I’ve been researching traditional painting methods and recipes, and painting on copper has caught my interest. After reading several documents analyzing different oil paintings in various states of preservation, I noticed none of them mentioned the use of chalk in their ground layers. Based on these sources, it seems the ground was composed only of lead pigment (often mixed with umber or ochres) and oil. Is that correct?
I plan to prepare my own ground for testing on small copper plates. My approach is to mix Old Holland’s Cremnitz white with some linseed oil. Could you recommend the ideal ratio of these ingredients to ensure strong adhesion to the copper, creating a durable film that will also provide a stable base for the subsequent oil paint layers? This mixture should ideally support excellent adhesion for the paint layers that will follow on the substrate.
Additionally, I’m curious about the possibility of adding heat-bodied linseed oil or stand oil to the mix. Would this enhance the ground’s strength and archival quality? If so, would it be advisable to incorporate any of these oils into the mixture, and in what proportions?
Thank you so much for your time.
Hello there,
The point of the ground was to give a starting colour, opaque to hide the surface and genereally white. So there would have been no point for chalk in grounds.
Lead white’s rather siccative so I’m unsure there would have been an added need for umber and ochres to accellerate it, but why not.
A cremnitz white should already be a rather ‘fat’ colour. Why would you want to mix it with more oil? The principles of oil painting genereally summarised and simplified as “fat over lean” rule. Although the context on metal is different from canvases, it still would suggest you’d rather lean your ground with a hint of spirits instead.
Adhesion to copper should be rather good in general, but there’s metal copper and metal copper. Is it mirror polish or sanded? gritty? Passivated?
The better grounds to provide stable base for subsequent layers and durable film would be slightly porous, with “tooth”, so not overflowing with oil that will make it smooth and shiny (and more likely for the next layer to lack adherence and delaminate).
Polymerised linseed oils would in theory enhance the ground’s flexibility and durability to some extent, but they are difficult to dry thoroughly in thickness so it’s best to keep them for the later layers.
I think you’ll be safer buying a good quality gesso than inventing your own.
Good experimenting to you.
Lussh
Hello Lussh,
Thank you so much for your reply.
The reasoning behind my thought of adding more oil to the Cremnitz White for the ground was based on the potential low amount of oil in the paint. I contacted Old Holland, as they claim their Cremnitz White to be suitable for grounds, in order to get more information on the paint recipe, but I have received no reply yet. They claim their Cremnitz to have <90% pigment content. I am a bit concerned about the presence of solvents being a potential hazard for the copper panel, but I guess a tiny bit would not be harmful.
As for the copper itself, my idea is tu use 99,9% pure etching plates, sanded and degreased with isopropyl alcohol to enhance adherence, just as advised in the rigid supports document.
As of your suggestion, it would be ideal to purchase a pre-made oil ground, but as far as I have researched, only Rublev and Williamsburg have available lead grounds. Rublev's has three siccatives (calcium, cobalt and zirconium), plus an antiskinning agent and chalk; I find such mixture overcomplicated and unappealing. As of Williamsburg’s, it also has chalk and a bit of cobalt siccative on it, but the main problem is that I cannot purchase it here in Spain. Also, there is the minor concern of cobalt and any other siccative reacting with the copper.
Is there any other, purer if possible, lead oil ground you know of I could access? Otherwise I plan to make my own lead oil ground with pure lead white pigment and oil, the same way traditional recipes were.
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