Help! Waterproofing?

[Battery800]

So I’m building a seaplane, and I’m using maker foam. As a test, I put a little wingtip float in the sink and there were immediate leaks. Within a minute, all the paper cane off. If there a way to combat this? I’ve seen minwax, valspar, and boot sealant. Anyone tip in and give your thoughts/ experiences!

 

[The Hangar]

I've never used minwax on waterproof FB. Honestly most the time with a plane you're flying, so just being in the water a little bit when taking off and landing doesn't really matter for maker foam. Just an FYI the brown FTFB is a bit more water-proof than the maker foam.

 

[Battery800]

I've never used minwax on waterproof FB. Honestly most the time with a plane you're flying, so just being in the water a little bit when taking off and landing doesn't really matter for maker foam. Just an FYI the brown FTFB is a bit more water-proof than the maker foam.

My mess up trial hull shows that small dots of water get through, and eventually spread

 

[Ketchup]

Are you sure that you are using maker foam? The flite test stuff should already be waterproof. If it isn’t water proof for some reason then minwax might work. I haven’t personally used it but there is an old FT video on it. Also, hot glue won’t stick to minwax, so it has to be applied to a finished plane. Good luck!

 

[Piotrsko]

Worse case use thin cheap box sealing tape with overlap on the water touching parts.

 

[BATTLEAXE]

My mess up trial hull shows that small dots of water get through, and eventually spread

I have no experience with the Maker Foam myself but i know a good seal with HG at the seams and a coat of oil based poly, before paint as a primer coat, should seal things off. The FT vid shows also mixing polyurethane with baby powder to make a light slurry and apply that to build up almost a light shell of sorts. I think it was in conjunction with strips of brown wrapping paper like paper mache style. If that makes sense.

Here is the vid

 

[Battery800]

Are you sure that you are using maker foam? The flite test stuff should already be waterproof. If it isn’t water proof for some reason then minwax might work. I haven’t personally used it but there is an old FT video on it. Also, hot glue won’t stick to minwax, so it has to be applied to a finished plane. Good luck!

Yep it’s maker foam, with the box and everything. At this point, I think I’ll minwax then paint and valspar for an extra layer of paint protection and waterproofing

 

[Battery800]

Btw, what kind of paint do I use?

 

[The Hangar]

Btw, what kind of paint do I use?

Rustoleum X2 works really well. Just be sure to scuff up the surface of the foam before painting it. If you're coating the whole plane in minwax then it's not necessary.