Lead White glows under a black light?

Is that cool, or what!? Thanks!

George O’Hanlon, who owns Natural Pigments uses a similar method but with actinic lights used in large aquariums - much hotter - to test pigments and varnishes on paintings. He assured me that as long as the heat was not more than 100 degrees - well, you can read his letter on the demo part of this site.
He is a knowledgeable and well respected paint maker - I respect his opinion and that’s why I included his note to me.

I included the Wiki note on black light, for those who don’t know what it is or how it is made…not to prove that it dries oil paint. Most oil painters know that oil paint can take years to cure and thoroughly dry - through oxidation, cross-linking of molecules etc.,also that one should ideally wait 6mo to 1 yrs to varnish. I wasn’t trying to offer scientific proof - just a possible shortcut that might work for others, as it has worked for me.

It can be a good practice in patience to let your painting dry naturally before adding another layer, start other paintings as you watch that one dry or use alkyds/dryers to speed the process, however, I’ve been down that road and am grateful that I now have a practical system that works when I need it.

I’m not sure if it’s just the heat and/or the uv light being bounced all over the foil to mimic sunshine - the paintings are dry enough to work on the next day and or varnish. I use Conservator’s Varnish -similar to Gamvar- not mastic or dammar.

(I also can tell if my panel is lead primed or I’ve used lead white in places, ’cause it glows in the dark under the black light!

I’ve also lightened cleansed linseed oil inside the box after many days hoping to make sun-thickened oil. But that process happened much faster in the real sun in the middle of summer and I needed the space inside the box to dry paintings!)

I’m all for experimenting, but I’ve done my part on this one and just wanted to share the results. So even if my frog is deaf - I love getting a glimpse of the chroma rim on that black light!

BTW I’ve left paintings in the window to dry, when the ambient temp in here is no more than 68, and there’s definitely a drying effect near a window. Not a lot of extra heat, a lot more UV.

My opinion on the box - does it really matter whether it’s the heat or the light that dries the painting? The end result is that the painting is dry (not cured) for the next days work.

First of all, I did mention UV curing of certain resins, and amber is a resin. While certain resins are compatible with oils (alkyds are resin-based, and dry faster than oils), and even if I decided to coat one of my paintings with amber resin, I would only expect the UV to cure the resin, not the paint, based on my earlier hesitations.

But the question I have is related to your statement: “I got the original idea from Donald Fels http://www.ambervarnish.com after I bought some mediums from him.”

And 60-watts can make plenty of warmth in an enclosed space. The Kenner-Easy Bake Oven mentioned earlier, uses a 100 watt bulb and had to be recalled (http://en.wikipedia.org/wiki/Easy-Bake_Oven) due to kids getting burned from parts inside the oven. And it bakes a cake! And cookies! And fingers.

60 watts of black light bulbs (which use the additional electronic support of ballasts) may or may not produce the same heat as a 100-watt tungsten light, but for the sake of argument should generate about 60% of the heat inside an Easy Bake oven — adn we’re talking 8-hours or more.

Did you get the idea from him? Or did the idea come from you after you bought some of his mediums? Big difference, to me. It does make sense that is he has resin-based mediums that UV could affect drying time in paints mixed with resin-based media, but as a general drying box for typical oils, I am still in doubt mode.

That paintings dry faster in the sun (who in the world puts their paintings in the sun?!) does not eliminate the warmth factor as the drying accelerator.

I don’t doubt that your paintings have dried faster. I am only expressing my doubts as to the ’cause of the effect.’

There’s an old joke about a scientist testing his theory on a lab frog. He claps his hands loudly causing the frog to jump. He cut off one of the frog’s legs. Clapping made the frog jump again. He wrote his findings in his notebook. He proceeded with the experiment until all four legs had been removed, taking notes between each step of the experiment. Finally he clapped his hands repeatedly, then, nodding his head knowingly, he wrote in his notes: Removing all four legs causes total deafness in the frog.

The wikipedia link you offered is devoid of information about the effects of UV light on paint or organic oils. The other link suggests the medium you paint with contains additions of amber, which I don’t believe is, or ever has been commonly used by artists. Mayer believes that amber, being an extremely insoluble and intractable substance, was probably a generic term for various thick, heavy varnishes composed of cooked oils and resins (which may, but probably did not, contain small amounts of amber). The mixture was then rubbed into panel paintings warm, the picture then being exposed to the direct rays of the sun until dried. While the use of sun drying seems to confirm a UV light connection in this case, it also seems, as David mentions, to correlate just as well with heat. His suggestion of an experiment is an excellent one.

I remember (it’s been over 40 years now) using a few drops of “Rabbit Skin Glue” in my painting medium, which had a dramatic enhancement of the “drying” time of the painting. I don’t doubt there are other resins and additives that would have similar effects on drying time (and perhaps deleterious side effects, which is why Mayer warns against their use in general), and perhaps UV light has a direct effect on THOSE substances, I just doubt it has much of a drying/curing effect on the traditional artists oils and pigments.

Invisiable UV rays from the sun have worked for centuries.

Actinic lights will work, too, but more expensive and produce much more heat, as George stated in his letter to me. The black light lamps I’ve used are about 15w each, making a total of 60 watts. Yes, the lamps were an investment - about $20 each, but have paid for themselves many times over this past year I’ve been using this system.

I got the original idea from Donald Fels http://www.ambervarnish.com after I bought some mediums from him.

While I believe the box in question does accelerate the drying time of oil paints, and provides a dust-free environment in which to do so, I am suspect that the UV light waves radiating from a black light have anything to do with drying time, or if they do, they would not — in my imagination — accelerate the drying time significantly beyond that of the same number of standard fluorescent bulbs.

I suspect it is the raised temperature in the enclosed space that is accelerating oxidation and “drying” time. Something akin to the Suzy Homemaker Easy-Bake Oven. Oxygen is, as I understand it, a catalyst that causes linseed oil to change properties, hardening. If I am not mistaken specific resins are made for acrylic paints and some varnishes and epoxies which, by design but not inherently, harden or cure when exposed to UV light waves, as these particular materials react to UV light as a catalyst.

As pointed out, oil paint actually hardens due to chemical changes from oxidation, it does not ‘dry.’ Except for UV-curable paints specifically designed to do so, I have not heard of the average brand of oil paint curing from light radiation in the visible or invisible bands of the spectrum.

A curious test would be to make 3 boxes, 1 for UV lights, one for standard fluorescents and one for a heating element to set to keep the box at the same internal temperature as the 2 light boxes. My guess is they should all dry about the same time, with the only improvement left to make is to convert the heating-element box to a convection oven with some way to move the dust-free air within the box, or keep filtered air moving through it.

I am open to being corrected if my thinking is faulty. Since 4 black lights is an expensive proposition, I am wondering if someone can point me to any data suggesting that invisible UV light waves have any effect in oxidizing linseed oil.