Lead Carbonate



For many hundreds of years, lead carbonate has been recognized as the most important and crucially useful pigment to use in oil paint. The fact that it was almost the only white pigment used before the introduction of zinc oxide and titanium dioxide is the least of it.

White lead paint (cremnitz, flake, silver white, whatever it's called) has an excellent and unusual combination of characteristics. It's a warm and slightly transparent white, which doesn't overpower other colours when they're mixed with it. It's very tough yet flexible, and it absorbs relatively little oil to make workable paint. Titanium white is a very good but very different pigment, which can't compete with lead in these structural qualities, and zinc white even less so. Also, lead paint should dry extremely quickly because of its low oil absorption, though the commercial stuff usually doesn't because of how it's made. To the best of my knowledge, lead primer is still by far the most stable and durable ground to use on canvas. But the way it behaves on the surface of the painting is just as important.

If you use traditionally made lead paint (not necessarily what you buy in a tube), you will discover that it behaves very strangely. It is both thixotropic and extremely stringy; this combination of characteristics can create very distinctive textures, and can sometimes make painting easier. The thixotropy means that its viscosity actually changes while you're using it, so that even quite liquid paint can be built up to some extent while it is wet; with normal paints, this only works if it's very stiff, and looks completely different. The term "liquid impasto" sounds like an oxymoron, but it is possible with lead. This characteristic, combined with the extreme stringiness, can also allow you to paint details without them looking precious, by trailing the strings around and piling them on top of each other, bringing the painting literally if slightly into the third dimension. Good lead paint can often help you achieve the best of both worlds - control which appears to be messy and accidental.

My lead white on a glass plate...

...and on a painting in progress

I buy lead carbonate powder and grind my own paint. If I could, I would use this home made stuff almost exclusively. It has all the ideal characteristics mentioned above, as well as yellowing less than any commercially made lead paint that I've ever used. Sometimes, depending on the oil used, it dries almost as quickly as an umber colour. A reasonably thin layer will dry to the touch overnight, the convenience of which cannot be overstated.

I always wonder why commercially made lead paint rarely has these traits to any great degree. It invariably dries relatively slowly, and yellows a bit more. Even the most traditional and "lead like" tube paints that I've ever tried were only slightly stringy, and not especially thixotropic. It usually seems as if the manufacturers have tried to shorten the paint (ie. make it crisp and buttery and stop it from leveling like enamel), and to increase the shelf life by slowing the drying speed. One can't entirely blame them for this; if someone tried to sell my paint, it would probably clot and thicken in the tubes, and the majority of people would probably hate the texture because they're not used to it. And don't misunderstand, many commercial lead whites are very good for what they're intended to be. I use Michael Harding cremnitz all the time, and once in a while I do actually need a white with a short, modern texture.

Most often, though, when I use store bought lead, I have to make a considerable effort to mitigate its boring behaviour and make it dry fast enough to overpaint it. So how do these companies manage to get lead paint to behave so disappointingly like other paint? Is it done with stabilizers and additives? Many highly reputable paint makers assert that their lead paint contains only pigment and oil, and I don't think they're all lying.

Sometimes you will find a discussion in an internet painting forum in which someone complains that lead white never dries quickly, even though all the textbooks say that it should. Someone else will then assert that modern industrially made lead carbonate isn't as good as the historical pigment. It is true, apparently, that there are several industrial processes for making it, and some end up with a very pure substance. Traditionally made lead white was always impure, including a third or more lead hydroxide, which made it dry better, among other things; so pure lead carbonate is not as good. But the current standard process in the paintmaking industry (as far as anything involving lead is standard today), produces a ratio of about 70% carbonate to 30% hydroxide, which is almost perfect. I know for a fact that it makes really excellent traditional paint. Do all these prestigious paint makers use substandard pigment?

I used to use Studio Products lead pigment, and I once bought some of their paint. As with everyone else's, it dried fairly slowly; their pigment, however, would make beautiful, old fashioned looking paint that dried in no time. They said it was the same pigment, supplied by Hammond Lead Products (who have now stopped producing it, by the way). Whether you believe them or not, they also said their paint contained nothing but lead carbonate and oil. So maybe the explanation is not the pigment, but the oil they used.

When I make paint, the type of linseed oil is very important. I think many people who are otherwise very knowledgeable drastically underestimate the difference this makes. When I use Kremer's Swedish cold pressed oil, the resulting paint is extraordinary. It's quite thixotropic and extremely stringy, yet it retains brushstrokes fairly crisply. No other oil I've tried combines these seemingly contradictory features, at least, not to anywhere near the same degree. Other cold pressed oils produce very good, stringy, thixotropic paint with low oil content, but always without the relative crispness; they level out to an enamel-like surface with little or no trace left of the brush-strokes. And you certainly can't use just any given industrially refined oil from the art store. I've been told that refined oil works well with lead if it has a high acid number (I barely know what this term means). Whether it's as good as what I use, I don't know, since I've never tried. There may even be significant differences between different brands of alkali-refined oil. But using some kinds of art-store oil will result in unusable paint. I once stupidly tried grinding lead in Winsor Newton alkali-refined oil; the resulting paint absorbed about 166% the usual amount of oil, had a greasy consistency, took forever to dry, and had no trace of the peculiar characteristics which make lead so useful.

I made a mess; obviously commercial lead whites are not quite like this. Again, they're often very good for what they are. But maybe the oil is what makes them so different from traditional paint. So that should mean that if you squeeze out a sample of store-bought paint onto some cardboard to drain off the original oil, replace it with cold pressed oil, then systematically repeat the process many times, so that the percentage of original oil becomes totally negligible, you should end up with lovely, stringy, low-oil, fast drying, old-fashioned-Rembrandt-like paint, shouldn't it?

Guess what... it doesn't. I tried, and only managed to waste an hour of my life; maybe those paintmakers are lying, after all. I give up... for the moment.


* * *


Anyway, here's the thing: lead is decidedly toxic and quite dangerous. I assume it's much more dangerous than, say, cadmium, cobalt, or the manganese in umber colours, which nobody worries about anywhere near as much (though I would be curious to see this confirmed by a doctor).

If you use lead paint in the studio, you should avoid putting brushes and things in your mouth, and you should wash your hands and fingernails when you're finished. If your studio is actually in your house, you should be all the more careful. If you have children or animals around, you should be even more careful still, since apparently small mammals of any species are more susceptible than adult humans.

The point is, as far as the wet paint is concerned, you actually have to eat it to do any harm. It doesn't penetrate your skin easily, and there are no toxic vapours. As long as one is careful to avoid ingesting lead paint, as one is with many toxic yet commonplace household substances, it poses no real threat. The more significant danger is from the dry pigment.

When I make my own paint using dry lead carbonate, I do it in the garage. I wear a respirator with lead/asbestos cartridges. I make sure not to get it on my clothes, and I'm even careful to be gentle when I handle it, so as to prevent the dust from floating around in the air. When all of it is wetted with oil, the hazard is vastly reduced. In the studio, as long as you are tidy and remember not to eat it, the only real worry is if you sand the dried paint. I never do this, but I do often scrape it with a modified razor blade; this is something to be really careful about.

I wouldn't suggest taking any lesser precautions than these. But you have to remember, for many centuries, painters ground this stuff in their studios every day, with fewer safeguards. This is not because they were utterly stupid. Lead is toxic, but it is not plutonium.

If, in conversation with someone at an art supply store, I happen to mention that I grind my own lead paint, it tends to elicit a slightly shocked expression, followed by the uneasy suggestion that this is dangerous and that I should be very careful. Well, yes, this is an indisputable fact, but the expression and emotion accompanying it would be more appropriate if I said I was cooking homemade napalm on my kitchen stove.

The people who run serious paintmaking companies, and who still actually make lead paint, usually have a sensible respect-rather-than-fear attitude. But not always.

Kremer Pigmente is a great company. They sell pigments and paraphernalia which are often obscure, archaic and fantastic, like Afghan lapis lazuli, and real Tyrian purple. They also carry really good cold-pressed linseed oil, by the way. But look what it says on their website if you try to buy their lead white in oil:

"Only permitted for the restoration of art works as well as historically protected buildings, only if the use of substitutes is impossible.
The sale of this product is legally restricted.
Please send us the required proofs of professional use together with your order."

This is on the site for Kremer USA, not the parent German store. Maybe it's just a translation of what's on their EU site, but if so, it seems they've tied themselves up in knots that aren't even required by US law. God only knows what regulations they have over there, but in North America it is permitted. It's not legally restricted here, and lots of companies sell lead paint, even if very few sell the dry pigment. And certainly, no-one here requires proof of professional use; many serious painters wouldn't even be able to provide it. It's disturbing that they willingly adopt and promote this attitude in the USA when they don't even have to; they, of all people, should know better.

But what's really important about the above example is not the fact that I'm petty and resentful that they make it so hard to buy their paint (which I am). Rather, it gives some idea of the mindset in Europe. In Canada and the US, trying to get lead is frustrating, and lots of people are paranoid about lead, but at least Government regulations are not quite as active and direct a threat. The problem here is mainly economic. Although artists' paints were exempted from the lead paint ban in the 70s, fewer and fewer lead companies produce lead carbonate, because the art materials market is too small to make it worthwhile. Every time one of the few remaining US lead white producers stops making it, the price goes up. And of course, another factor in its expense may be the cost of ever increasing safety precautions for the workers.

But the situation across the Atlantic seems to be worse. Apparently the last European manufacturer of lead carbonate has now stopped making it, and various paintmakers are either raising their lead white prices drastically, or dropping it altogether. Michael Harding has a special page on his website outlining the problems he's having, saying that his potential new non-European lead carbonate supplier is charging an inflated rate, and that new EU legislation makes it virtually impossible to import an adequate quantity of the pigment from outside Europe. Apparently, there is also insane EU child-safety legislation that lead white cannot any longer be sold in tubes, so he's now putting it in cylinders which fit in a caulking gun. I suspect the new packaging itself will add to the cost, and it also means he can't sell it in small quantities, either. I'm sure it's a similar nightmare for all the other EU paintmakers who haven't just given up.

So, lead white, which is arguably the most important and useful pigment in the history of painting, and which should be a bulk staple, is rapidly becoming obscure and horribly expensive. That is why I was so overjoyed to discover the following:



George O'Hanlon's company, Natural Pigments, started making honest-to-God old-fashioned Dutch process lead white a few years ago. They set up an ugly pre-fab metal garden shed, filled it with three feet of horse manure, and added dozens of traditional earthenware pots containing lead metal. Each pot is filled about a third full of vinegar, while a long, flat strip of lead is loosely rolled into a coil and suspended above it. The vinegar fumes corrode the metal to make lead acetate, which in turn is converted to lead carbonate by the CO2 and water vapour released by the rotting manure over several months. One variation or another of this method is how most lead white was made for hundreds and hundreds of years. It's supposed to handle somewhat differently and absorb less oil than modern lead carbonate, due to the larger and more irregular particle size.

I've had some of this Dutch white for quite some time, but I confess I haven't actually got around to using it yet, due to its exceedingly precious nature. Because they make it on such a small scale, it's really expensive. I need this stuff in vast quantities, so this doesn't directly solve my general problem.

But at least it gives me some assurance that I'll never be forced to give up lead pigment. If it ever becomes too expensive or unavailable, and if I ever have to build my own shack full of horseshit and terra cotta pots, well, I won't be happy about it, but I'll do it.



Copyright © 2012 by Harry Steen