I’ve started the next batch of paint experiments for the cupboard I am doing for the MFA Boston. Their folks in the lab there have been working on some analysis of the painted finish of the original, and I have been trying to then translate their findings into something I can execute in the shop.
The gist of it, as I understand it, is that the pigments are mixed in “proteinaceous” material, (most likely animal hide glue), then covered with a natural resin varnish, with some pigment also mixed in that. So for this white oak panel, I painted the background with red iron oxide & bone black mixed in thin watery hide glue. then the next day I mixed a tiny bit of damar varnish with some turpentine, and tossed in just a few crumbs of red iron oxide…
It’s more apparent on this red oak framing stock. The first photo is just painted, the surface of the oak is unfinished. The next is painted then varnished with a slight amount of pigment, so the surface gets a thin translucent reddish color.
Here’s a piece from the existing cupboard base. The mix of the paint seems very gritty to me, so I have not used a muller to grind the pigment. At first I just used a pallette knife, on this batch I just mixed the pigment in with a brush. First thing I see is that I have switched the locations of some of the red/black backgrounds…and I need a few more pricked holes to highlight the carvings. that’s why these are still samples.
I’ll run all this by the folks at the MFA and see if I’m heading in the right direction. While we now know with some certainty what the finish is composed of, we still are left to fiddle around with what it might have looked like – with no way to ever tell if we are really on the money…but hopefully it will be close. No squiggles or dots on this batch…
PETER FOLLANSBEE: JOINER’S NOTES 
Dear Peter,
I apologize if I am suggesting knowledge/ and technique which you have already tried or is on your list,or has even been ruled out already, and it is with great humility that I venture to do so. I read in your post that the folks at the MFA Boston isolated a “natural resin varnish” with a little pigment mixed in. Have you tried a Copal (resin) varnish or an Amber (resin) varnish- which are cooked in oil as opposed to the Damar resin which is dissolved in turpentine spirits? In my limited knowledge, these “cooked-oil” varnishes were more in use during the seventeenth century than damar. Obviously damar is much cheaper to obtain and easier to work with and make- for the sake of experimentation than its more ancient cousins. Thank you so much for your dedication to the integrity of your work, and for making so much available to the public.
With great respect,
Jack
Jack
no problem at all with you speaking up…I appreciate it. I have not tried copal or amber…I just used Damar because I had some around. The varnish part is literally another whole layer, and you are probably on track with your suggestion. At some point soon, I need to get on with the actual cupboard’s finish, and I hope to learn more about varnishes as I get closer to the final finish.