Atkinson Comments on Asphaltum

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Posted by Mike Jackson on March 09, 2004

Here are a few comments I saw in Atkinson's book about asphaltum:

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Asphaltum:
Never add oil to Asphaltum, it will retard the drying infefinitely. Never use it without the addition of a few drops of quick rubbing varnish to insure hardness.

Asphaltum is used for glazing on colors and gold and has a wide latitude in producing many degrees of tone value by applying it thin. Depth of tone is produced by repeated glazings, one over the other. Thin with Turpentine. Also used to "gloss face" lettering on show cards.

For Glazing Color for Shades and Scrolls on Wagon Work:
Asphaltum is first; must be used with a little quick rubbing varnish or it will "pull" up when finishing varnish is applied. Fine for splitting shades, on greens, white, chream and yellows.

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Mike

Sarah King

Mike -

Thanks for posting this. I've been working on putting together a complete mirroring kit - including a pan and rack and everything a beginner would need except the glass and the water. I've been wondering about getting the asphlatum backing paint to dry quick and hard. Now I know what the story is - but ...a few drops to how much ashaltum? Is this a matter of some is good and more is bad - would you have a more explicit recipe?

Thanks

Mike Jackson

Sarah,
Actually, I believe he mentions add the quick rubbing varnish to asphaltum for more permanent applications where you don't want it to self dissolve. In the case of mirroring, I believe you want the opposite. You just need asphaltum to protect the glass and hold the glue chip glue back from the clear glass. After doing the process, you then want paint thinner to easily dissolve the remaining asphaltum.

To answer your question, I would suggest about on thimble full of varnish to about a half full bathroom sized Dixie cup. If you add too much varnish, it will get clearer, but that is not necessarily a bad thing depending on the circumsatances. Atkinson often used Asphaltum as a warm "shadow" glaze. Rick did that, too, but he later preferred selling his Shading Black since it was a darker "blueish gray" when used as a glaze.

Mike Jackson

Mike Jackson - Asphaltum

When mixing your gold formula, you are mixing to well defined ratios and weights. I doubt any sign painter could have told you they add 10 ml of thinner to 2 oz. of paint or ink. They just add the thinner to paint til it "feels right". When Atkinson suggests adding "a little" quick rubbing varnish, we can assume he did it enough to just know how much to add without a measuring device.

You probably saw a bit of that when you watched Dave Smith mix up his tin solution. Danny told me he more or less mixed it up as directed and then adjusted on-the-fly depending on whether the gold was sticking to the surface or causing the gator skin effects.

Hope this loosy goosy answer helps!
Mike