rsieminski

What can I use to seal the foam? I'd like to use polyester resin.

downed corsair

the polyester resin will eat the foam you should use an epoxy resin heres a good website for it www.fiberglast.com

james

rsieminski

Yes I know the polyester resin will eat the foam, that's why I want to seal the foam before I apply it. For epoxy, I prefer the one here:
http://www.fgci.com/cgi-bin/dpsmart/...01type_0205_01
It is easy to use, less expensive, can be heat cured, just a great product. But, on this project, a ton of it is needed, so the less expensive polyester resin, would be a better choice. But, I need to seal the foam.

downed corsair

oh sorry bout that i thought you meant you want to use polyester resin to seal the foam what are you building can you sheet the wing with balsa or are you lookin to kee; the weight down
sorry
james

rcalfred

In Forbes Aird's book Fiberglass & Composite Materials he says "There is a material that is cheap, generally available, and effective for this purpose. The secret is ordinary exterior latex house paint. It must say "alkyd" somewhere on the label--interior latex paint is unsuitable. And the paint must be sprayed.....it is a bit thick for spraying so thinning with a little water may be necessary." As with anything...always experiment on something other that your finished plug. Regards.

rsieminski

I'm making an airboat for the kids...and me. The 4y/o is a little too young to begin flying, but he understands the boats. I've messed up 2 plugs so far: Epoxy kicked too soon(the last I had), and thinned Bondo never dried. I've only done small projects, like gear and wheel pants, etc. This is a bigger project, and thought I'd save a little and use Polyester Resin.

Terryoc

If you are going to leave the foam on the inside you can use polyurathane expanded foam ,this is used in ice chests and I think surf boards as it is not attacked by polyester .
BUT DO NOT HOT WIRE CUT IT AS IT GIVES OFF CYANYDE FUMES.
Hope this helps
Terry

Darrinc

My Feedback: (5)

Polyester resin is not a structural resin and will never be, put enough on and it will fix your bass boat, but it's worthless in our field. You can buy epoxy with a hundred different hardners to get what ever pot life you need. It's the real deal.

rsieminski

I'm making a boat. But the question was how to seal the foam, not epoxy -vs- poly. Poly can be used as a "structural" laminating resin in many applications, as can epoxy. Some situations would be better suited to epoxy, and some you can save some money, because poly will do just fine.

canadianjosh

i ran into the exact same problem when building my airboat, except, there is a foam out there resistent to polyester resin, it is light yellow/tan in color i think it is called closed cell extruded polyethylene or something like that. I got it from a place called Industrial Paints and Plastics. Phone a shop that sells foams, fiberglasses, rubber, lexan, plexiglass, that sort of stuff and they should be able to help you out, a 2foot by 4 foot piece of this cost me 19 cdn$. This stuff is really good too because since it is closed cell it will not absorb exces resin, or water in the case of a puncture or delamination. My airboat is almost done i'll have pics up soon. Also, i have used one layer of 4 oz on the top, one layer of 4 oz on the bottom, and the hull is as stiff as can be, ppl are misled by the whole epoxy vs poly bit, it's simple, when epoxy cost 3 times as much, and you can acheive a good stiffness with poly, go for the poly.

goony

Cover the foam in PRO film or similar give it a squirt of house hold polish and away you go BUT dont leave any gaps also where the pro film overlaps it will leave a thin line but this is easy to rub out

regards goony

rsieminski

Josh,
Ya gotta send me some pics when it's done, and I'll do the same. What are the dims? What size engine? Single or dual rudder? Motor mount? You can email me. Thanks!

goony,
What's PRO film?

goony

ITS the shiny plasticy stuff you cover youre models in
in england pro film is a trade name you probably call it something else if you use the sticky back stuff then no heat is required

goony

TGoodwin

I usualy spray on a coat of water based polyurathane then cover with glass and epoxy resin. Then shoot with FeatherFill polyester primer/surfacer. The polyester fumes will eat cavities into the foam if you have any pinholes in the glass/epoxy but not if sealed with polyurithane.

Just my $.02

Ted