Solving the zinc oxide problem

These were not problems (although there were others) when artists painted on rabbit-skin glue grounds, coated with lead priming, and used only lead whites since no other was available. Theoretically, and at considerable cost, one could go back to that if one could find enough lead white, and also get round the regulations that state it's only to be used for restoration purposes.... However, in the real world - we use Titanium dioxide and Zinc, on acrylic grounds. It's not that the problems aren't known about - the argument has been that the amount of Zinc in Titanium White is relatively small, and its negative characteristics are counteracted by the Titanium. I've never been sure how true that was - it's always sounded rather too much like an expression of hope than a confident scientific statement. However, in practical terms one has had to take it on trust - and if it reassures anyone, I've been painting in oil for 50 years, and have never yet had a painting crack or delaminate. I don't use Zinc White very often, be it said, and never in underpainting: although I've not been able to avoid it in Titanium White. It hadn't occurred to me that alkyd white contained no Zinc, and I'll look into that - the painter Stephen Higton, who used to show here, uses alkyds for all of his paintings and seems to do very well with them. There are going to be those here who will say you worry too much about this, and that your concerns are driven by the sites you visit:: whenever these subjects (including lightfastness) are raised, you get the "oh don't worry, I just paint and leave the manufacturers to sort it out" response; and some of them can get quite aggressive, masking their underlying anxiety and the fact that you've stirred it up. I don't know if you've yet encountered that..... but whenever I've raised concerns with manufacturers, those that respond at all (usually you just get Stephanie in sales, whose nearest approach to paint is what she does her nails with) are remarkably uninformative in a way that suggests they'd tell you more if they dared - or knew the answers any better than you did. So there are issues; and I'm careful only to buy canvases and boards with the same care I exercise in buying paint and brushes; there is research going on, notably by the niche manufacturers (Michael Harding, Rublev, Pip Seymour I suspect, and a few others), and I hope Winsor and Newton and Daler Rowney still have their chemists and research departments. But all I can offer is the anecdotal evidence that I've not known of an oil painting to delaminate since artists stopped using bitumen as a medium (in the 19th century), always provided it was constructed with reasonable care. I have an oil painting on Dalerboard, dating from 1973 - it was badly damaged in a house-move causing the paint to crack away from the edge, but the bulk of it is sound and it could be restored if I could be bothered: anyway - you couldn't chisel the paint away: you might be able to grind it down but it's never going to delaminate, and hasn't even cracked. I certainly used Titanium White with Zinc on it, and in impasto layers - stare at it hard though I will, it's stuck firmly to the board.

You're right of course that 50 years is no time at all in these connections - which is why there are no guarantees about the longevity of acrylics, or water-miscible oil paints, neither of which have been around for longer than half a century. The manufacturers think they'll survive, they tell us; but then,they're not going to be around to argue the point, and neither are we. Probably.... I'm not a chemist nor an expert on paint manufacture; and indeed, these are few and far between. I haven't yet checked, but I suspect you're getting your information from the Natural Pigments Forum. You have given me much to think about, and I see my next week at least is mapped out for me in researching further into this. In the meantime - a word from chemists, paint-makers, manufacturers et al would be useful, if one could be solicited. I wonder if this is something The Artist magazine, which has these contacts and the resources to pursue them, might look into ...... Dr Bulgin? Are you there?

Postscript: I don't know if you can obtain them where you are, but Rublev oils can be obtained in this country, and don't contain Zinc (as you will know, because the information is given at the foot of the first article to which you linked). I have been thinking of switching to Rublev whites for some time, and to other Zinc-free whites if I can be quite confident they're available - not all manufacturers list them informatively. I think you've helped me to make my mind up. Interesting, by the way, that of the large number of whites listed in the article, from Bloxx onwards, a great many can no longer be obtained or, as with Vasari, are prohibitively expensive - because of the restrictions on lead paints, and the closure of lead-making plant. All the more reason to be very selective in one's choice. It's also interesting to note two further things - one, the damage to paintings occurred at least in one case when the canvas was rolled: the brittleness of the Zinc caused the paint to snap like glass; and the fact is that such damage could occur when canvas is re-stretched, or the painting is cleaned; and two, the painting of Ophelia by Millais contains an area of Zinc White but has not deteriorated in any way - the suggestion being that Millais's painting technique may have been responsible for that.... he certainly wouldn't have used an acrylic-primed ground, of course..... I'm afraid there will be people here who will find this thread utterly uninteresting - but it fascinates me, and I wish I knew more than I do; so will continue to do my best to find out.

Makes sense, Syd. The way the paint would come off would be in small flakes around the areas of weakness - the edges of the crack, or the point at which two chemically antagonistic materials abutted. It won't peel off - as acrylic can, if on an oily surface. You'll remember the stories about Sir Joshua Reynold's paintings - there's a magnificent portrait of (I think) Lord Cornwallis: areas of the painting just slurped off, "crept", because he'd used a bitumenous resin that never dried. That won't happen - probably! - because of Zinc White on acrylic grounds, but the damage to the integrity of the picture could be just as bad, and would be likely to be insoluble. I don't know that people will still want to look at any paintings of mine when I'm singing in the Eternal Choir - they'll have to do something about my voice before letting me in - but I'd like to think they'd still be in one piece even when I'm not. Hence the level of interest I take in this..

These phenomena are well-known by now, and when you say that Rublev (or other) lead paints are not an alternative - not an alternative to what? They're certainly not an alternative to Zinc; and have been largely superseded by Titanium - preferably without Zinc in it. However, lead paints still have their adherents, of whom I remain one despite the issues that arise with them - I don't recommend using them throughout a painting, or substituting them for Titanium, which remains the safest white generally available - even if there are safer and better forms of it to be had if you go to the trouble. Few painters use lead whites - at least in proportion to the large number of people who paint. This is one reason for their disappearance across the board: trying to find Flake, Foundation, or Cremnitz White now is difficult, though not impossible, and expensive for reasons already discussed. You have embarked upon a commendable journey to find oil paints which, if not faultless, are at least less problematic - and at least to the extent that you may help to alert manufacturers that we require more research on their part and better products, I can only support you. You know as well as I do, and probably better, all the same that oil paintings change for very many years after they've been painted - they will do that; they have always done that; and I'm not confident that we're ever going to be able to stop them doing it, or that it would necessarily be desirable if we could. Practical advice to contemporary painters would be that they should avoid Zinc White - certainly in under-layers (although I would also avoid Titanium White there, possibly other than alkyd white); and that they should pay attention to the composition of the Titanium White they buy. I doubt that you need to warn them against the use of lead whites - those of us who use them are aware of their characteristics for good and evil; you have to search them out and pay a high price for them, which most people aren't going to do; and the methods by which they're made today differ from the way they were made in the days of Rembrandt, who used nothing other than lead white because it was all that was available. And there are many questions about the composition of his whites - other than that they were all based on lead carbonate - which are still being researched: you could lay your hands on Vasari Flake White, for instance, and tell yourself you're using the same paint as Rembrandt used if you wanted to..... but it almost certainly isn't (and doesn't of course claim to be). If you are suspicious of paints and mediums named after great artists of the past, well I share that suspicion: it's marketing, that's all. But this is an area beyond the fundamental concern to find paint which most of us can employ with some confidence: I'm much more concerned for those painters who use such products as "Liquid Clear", "Magic White", "Liquid White", whose work is going to deteriorate without the least doubt; and about the practice of painting in oil over thickly impasted acrylic, especially on stretched canvas.... but then, we can't easily choose that which we're going to worry about most: so I wouldn't seek to draw you away from your concerns. Incidentally, I wasn't recommending the Rublev lead whites or suggesting they were a better bet in terms of durability than Zinc-free Titanium, but that's where we came in.....

It might also strengthen the theory that Gamblin likes selling product.............. I can see nothing wrong with applying an alkyd ground, and it would produce a smoother surface on a canvas or canvas board (which can sometimes be incredibly scratchy). But not properly sealed with acrylic gesso alone? I doubt it. What do you think of Ampersand boards, in their various surfaces?