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Properties of early paints and varnishes

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Old 11-19-2007, 08:04:16 PM
bill chasser bill chasser is offline
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Default Re: Properties of early paints and varnishes


Thank you for your very informative posts. Having done a few restorations over the years with the old nitro cellulose lacquers and then with the acrylic lacquers and the acrylic enamels, I find myself now cursing the EPA wackos and their pursuit to now force yet another major industry change to water-based paints. I have never used the earlier type varnishes but was always in awe of the finished products that they covered. What a beautiful finish. I can certainly relate to the posts reply about hand rubbing the finishes to obtain the lustre. Very time consuming but that is what made a piece really stand out. To not only be an item of utilitarian purpose, but a work of functional art as well. Please continue your works into these finishes and share a lost art with all those who will most certainly appreciate your labors. I for one have learned a lot from every just listening to the wisdom of others.
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Old 11-19-2007, 09:00:45 PM
Patrick McNallen Patrick McNallen is offline
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Default Re: Properties of early paints and varnishes

You might want to google " Irish State Coach" and click on "Irish State Coach in UK Royal Mews 1 on Flickr Photo Sharing" on the first page of results for a color picture of one of the Queen's century-plus old coaches.
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Old 11-21-2007, 06:33:39 AM
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Post Re: Properties of early paints and varnishes

I thank you all for the excellent inputs.

I would like to catch up with my early promise to discus "japan black" first.
Then let's talk about linseed oil and lead fillers, to smooth iron castings;
talk about why leaded paints are restricted today,

and then get to the meat of the matter: that linseed oil as a binder/vehicle is the ideal for a smooth-brushing paint.


gilsonite, the resin and colorant of japan black, is used mostly in the asphalt industry. It is a premium form of asphalt, the oldest and most nearly fossilised asphalt in the world.

Gilsonite is most conveniently available in cutback form: dissolved in a residue-free solvent such as xylol. With the aid of heat the cocoa-brown powder of pulverized gilsonite (it looks exactly like Nestle Quik) will readily dissolve even in low-odor mineral spirits.

Solvents are rated on a scale of solvent power. Of all the standard hydrocarbon solvents, mineral spirits is the weakest of all. Although we can dissolve gilsonite in modern (weak, deodorized) mineral spirits, in less than two weeks time, the solution will polymerize and turn to a jelly. VMP naphtha is the next-strongest solvent; it is minimally-capable of keeping a cutback of gilsonite in permanent liquid form for long term storage.

However, to make a last-in-the-can forever solution, turpentine or old fashioned (no longer available) mineral spirits offers the minimum, reliable solvent power to keep the cutback in a fluid form.

Xylol is perhaps ideal for making a -cold dissolve- cutback. It requires a bit of time and stirring. Then we let the solution settled; dust and grit will fall harmlessly to the bottom of the container.

This solution can be painted straight onto clean metal, to which it will adhere pretty well--to rough castings.

Gilsonite cutback in (old, high power) mineral spirits made the "motor slush" that Ford used to quickly and cheaply paint the non-critical parts of the Model T: axels, frames, engines. The coating is jet black, moisture-proof, acid proof, alkali proof and offers a measure of rust protection (passive rust protection). It dries very quickly, and when fully dry, is flinty-hard and easy to sand.

Easy to sand: Such a coating was widely employed in the piano industry for smoothing the cast iron plates of pianos. One or more thick coats of gilsonite cutback, baked or air dried to full hardness, was then easy to wet or oil-sand to a level and smooth surface, after which a coat of bronzing paint would be hand-applied; and in earlier pianos, then overcoated with a high quality flowing (linseed oil/copal or kauri) resin varnish.

A beautiful result was thereby obtained. Bear in mind that gilsonite, being an asphalt, is always subject to re-dissolution by any hydrocarbon solvent stronger than, say, mere motor oil, unless it is fully topcoated by a solvent-resistant paint or varnish.

The neat things about gilsonite as a "paint" or varnish base:

-it is the blackest black of any black color ever made (so is any liquid asphalt, try it on modern black paint. While it is wet and glossy, it will show-out how far your modern black paint is from being a true black).

What is true black? Black is the absence of all color.
Black color is a surface that accepts and absorbs all wavelengths of visible light.
To be truly black, a surface must be perfectly glossy (wet-look); the slightest lack of gloss causes light scatter, and a perception of grayness will result.

All blacks other than asphaltic black rely on the fine-ground condition of high quality carbon particles.
Carbon derived from various sources tends to offer various casts: some are brown in cast (lampblack). Some are grayish.

The finer the pigment particle size, the blacker the black can appear to be.
Bright, full sun is the best light for adjudging black level.

The molecular-fineness of gilsonite's (or any asphalt's) carbon is why these materials offer the best standard for perfect black.

The funny thing about gilsonite: it is, when ground to powder, not black at all, but medium brown. And in solution, in thin film of less than a thousandth thick, it is amber and translucent. This is most evident in japan black.

Japan black is at basis gilsonite cutback in mixture with linseed oil and a small percentage of lead drier, baked to a permanent, insoluble cure.
In thin film (say on a piece of glass), first coat is honey-clear. Second coat is brown, fourth and fifth coats become nearly light-proof and offer that jet, glossy blackness only linseed oil and gilsonite can make.

Tung oil could be substituted for lineed oil in such a varnish (for this is a varnish now, not a paint), but tung oil will not dry to the perfect gloss of linseed oil.

What is the difference? Why is japan black truly a varnish and not a paint?

A: japan black is a varnish because a varnish is a drying oil plus a resin in chemical and physical combination. Gilsonite is a resin which happens to have a black color in thick-film form. Gilsonite is not a "pigment" per se;
a pigment is so-termed when a material is mechanically ground to a fineness suitable to the coating job at hand.

Gilsonite has no discrete particles to it; therefore it is not a pigment. It requires no grinding, therefore it is not a pigment. It absorbs all light entering its film-thickness, in the same way as does a dye-stuff.

Gilsonite, for japan black enamel work, is therefore a unique material.

But for filling rough cast iron: it may offer the engine restorer and easy, brushable, sandable, completely non-toxic alternative to the antique lead-based block fillers.

A simple gilsonite cutback solution, put on quickly (for it does not brush out well, for it has no oil to it) makes in instant, jet black, hard-dry, always-retouchable coating.

After it is fully hard, it can be maintained in high gloss by an occasional wipe with simple, pure mineral oil (which is of very low solvent power).

All mineral oils, however, eventually gum and attract dust, and therefore will dull.

OK, so now you have a simple means to make things, which won't be splashed with gas, or wiped down with mineral spirits, a permanent, rust-inhibiting, perfect black: the basic gilsonite "slush" coating. Dip, brush or spray. It will re-dissolve if hit with solvent. Over a period of years, it will dull down, even indoors, and go dead-flat, and gradually disappear from the surface.

To test for the presence of gilsonite on an old casting, such as an old, NOS Ford part, wipe the surface with a rag moistened in mineral spirits: despite the dull black of the coating, the rag will come away brown, not black.

What happens when we add a drying oil such as linseed? What is gained?
How is such a varnish made, applied and cured?

Next post: japan black; what it does and its general properties.
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Old 11-21-2007, 06:49:49 AM
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Default Re: Properties of early paints and varnishes

PS: this link to Zeigler today offers much more information about gilsonite than when I first read it there in the late '90s.

When and where you have a casting that you just want to -save- for a while longer from the elements, a quick and easy preservative is gilsonite cutback with store bought "boiled" linseed oil.

Linseed oil on its own was once considered an amazingly effective rust-inhibitor.
In the days when wrought iron fencings were common, it was said in one handbook on the topic of practical painting (1902), that straight linseed oil would stop rust and preserve from rust, any iron surface, better than anything.

That's not quite true, but on a practical level, it's true enough. Linseed oil absorbs great amounts of oxygen as it slowly and continuously cures, indefinitely,
and while it is in this state of flux (for years!) it will thereby scavage oxygen from the iron, and so prevent oxidation.

It was well-known by the mid-nineteenth century that even more effective rust-inhibition would be gained by making the surface "electro-negative", by adding to the oil red lead or iron oxide, etc. These made the first truly rust-proofing paints for exterior ironwork.

Gilsonite, per se, is not rust-proofing because it does not passivate the surface.
But, being acid, alkali and waterproof, it keeps such things from the metal, and so is a true metal preservative.

The cheapest and still easiest metal preservative is a simple cutback of asphalt in solvent, which can always be recoated (annually, preferably, because it attenuates in sunlight) without adhesion problems; no surface prep is needed.


So much stuff, but it's not really complicated to regain a working system, close-enough to the old ways, but still manageable and simple-enough for the modern beginner to master well-enough to gain useful practical results.
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Old 11-21-2007, 08:23:16 AM
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Default Re: Properties of early paints and varnishes

Originally Posted by Patrick McNallen View Post
You might want to google " Irish State Coach" ...
Time for a humor break.

Patrick, I live in Florida.
Marvel at the finish of the Florida State Coach

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Old 11-21-2007, 08:26:40 AM
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Default Re: Properties of early paints and varnishes

here's the other coach
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Old 11-21-2007, 11:59:10 AM
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Daniel Dorece Daniel Dorece is offline
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Default Re: Properties of early paints and varnishes

For several years now I have been using a 20/80 mixture of boiled linseed oil and turpentine as a paint base and rust preventative for iron castings. This works equally well on new cast or electro cleaned iron. Just make sure the iron is absolutely dry and allow a couple of weeks for drying time for the linseed oil. I have some castings that were coated several years ago and stored in an unheated area which look like they were cast yesterday.
Iron Wolf
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