[Boatanchors] Re: Wrinkle Paint

[Barry L. Ornitz]

Carl Huether, KM1H, wrote:

> I'm looking for a source of quarts or gallons in at least 
> black, gray, brown and blue.
> 
> Anyone have any leads? All my old sources are gone.
> 
> These paints were used on lots of stuff from restaurant 
> table bases to cars and our favorite boatanchors.
> 
> I don't want rattle cans.
> 
> How about making your own with the basic colors? I 
> understand its something to do with the thinner used?

No, not the thinner.  It is much more complicated than that.

Present sources are few and far between.  Motorcycle shops 
often carry cans of black wrinkle spray.  For colors, use 
several thin coats of colored lacquer over the black.  Make 
sure the black wrinkle has cured thoroughly before 
overspraying with the lacquer - waiting a week or two is a 
good idea. 

I believe Rustoleum may be making a wrinkle paint again.  I 
know they still make the Hammertone paints.  However the 
technology used today is quite different from that used years 
ago.  Modern wrinkle is based on a vinyl chemistry, and you 
are not likely to duplicate the many variations of wrinkle 
found years ago (wrinkle, crackle, crystal, hoarfrost, 
alligator, etc.).

Eastman's library had a several volume series on the history 
of paint and varnish technology.  One book discussed wrinkle 
finishes and had a lithograph showing about 20 commercial 
varieties.  I tried scanning the lithograph a number of times, 
but was never able to get a decent scan.  

The original wrinkle technology was based on tung oil with the 
proper drying catalyst.  Remember that oil-based paint does 
not really dry like a lacquer.  It reacts with oxygen in the 
air to polymerize and cross-link.  Carbon-carbon double bonds 
are needed in the oil (unsaturated oil) for the reactions to 
take place.  All oil-based paint cures from the outside in, 
which is why a skin forms first in "drying".  This is also why 
a thick drop of paint may still be liquid inside long after 
the surface of the drop has hardened.

With tung oil and the proper catalyst, as the polymerization 
occurs, the material expands.  This is what creates the 
wrinkles, as there is no place for the surface to go but form 
wrinkles.  The use of other oils and catalysts similarly 
produced a paint that shrinks as it cures.  This resulted in 
the "alligator" surface.  By changing the drying conditions, 
and the paint composition itself, it was possible to create a 
number of different finishes.  One common technique was to use 
a gas-fired drying oven run rich so there would be carbon 
monoxide in the combustion products.  This also reacted with 
the paint to affect the surface finish.  The paint industry 
used the term "gas checking" to describe the process.

While we might consider the wrinkle paints to be high class, 
they were exactly the opposite at the time they were commonly 
used.  They were developed to be a cheap paint that could 
cover in one coat.  They did not require an exceptionally 
smooth surface underneath, and they did not show the lack of 
skill of the painter that high gloss paints would.

Many modern paints will wrinkle if applied very thick and 
force-dried with heat lamps.  However, the results are not 
nearly as reproducible as the old paints.

Hammertone paints, however, are simple by contrast.  These are 
nothing more than thin paints containing aluminum and 
sometimes mica powder.  A "hammered" effect can be obtained by 
using a paint gun adjusted to splatter droplets.  With some 
practice, most people can get a reasonable hammered finish by 
using a stiff brush, like a toothbrush, to splatter solvent on 
partially dried metallic paints.

Today, the method of choice to produce textured finishes is 
powder coating.  Here an electrostatic spraying process coats 
the item to be painted with a powder.  This is then passed 
into a heating oven to melt and polymerize the powder.  
Eastman sold off this part of their business before I ever had 
a chance to learn much about the technology.

          73, Dr. Barry L. Ornitz     WA4VZQ     ornitz@tricon.net