh. I did.
Long day of work gone. Oh bother. At least it's easy to find all the pinholes. Apparently the air in the pin holes off gassed. Curing room must have been too warm.

[Kyle Boatright]

Ya gotta push hard with your credit card/squeegie or whatever to push the material into the holes and push the air out.

[wirejock]

Originally Posted by Kyle Boatright

Ya gotta push hard with your credit card/squeegie or whatever to push the material into the holes and push the air out.

I thought I did. Clearly I need an industrial size squeegee! Round two after this mess gets sanded off!

[Kyle Boatright]

Originally Posted by wirejock

I thought I did. Clearly I need an industrial size squeegee! Round two after this mess gets sanded off!

What are you using? Some folks recommended sheetrock mud, but that didn't work very well for me <I still had a bunch of pinholes>. I went back to an epoxy wipe.

[David Paule]

One thing that might help is heating the shop, letting the cowl soak in the heat, shutting the heat off and doing the epoxy. As the shop cools it tends to draw the epoxy in to the pinholes.

Haven't tried this with my cowl, but it definitely works with wood parts (on a previous project).

Dave

[emsvitil]

They work like the dimples on golf balls and cut down the air resistance.....

[wirejock]

Originally Posted by Kyle Boatright

What are you using? Some folks recommended sheetrock mud, but that didn't work very well for me <I still had a bunch of pinholes>. I went back to an epoxy wipe.

Same as every other part I've done.
Skim with neat epoxy.
Cure 30
Skim with neat epoxy
Cure 30
Skim with micro.
I probably wasn't forcing the epoxy into the holes. Should be easy to find them after sanding.

[BillL]

Are you using a steel squeegee? It can apply more pressure on the edge, and leave a thinner layer to sand.

But thinking, I don't think it is the root cause. I recall seeing some acrylic tables (or maybe it was a cooking show) being poured and they took a torch and waved over the top to bring out the air bubbles. I wonder if a heat gun could do that on an intermediate pass (well before the epoxy has begun curing) to identify any voids remaining. Just a wild thought.

Also, my painters just sanded all my glass down to the weave anyway.

[AdamB]

You're not the first to be working on the project for so long it's reached puberty..

[BJohnson]

Are you using an elevated temperature cure? Fiberglass skins over core are notoriously porous, not just on the surface, but though the thickness too. It looks like you used a heated cure and air is being forced out of the core cells, bubbling up the epoxy and micro.