1. What would be a good ratio of lead white oil paint to titanium white oil paint to get a stronger film than titanium white with more opacity than lead?
2. Do the benefits/charcteristics accrue according to the ratio of lead white or titanium or does a little bit of one or the other actually have a greater effect than one would expect?
3. How important is a strong film formation if your support is rigid such as an aluminum-composite panel (ie dibond, alumalite, etc) primed with an acrylic dispersion (Golden) and does not bend or move easily or expand with humidity?
4. Does the importance of a strong paint film stem from its common use on hygroscopic supports such as stretched linen? Is it as important if the support does not move?
Thanks for your thoughts,
Richard
Hello Richard,
Some points are a little subjective and dependant on context.
With the understanding you’re planning to paint on a rigid surface pannel primed with acrylic:
1. Not painting on canvas or souple surface, the flexibility change is of little importance.
However depending whether you’re mixing paints or making your own, be aware safflower oil used in Titanium whites can make them far slower drying than a genuine lead white would be. So if you’re just intending to make a white ground, be careful.
2. Opacity of Lead white is closer to titanium (than zinc) so the opacity change upon ratio is fairly linear and not a huge thing. Drying-wise, lead compounds are strong driers. I would expect a bigger difference on core drying time.
3. and 4. To avoid a misunderstanding, I would differenciate strength/flexibility of film and good film formation (siccativation or crosslinking). The former is more important for ‘living’ surfaces as you’re already clearly aware. On a metal pannel, it’s less of a concern, you could paint with egg tempera and don’t expect cracks.
The later film formation aspect means how much of a continuous ‘thermoset’ polymer the film becomes, becoming resilient to solvents and harder to damage. It’s a progressive attribute of drying. If you want something to last longer, the better your drying goes the more resilient it will become.
It’s more for the longevity and resiliency overall, regardless of surface.
I hope it will help a little.
First time on the forum so apologies for the rookie mistakes I might do.
Cheers,
