Perhaps a little color theory is in order. I had to work with this in color television.

The human vision system integrates color viewed. For example, a very narrow bandwidth yellow combined with a very narrow bandwidth blue will be seen as green even though no green color is actually present. Two different green samples that appear perfectly matched to the eye may actually be composed of very different blue and yellow components that do not match each other.

The spectral response of many pigments resembles a cross section view of the Rocky Mountains. That's why two different pigments that may look identical to the eye may give very different results when mixed together.

Modern organic pigments may actually may have very different spectral responses than the heavy metal pigments they replaced. The spectral response may change as the pigment ages and fades. Problems with color matching and fading begin here.

Dennis,
Hence the reason we are stripping the entire car again, then using a thinned down oil based primer to soak into the poplar, followed by a thicker coat of primer, all rubbed down in between, followed by 2 coats of oil based gloss. The hail storm here in Cheyenne in May ripped paint off of most things, and naturally because we are outdoors and the hail came from a North West direction the car got hammered. The original primer coat had not penetrated the poplar very much so it means belt sanding the whole car now. If we could turn the car on its side and use a floor sander that would be better !

Mike Pannell

Cheyenne

Mike,

Is belt sanding the best way to remove the paint? I am just curious about how that would compare to using an architectural stripper. I have use belt sanders a lot, but they always seem problematic.

Is that procedure you are using for the new paint the same as you used prior to the hail storm?

For the soak-in trick the perfect material for that purpose is awlgrip 545 or equivalent 2-part epoxy.

Because after it penetrates, it cures in place and cures fully. It does not need air to cure.

One part products need air interaction to cure. Which is why they do not cure in the can.

The end effect is that epoxy primer acts a lot like Git Rot.

When priming it first coat I reduce 25% extra of course. I often watch for places where the wood has thirstily soaked it up, and i re-wet those areas. Several times as necessary. Even new wood can be thirsty like that.

As an epoxy it is both way compatible with epoxy body fillers such as Abbatron, git rot, West System, bondo etc. Anything can go on top of epoxy primer. Awlgrip 545 is compatible with most older surfaces, but the reducer T0031 hates latex paint. Which makes two of us!

The technical term used in paint matching is Metamerism:

http://en.wikipedia.org/wiki/Metamerism_%28color%29

It's the reason why paint colors are typically matched under three light sources... Tungsten, Florescent, and Daylight. That still doesn't account for differences in weathering... how many of us have touched up a Pullman green car, only to have the car slowly turn yellow, while the patches turned black?

Sorry to sound crabby about the paint, but I'm still pissed about the paint on my house. The point is, paint is more than color... it's the skin of the artifact, the first thing, no, the only thing that people see. There is no use in spending hours striping and lettering a car only to have it all fall off next year, and that is, unfortunately, a very real possibility.

The sorry fact is, the pinnacle of paint development occurred in this country in the 1940s and '50s... concurrent with the ultimate use of color on streamlined trains. Paints were formulated for the ultimate of durability, gloss retention, and colorfastness. Further strides have been made in some of those areas since, but always remember, the paint you buy today is formulated, first and foremost, to meet gov't regs. The question of suitability for purpose is in a distant second place.

So, we are faced with the task of understanding what paint really does, and finding the specialty products that best fulfill that criteria. Most of the stuff you can buy at the big box store isn't worth the money you pay for it. House paints look nice for 3-5 years. Automotive finishes are expected to look good for 5-7 years. Imron, if you can still use it, should be good for 30, but may not stay adhered to the substrate. Most of the coatings you can buy today are not designed to put a fine finish on wood, which is a living, breathing material that needs to be tamed before it can be painted.

I just hate to see time wasted on fancy decoration that isn't going to last.

Anyone who runs wood cars care to chime in with your preferred finishing products? Strasburg? Anyone else run a fleet of wood cars?

At WRM we use Awlgrip if we want a urthane. This paint system is designed for wooden boats. For an alkyd, Fine Pants of Europe is the best paint we can find for wood. Now that all of the cars at WRM are indoors, more Fine Paints of Europe paint is being used. It is about the same cost of as Awlgrip, but is easier and safer to use. Out of doors the FPE paint has about 1/3 the life of the Awlgrip paint. Awlgrip generally is used on passenger cars for a higher gloss and FPE is used on freight cars, as they have a good satin.

How'd you get a whole year???? I had a Rustoleum yellow turning to chalk within 6 months.


I disagree. I mean it's true that pigments have gone to hell in a handcart, at least certain colors which depended on heavy metals. (carbon black is doing fine, thank you.)

Resin, on the other hand, is worlds better than it was in the 50s. New resins are 2+ chemicals, both liquid, which chemically react to create a third completely different chemical - a solid. The components are toxic; the final product is nontoxic. The cured product is impervious to its own solvent! Since the resin components are liquids, the mixed-yet-uncured paint can do with less solvent, or even, no solvent at all (as is done in West System). Since solvent is VOC, that reduces the government issues with VOC's.

Spraying (as we know it) requires a fairly thin paint, and thus, more solvent. Awlgrip for instance can be mixed for either brush or spray; 1 gallon of Awlgrip base turns into 1.7 gallons when mixed and reduced for brush, and 2.3 gallons when mixed and reduced for spray. The difference is entirely solvent/VOC. The government regulates by market sector, and they brutalize automotive paint since so much of it is used, and there's no way to get body shops out of the smoggy cities. The result is a touchy product that requires a climate-controlled spray booth and very practiced painters. Amateurs applying it outdoors is not gonna work.


Imron is an excellent product, a 2-part "aromatic polyester polyurethane" using TDI. Two-part "aliphatic polyester polyurethanes" using HDI are slightly more durable and slightly less toxic. The hazard (isocyanate) is in the resin, not the solvent. When spraying, the hazard is huffing lungfuls of atomized resin. That risk goes away if you can roll/brush it. Several polyurethane vendors, notably in the boat market, designed their paint system to allow an alternate converter/reducer to be used for brush application.

Thus, small museums can get an Imron grade topcoat in outdoor conditions without serious personnel hazard. And that is why I do not share your pessimism toward modern paint.


Me too, given that the labor of prep usually falls to me :) I learned most of what I know under Dave Johnston.
What Dave didn't cover is that we use Awlgrip epoxy primers under pretty much everything, even if the topcoat will be alkyd. I have tried many types of topcoat over epoxy primer, and found no compatibility issues.

When working in wood, we roughly follow the Awlgrip playbook: We start with 545 epoxy primer reduced for penetration. If there is call for filler/fairing, we use any of { AwlFair , Abbatron, West System 407/410 } which are all epoxy products, so we can layer them with 545. A light coat of 545 gives an even surface to reveal defects, then more filler to suit. A final coat of 545, then topcoat of choice.

The only downside to epoxy primers is that sunlight destroys epoxy fairly quickly, so you can't stick it in primer for 3 years and expect it to be ready for topcoat. Other primers do that better, but are incompatible with 2-pack poly topcoats. For that, use epoxy primer as an "adapter".