Question about glassing with WBPU... please help. - RC Groups
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Jul 25, 2002, 09:15 AM
Registered User

Question about glassing with WBPU... please help.

I put some glass cloth with WBPU on my project yesterday.
From what I've read and seen here, I thought the result would have been much more shiny/stronger than what I have...

I thought it would become as hard as plastic, or glass ! The foam is not realy harder than it was before the glass cloth was applied. What could explain that ? Not enough WBPU ?

I'm covering pink foam, using .75oz cloth with BEHR Water Based Polyurethan (High gloss).

Please if anyone can give me some advice, it would be very appreciated.

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Jul 25, 2002, 09:30 AM
RPV builder & operator
Pierre Audette's Avatar
I think part of the problem is that the foam may absorb some of the WBPU, so you're not getting a silky smooth hard finish, but that's fine. You just want the glass to bond to the foam. I usually put on 2 or 3 coats of WBPU, to try to fill the weave as much as possible, w/o too many pin holes. It's not going to be puncture proof, or heavy ding proof, but it's does stiffen up the foam significantly and enough for flying. I seem to be getting a much harder and tougher finish on balsa than foam. It also takes some time for the WBPU to dry completely and harden.
Jul 25, 2002, 09:34 AM
Registered User
I see... It's gonna be 24h since the first coat this afternoon, I will try and put a second one... As you said, I think it might have been absorbed by the foam.

Hey I see that you're in Hull... I'm traveling to Hull and Ottawa once a week for work, can you recommend a few good Hobby Shops in that area where they hold Electric stuff ?

Thanks for your help by the way !

Jul 25, 2002, 11:20 AM
Registered User
Pierre, have you ever weighed the plane before and after you've applied the WBPU? I'm wondering how much weight it adds. Does the foam absorb more than the balsa?