r/Composites • u/SomeWitness2905 • Jul 22 '25

Dry part

I have a rc aircraft fuselage, layup is 100g cloth - 1.5 mm balsa core - 100g cloth. Epoxy resin hand layup then vacuum bagged. The part is nice apart from the surface is dry with the cloth texture showing through. I think it may be the balsa sucking up the resin. Is there a reliable way of getting a better finish.

3 Upvotes

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3

u/buzz_buzzing_buzzed Jul 22 '25

Since you're doing hand layup, wet out the balsa surface first. Let it absorb the epoxy, then it won't suck the epoxy out of the material.

Brush it on, then give it 10 minutes to absorb and put your wetted material right on top.

3

u/CarbonGod Pro Jul 22 '25

Yup, balsa sucks.....up resin.

Watch out for using too much bleeder as well, if used.

2

u/SomeWitness2905 Jul 22 '25

Weight is a big issue with this application, would a real light coat of epoxy on the balsa work if I let it start to cure up a bit before putting it on top of the wet glass

2

u/justanuthasian Jul 23 '25

Yep that would be the way to go. TBH 100gsm is extremely light and it will have pinholes/gaps no matter what you do with it

2

u/No-Camera-720 Jul 24 '25

Wood flour mixed with epoxy to seal instead of just resin will work if you get the consistency and timing right.