Do any of you guys use water based polyurethane to fiberglass and seal floats. If so how well does it work and is there anything special I have to do to make sure that water doesn't soak in? Also is a regular Interior/Exterior spray paint good for paiting floats, or do you need to put a coat of something over the paint before float flying. Sorry if these questions are sort of basic, but I'm in the process of converting my trainer to a float plane and I have no experience with float flying. Any comments or sugestions will be apreciated.
Thanks,

?What material are your floats? I use polyu. varnish for many applications on my planes. Recently I refurbed a 1/4 scale glider which had balsa skinned wings covered in white shrink film, this I stripped and applied l/wt glasscloth (10-17g per sqM) brushed on with wa.ter based poly. varnish, building up in thin coats until weave filled, rubbing down with 320 wet'ndry used wet leaving a hard flexible finish for any colour system. Ive also fixed boats in the same way! It works, its clean and its easy! The best in the UK is Ronseal Diamond, I'm sure any Home Depot in the US has similar.
Try it,
Daveosoar.

I have used water-based polyurethane varnish as a glassing resin. Doesn't stink, Doesn't eat foam, thin enough so that it can be brushed through light glass cloth, and it's a helluva lot less expensive than laminating epoxy. Cleans up with water-, but completely waterproof/fuelproof when dry.

I also like to build with polyurethane glue. Lighter than epoxy, just as strong, waterproof, fills joints as it cures. "Gorilla Glue" is a frequently seen trademark.

"Regular" interior/exterior spray paint is not fuel proof. It is fine for electrics, but glow fuel residue will melt it. You can buy fuel proof spray paint from most hobby shops and major on-line sellers.

Jim

What are some brand names of:

"water-based polyurethane varnish as a glassing resin" ??

I have no idea what that is.

N7OR, I use "Polycrylic" by Minwax. Like the others have said, it's water based so clean up is easy and it doesn't have a strong odor......Seaplane

All of the major poly varnish manufacturers have a water based version. Check with your local hardware/homecenter.

BTW; the oil based version is not fuel proof, but the water based version is.

Jim

Thanks for the info guys, I will use water based polyurithane to glass my foam/balsa sheeted floats. I bought a can of it and it is made by the Varithane company I hope it works. Now about the spray pant, would it be ok if I used a regular interior/exterior spray paint on my floats and then put on a coat of polyurethane on top? Or should I spend the money and get a fuel proof paint? Is spray painting really the way to go or is there a different painting method?
Thanks again,

LT-40

I used the water based Minwax Polycryl on my balsa sheeted foam core floats shown here. Rubbed on a very light coat with a rag so grain didn't raise too much. Laid on 1/2 oz glass to the dry surface and brushed on the poly with a cheap nylon brush ( natural bristles introduce bubbles). I quickened the drying time with a hair dryer. After two more coats I began filling the weave with the poly mixed with corn starch. Three coats of this, sanding between coats made the suface as smooth as a baby's butt. You must seal the cornstarch because some primers may cause it to pop or blister, so two more coats of plain poly to seal the cornstarch, fine sanding and they're ready for primer. I used automotive primer and auto base/clear coat for the blue and then Lustrekote orange to match my orange Monokote. This whole process is fast, could be done in a day with no problem. I have used epoxies for composite layups at work so I know how long the curing process is for that method, this waterbased poly is the way to go for models. I have a set of Goldberg Super Floats ready for the same treatment.

You might want to review the strings and posts that are at the following locations on this same discussion area:

http://www.rcuniverse.com/forum/m_4005831/tm.htm

http://www.rcuniverse.com/forum/m_4017125/tm.htm

What I mentioned about flying boats on one of those strings also applies to the waterproofing of floats. Monokote is a good waterproofing method as well, if the seams are well sealed. I have never had water get past a well sealed Monokote covering.

Damifino, thank you for sharing your method of fiber-glassing, sounds like a lot less time consuming than epoxy. It is probably a lot lighter too. I am about to start work on a Seawind and I am combing these boards for info on glassing, I've never worked with it before. Just got back from the paint store with a quart of water-base polyurethane, Varathane brand.

Very nice job on the Venture, it looks great on those floats, like a Schneider Cup racer. Very cool.

Best regards from old bird.

I can't take credit for the method. I got it from the instructions with my float kit from Niagra Custom Model Products. Sure worked good for me.

Water based polyurethane IS NOT FUEL PROOF! It is fuel RESISTANT, but quickly gets gummy after being exposed to exhaust. You can dust coats of Lusterkote clear to fuel proof, but one has to be careful. If it goes on too wet, it WILL attack the surface.

Only two-part epoxy paint is actually FUEL PROOF. Everything else is FUEL RESISTANT to some degree. Lusterkote, according to the Tower website, will not be damaged by raw fuel up to 15% nitro.

You are right though, waterbased Poly will get gummy if exposed directly to the hot exhaust. Using it on floats or seaplane hulls should not be a problem, particularly if you wipe off any raw fuel spills right away.

Jim

The top-coat being fuel proof is all that matters unless you plan on soaking fuel through from the inside out. Had no problem with the automotive primer attacking the poly and we put it on WET. My experience with Lustrekote gloss clear is that it gets gummy every time fuel gets on it. However, the Lustrekote colors seem to be very fuel resistant.

Same here. I used 3/4 oz fiberglass and MinWax Polycrylic (in leiu of epoxy) on my TF 182. Primer didn't bother a bit. I clearcoated some wheel pants with it once, and it the polycrylic was destroyed by 15% glow before I even landed. I clear coated a cowl on a gasser with it also. It has held up so far, but I can't say it's gas proof.

Minwax Polycrylic is NOT polyurethane and is NOT fuelproof. Even the name denotes "acrylic", not "urethane". It also is not as tough or hard as a polyurethane (either water or solvent based) and scuffs easily. I've used Polycrylic on a lot of kitchen and bath cabinets because I like the color the first coat gives to red oak, and I've tested it for fuel resistance and found it softens right up.

But there ARE waterbased polyurethanes that are tough and hold up very well to glow fuel. I made a universal engine test mount several years ago out of red oak and finished it with Flecto's waterbased Varathane. I've run many engines on that stand and have spilled a fair amount of glow fuel on it and it still looks like new. I also use Varathane on my shop shelving because it's almost as tough as a floor finish.

Again, Minwax Polycrylic is NOT polyurethane and is NOT fuelproof. There ARE waterbased polyurethanes that ARE fuelproof.

-Dave

With all due respect- The subject of this thread is a method to glass some floats. The water based clear stuff is very appropriate for the application. It does't stink, dries very fast, sands great and accepts primer and paint as good as anything. Please don't confuse the fuel resistant properties question with the original question in this thread. The top coat OVER the glassed surface is ALL that matters unless you are going to fill your floats with fuel. I will also used the method for glassing the foredeck on a bipe I'm building.