Water Based Paint v. Acrylic or Urethane

[remotemark]

One of these days, I hope, my ne-er do well body shop guy is going to get around to painting my coupe. He's given me a choice of using the newer Glasurit water based paint if I want it. He says MB has been using water based paint for 12 or 15 years now and that the tint is more durable than the older acrylic and urethane paints. Does anybody know if I should be going with the water based?

[TX76513]

That's true they might have even pioneered it. Glasurit has a very short flash-off and dwell time make sure your guy has knowledge of its characteristics

[Mike D]

If he'll do it with the BASF Glasurit 90 waterbourne series of paints then go for it. You'll get a much better color and durable paint than the original. Added bonus is it is also better for the enviroment.

Starting in July of this year, waterbourne paint will be your ONLY choice of respray in Californio.

It's a little different to spray I've heard but I'm looking forward to working with it when I respray my '74 280C "anthracite gray- clearcoat"

I'm used to working with Imron urethanes and I can't wait to get away from THAT nasty stuff.

[remotemark]

Well, now that I told him I'd like the 90 line, he is trying to get me to pay part of the cost of some new machine he needs to use it. He apparently has used water-borne paint at some other shop, but isn't set up for it at his shop yet. He claims the machine is $2500.

I think I'm going to have to sue this guy to get my car back. He's had it for four months now. He does really nice work, but it's now clear to me that he treats non-collision work like a hobby.

[Dee8go]

Is the Glasurit any less hazardous than other paints, also?

[Pete Geither]

We are not using water base yet, but understand it is coming,,, I hope to be a former business owner when the big change comes, but I digress. The water based base coat is the only thing that really changes in the process. In using water for a reducer, instead of petroleum reducers, VOC's are almost eliminated, in that part of the process. The same clears, which are really quite hazardous, are still used. I understand you need some way to really circulate the air, that even our downdraft booths won't do in a timely manner. So it means getting a new style downdraft, or investing in expensive air circulation devices to speed the flash time.

[Dee8go]

"It's not easy being green . . . "

Kermit the Frog

[jmk]

Well, I better get involved with this one.

I don't think that you will find the waterborne to be better (except to your health) than solventborne coatings, but you can do a good job with them.

Rule 1: Don't spray it w/o adding the isocyanate. You will find that it will dry w/o the hardener, and a lot shops cheat, but it will not be durable.

Rule 2: Face/flop matching is harder, coatings tend to be more "grey". This one is hard to explain w/o jargon, but latex particles are quite large compared to solution resins so getting a deep flop and bright face will be harder. If you are familair with the difference in application between high solids and low solids paint, waterborne will be like another step away from low solids application. Practice your application until you get used to the differences. Metal control will also be harder.

Rule 3: If you have electrostatic applications, they probably will not work with waterborne. You will need to buy a system designed for waterborne that doesn't charge the paint until it leaves the gun. Conventional electrostatic applications will "leak" or short out the gun. In OEM, there are waterborne compatible electrostatic combinations. I don't know the state of the refinish equipment at this time.

Rule 4: Waterborne dries fast. It is harder to touch up.

Rule 5: I doubt waterborne is more durable yet. I have never found a properly designed solventborne to be less durable to an equivalent quality waterborne. The two are closing in on each other. Solventborne durabilty is decreasing mainly because the Mw, or size, of the resins is getting smaller in solventborne to be able to spray while using less solvent. The smaller a polymer is, the less solvent you need to bring it to spray viscosity. Waterborne has film forming issues. The latex particles are large (from 100,000 to 1,000,000+ Mw), which helps durability from a size sandpoint. Unfortuately, the particles tend to not knit together on the molecular level because they are so large. Think of solventborne as being like concrete and waterborne being like a gravel road. Also, there are surfactants used to disperse the resins in water. The surfactants always add a degree of water sensitivity. There are many ways of improving latex, but they are not quite up to the best solventborne yet.

I do know of some interesting technology in development that will help with the VOC issue and with waterborne performance issue, but I can't discuss it at this time. When I can, I'll talk about it.

One thing on the safety of waterborne basecoats: they are significantly safer for the environment, but won't necessarily be significantly safer for the painter. First thing, there are coalescing solvents in waterborne. Some waterborne formuations can have more solvent than some high solids solventborne materials. Waterborne coatings usually have less solvent that solventborne these days, but do not think that there are not any solvents in waterborne coatings--even if you cannot smell them. Secondly, isocyanate is still dangerous. Placing it in water does not make it safe.

Also, do not compare the factory waterborne to the refinish waterborne. They are as different as the factory and refinish solventborne. They are very different beasts.

It is true about the clears. They are the same solventborne material. The industry is not yet ready for waterborne clear. VW tried it a couple of years ago in an OEM plant. It did not work out well. The physical chemistry of creating a waterborne clear is quite daunting.