I went to a PPG sponsored seminar on water based paints.....

They sound way cool, being thinner for full coverage, and I was surprised that all European cars are painted with water based paints for the past decade....It's coming!

I have asked for a synopsis of the talk, and expect it soon. I'll publish details.

This is a great environmental move. However what happens to wood when you get it wet with water?

As a mechanic I can say this, If its California Legal,Bio degradable and non toxic. It does not work!

A local guy, Mike Haverly, has used Auto Air Colors (a water based urethane) on his las couple of planes. He says it works pretty well. I've only used it for some trim colors, but they worked well. Auto Air Colors is still working on a durable, water based clear coat, but the stuff seems to do well with most any conventional topcoat. Nice thing about it is, it's largely non-reactive to other paints, so it's pretty easy to build up a substrate with dope, then use Auto Air Colors for all the colors then use either a dope or catalyzed polyurethane for a topcoat. To top it off, the stuff is pretty cheap and covers very well.

Spark....you're probably against them because they represent change....you more than likely got mad that the Motor Company quit with kick starters, too.
The PPG guy felt that there ere many advantages and few drawbacks.......he also said that tap water is a no-no.....stressed that de-ionized was okay, but that some "water" PPG sells is best as thinner....solid colors only need 10% thinning, while candys and pearls need 20%.....
He also said that the clean-up was tougher, because it's hard to get the latex from the nooks and crannies.....
Two part solvent based clears are used in all commercial applications, BTW.

 Tom,

 Thank you. After the picture was taken (Breitenbach contest 2007 in Switzerland) I have had the wings replaced. They are all-white at the moment, maybe I paint something during the winter. L

 I don't know about Buicks but Yatsenko's planes are mainly made of wood. Fuselage skin is 1,5mm balsa, it thins down to 0.8 towards tail. Flaps, stab and tail skins are from 0.7-0.8 balsa. The wood is covered with 17g/m2 glass cloth, 2 layers on outside and 1..2 layers in inside. In wing skins they use Herex foam (1,3mm) exept for the Yak and my planes that come with balsa skin with glass on both sides. Balsa skin is lighter and stiffer than Herex skin.
 They don't use gelcoat, paint after molding is lighter. It's very naive to think that they just pop out of the mold ready to go.
 The point with the water colours is that once the surface is sealed, wether with paper/dope or glassfiber/epoxy, they work well. Of course it's not possible to use water based products directly on the raw wood. L
 
 

In my professional experience as an automotive painter, the water based paints have been around a while, and they do work, if you follow the guidlines. Robert as far as getting water based finish on the wood, that isnt an issue even with a conventional stuunter, you stil have to seal the wood and open bays before you finish, so a substrate is needed. whether it be dopw or other material, the color coats are what is waterbased, and it by neccessity sits on top of the base materails. I dont know of anyone that puts color coats on bare wood?
These materials that are designed to be enviromentally freindly are typically implemented in california because they are the most fnicky, and yes initially, some of the products have issues to begin with. Do you recall all the cars in the early 90s that had issues with the color coats pealing, yeah well that was a result of not enough UV protection in the clearcoats,, a problem that began with regulation by the EPA and a deadline that was not realistic. But they did sort it out, and Urethanes we have today are the result. Progress has a price, just like with computers,, to be on the leading edge has a price.

The guy from PPG mentined that about twice the air flow is necessary.....most ar using hand held vortex generators powered by shop air...
Modeling use wants a hot rod heat gun....
He reported that it was dry to mask in three to five minutes....

Arch,

Well, if you are finishing fiberglass or other closed structure surfaces, then it's possible to use a non-lacquer finish entirely and probably possible to go from the wood up with non-toxic stuff, though you'd probably still need some sort of epoxy or at least toxic chemical based material on the bare wood. I tired a water based urethane on bare wood once. Interesting outcome. I wouldn't do it again.

But if you are using an open structure, you are still stuck with some sort of lacquer for at least part of the finish. I gave a try to using a urethane based clear on bare wood and open bay silkspan once. I sort of got it to work eventually using a heat gun when it was wet, but the shrink, such as it was, was uneven and caused warps that I spent a lot of time chasing. Mark Scarborough and I have discussed all sorts of alternatives to using lacquer with open structure planes. It's possible with stuff like polyspan or thermalspan. but it introduces other problems. We wanted to come up with an all urethane finish method.

The experiment goes on.

Nelson water based system is designed to be applied over nitrate dope-based substrate. Their paint is nitrate resitant to 10% nitro. For higher nitrate content, they sell something called "cross-linker" which makes it resistant to something like 50% nitro. Any filtered water will work as a thinner. Another cool benefit is that one can apply another coat as soon as applied coat is dry. That could be as quickly as 5 minutes if being "prodded along" with a hair drier. That's right! It can be dried with a hairdryer with zero affect on the adhesion or pigmentation.

My next world-beater is getting a nelson paint system! I was going to use it on my 35 Stilletto but had one of those idiot moments when I applied a coat of buterate dope mixed with Zinc Stearate I had left over from the last model.

Have to admit that I don't have any experience with water based paint other than Auto Air Colors. But I like the stuff. I will use some for trim on my new plane.

Hi Mark....
PPG guy says that it's essentially like house paint...
The effluent cannot be swept up, then hosed down a drain in California, but, if allowed to dry, the solids are disposable in a landfill....
Too much of almost anything is harmful.....lol

*** if allowed to dry, the solids are disposable in a landfill....***
The same exact fact is true about  catalysed Urethanes as well. the cured dry material is considered inert and needs no special disposal techniques. You all can treat it as you want, but for me, its the same same as all other materials sprayed, full on respirator, and good supply of fresh air. In fact you will likely still see me wear my shoot suit were I to be seen spraying this stuff.

I've tried Nelson's clear over silk and dope as a fuel proof topcoat on a Free Flight that will see 20-30% Nitro. It was applied with a foam brush and I'm pretty impressed with the result. I did notice that it will sag and run very easily, but I'm sure with some experience I will be able to put it on well. As a matter of fact, I think my next stunter will be all Nelson's, color and all.