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Using Asphalt as a coloring agent - the facts


Joe Leahy
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I'm curious, who here has actually used asphalt?

post-3950-0-67288400-1292097909_thumb.jpg

I imagine that modern refinery asphalt may well be worlds away from the various Rennasance era naturally occuring asphalt products.

Asphalt is tempting because makes a very nice violin colorant.

This violin (circa 2005-6), using DMO (Darnton Mastic Oil) varnish over orange shellac uses dissolved asphalt in turpentine as an oil varnish colorant. We'll see how well it does over time...

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I can't get my head around why you would want to try when the Italians never used it, never experienced darkening and there are inorganic alternatives available anyway.

Because the alternatives I have seen for brown colorants are not transparent.

So far, I see no hard evidence for Gilsonite causing varnish to darken or fail, or even asphalt. Just "worries" based on possible problems. The only hard evidence I've see so far is for non-failure... those who have definitely used it have had no problems, thus far.

Some other evidence for non-failure, if you trust stuff from Wikipedia:

Ford used two formulations of japan black, F-101 and F-102 (renamed to M-101 and M-102 after March 15 1922). F-101, the "First Coat Black Elastic Japan", was used as the basic coat applied directly to the metal, while F-102, "Finish Coat Elastic Black Japan", was applied over the first layer. Their compositions were similar: 25-35% asphalt and 10% linseed oil with lead and iron based dryers, dissolved in 55% thinners (mineral spirits, turpentine substitute or naphtha). The F-101 also had 1-3% of carbon black added as a pigment. The asphalt used in the Ford formulations was specified to be Gilsonite; this has long been used in formulations of paint for use on ironware[3] as it increases the elasticity of the paint layer, allowing it to adhere to a steel surface subjected to vibration, deformation and most importantly thermal expansion, without cracking or peeling. It is also cheap, yields a glossy dark surface, and acts as a curing agent for the oil.

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Some other evidence for non-failure, if you trust stuff from Wikipedia: ...

Don, I don't know if that stuff held up well or not. I think it was some people at the Henry Ford Museum who told me that it was used for a period of time, and then they switched to a soy oil based enamel (around 1930?). It would be interesting to see a car which hadn't spent much time outside, with the original paint.

I guess asphalt-based products were used as interior surface rust preventive coatings and sound deadeners (undercoatings) long after that though.

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We do seem to have a few conflicting assertions here. Some say asphalt color fades in the light. One says it gets darker. I can only say I have never seen a tar roof or road get blacker over time. They usually don't turn white rapidly, either. I have also seen no difference in the drying of linseed oil when I have used asphalt in varnish. I don't use a lot and it is never my only coloring.

CT: If I recall, my asphalt is "type 4," or something like that. It was sent to me by a friend who was then in the roofing business in Arizona. Very hard and brittle. Sound familiar?

Lyle

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It would be interesting to see a car which hadn't spent much time outside, with the original paint.

Not a whole car, but a model T lantern claimed to have the original paint can be seen here. Doesn't look too bad to me. I've seen linseed oil varnishes that looked really bad, yet we don't seem to be avoiding that stuff.

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We do seem to have a few conflicting assertions here. Some say asphalt color fades in the light. One says it gets darker. I can only say I have never seen a tar roof or road get blacker over time.

I never got in to thorough testing, because of the Weisshaar warning. He approved some things which looked bad to me, so if he condemned other things, my short-term conclusion was that they must be extra-bad. :lol:

The perception of color can have many different components. Black paint can appear white, under the right lighting or surface conditions.

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Not a whole car, but a model T lantern claimed to have the original paint can be seen here. Doesn't look too bad to me. I've seen linseed oil varnishes that looked really bad, yet we don't seem to be avoiding that stuff.

Fair enough. There are plenty of varnish nightmares having no connection with asphalt.

Question: How do we know if asphalt/linseed black paint has gone blacker with time?

To be clear though, I don't really know more about the stuff than most other people, and don't mean to come down solidly on one side or the other. I got some from the La Brea tar pits when I lived in Los Angeles, fooled around with it a bit, and had moved on to other things by the time I started doing accelerated aging tests. The Henry Ford Museum might still be a good resource. I'd try to help out with this, but I don't know the people at the museum any more. The staff changed, and the new staff and I had some fallings out relating to the fiddles there.

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Okay, it's have a laugh at the new guy time. I've been learning a bit (but not enough) about mixing colorants in varnish, and it is used by one of the makers on here whose varnish I really like, so I decided to try it. I already had put several coats of Hammerl red-brown varnish on a violin with a gelatin ground and Hammerl red-brown water stain, but I wanted it darker. I mixed some Kremer bitumen (asphaltum) in some pure gum spirits of turpentine, shook it up, then thinned my red-brown varnish with it and proceeded to varnish the instrument.

You can imagine what kind of gritty texture that gave to that coat of varnish on the instrument. Little black dots all over it... :) Then I learned that you are supposed to let the bitumen dissolve in the turpentine several weeks and filter out the grit before using it in varnish - oops!

So I broke out the old 0000 steel wool and cut that coat off the violin and got the instrument back smooth again, and started using Hammerl dark brown tint to darken the red-brown varnish. There were two lessons that I decided to learn from this experience:

1. If you don't know anything about what you are doing, don't do it.

2. Become very familiar with, or even master, one manufacturers product line, before adding stuff to it.

It seems that the more I try to make myself a violin with the tone I want, the more I learn what not to do the hard way... :)

Bill

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Okay, it's have a laugh at the new guy time. I've been learning a bit (but not enough) about mixing colorants in varnish, and it is used by one of the makers on here whose varnish I really like, so I decided to try it. I already had put several coats of Hammerl red-brown varnish on a violin with a gelatin ground and Hammerl red-brown water stain, but I wanted it darker. I mixed some Kremer bitumen (asphaltum) in some pure gum spirits of turpentine, shook it up, then thinned my red-brown varnish with it and proceeded to varnish the instrument.

You can imagine what kind of gritty texture that gave to that coat of varnish on the instrument. Little black dots all over it... :) Then I learned that you are supposed to let the bitumen dissolve in the turpentine several weeks and filter out the grit before using it in varnish - oops!

So I broke out the old 0000 steel wool and cut that coat off the violin and got the instrument back smooth again, and started using Hammerl dark brown tint to darken the red-brown varnish. There were two lessons that I decided to learn from this experience:

1. If you don't know anything about what you are doing, don't do it.

2. Become very familiar with, or even master, one manufacturers product line, before adding stuff to it.

It seems that the more I try to make myself a violin with the tone I want, the more I learn what not to do the hard way... :)

Bill

Bill,

Part of the irony here is that the use of bituminous asphaltum was a purely German tradition but very few people are interested in studying German violins or Germanic violin making practices.

I thought this would change as the price of Italian violins went through the roof and so alternative sources of decent instruments would be explored. But this has not happened. With the exception of one expert, you will not find a violin dealer in America who could identify any German or Austrian violin maker. They could tell you the violin is German or Austrian but that's as far as it goes because there is no financial incentive to study any violin traditions apart from Italian/French.

Basically, Germanic violins are considered second rate. So I'm at a loss to understand the fascination with their coloring techniques.

Glenn

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Bill,

Part of the irony here is that the use of bituminous asphaltum was a purely German tradition but very few people are interested in studying German violins or Germanic violin making practices.

I thought this would change as the price of Italian violins went through the roof and so alternative sources of decent instruments would be explored. But this has not happened. With the exception of one expert, you will not find a violin dealer in America who could identify any German or Austrian violin maker. They could tell you the violin is German or Austrian but that's as far as it goes because there is no financial incentive to study any violin traditions apart from Italian/French.

Basically, Germanic violins are considered second rate. So I'm at a loss to understand the fascination with their coloring techniques.

Glenn

Glenn,

I did not know that the use of asphaltum was a Germanic tradition, nor was it my intention to study germanic varnishing... what I have been studying, or at least trying to study, is a modern-day Brazilian technique that produces some of the most beautiful red-brown viola varnish that I have ever seen on the Internet. :)

Imitation is the most sincere form of flattery.

Bill

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Glenn,

I did not know that the use of asphaltum was a Germanic tradition, nor was it my intention to study germanic varnishing... what I have been studying, or at least trying to study, is a modern-day Brazilian technique that produces some of the most beautiful red-brown viola varnish that I have ever seen on the Internet. :)

Imitation is the most sincere form of flattery.

Bill

Oh, That's easy. You're talking about Luis's instruments... He's posted his techniques on many discussions. :)

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... and test on scraps of wood first.

Thanks for jogging my memory Don..........I remembered a box of samples from the time I was playing with "blacks". The Asphaltum sample: gilsonite dissolved in turpentine and the [over] loaded into a simple rosin/oil varnish, then polished. The sample is over ten years old. It is a decent brown if you ignore how opaque it is [more opaque than I remember]. No surface degradation. Those samples sat in a sunny window for a year or so before I hid them in a box. Now they will enjoy a new, albeit brief, life as kindling...

My camera battery is down, but I'll take a picture of this before it heads for the wood stove.

on we go,

Joe

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Maybe this is naive, but I thought asphalt/bitumen/pitch were more less used in art and varnish as a substitute for Mummy.

All of these then would more or less be valued for adding well disolved and decayed dead stuf. In this light, the 'best' asphalts/bitumen/pitch sources for art work would be natural and tending to the less refined and less clean.

I would imagine such materials would vary a great deal in their actual composition.

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I would imagine such materials would vary a great deal in their actual composition.

I believe you are correct.

In particular, modern refinery asphalt - when lumped in with the rest - would bear little resemblence to a naturally occuring material, thus, would inevitably also display different properties.

"The facts" about some of these very different materials, (both modern and ancient or natural) without confusing them as if they were essentially one item, really would be nice to know.

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Well, the simplicity of this story probably won't even count here, but I'll tell it anyway. A friend brought me an inexpensive violin maybe six years ago that he had stripped and wanted me to finish in a darkish brown. he had no money (I seem to catch a lot of these!). I had heard of asphalt as a colorant, so I shoved a screwdriver in my pocket and hopped on my bike, and road around looking for pothole repairs. Inveriably, a pothole repair will have an area around the edges where puddles of asphalt have dried without a mess of gravel mixed in. I dug out a large marble size piece with the screwdriver, took it home and put it in a shot glass, and used just enough turps to cover it. Let it set a few days and then filtered it into another shot glass. I put about one ounce of the results directly into enough Tru-Oil to give the instrument 2 or 3 coats. To this day that fiddle has a warm, dark brown/gold finish and has not faded at all. Since then I've done this to a few instrumewnts I've built for myself, and the results have been the same (in fact, I have certain road repairs I go to depending on the color I want :P which seems to indicate to me anyway that not all asphalt is exactly the same). Anyway, I've never had a fading problem.

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  • 8 years later...

Has anyone encountered a situation in which coal tar has been applied to a stone sculpture as a adhesive medium for a mineral flake adhesion. I think I've encountered this system in analyzing an older Chinese sculpture but I am unable to find any referencing to this. If there any questions or comments please email me thank you

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