I am looking for help. I would like to reproduce the carved adornments on antique picture frames. I have made a poly/latex mold, but I am unable to find a suitable filler. I know there is a receipe for mixing the compound used for the originals. I have tried plaster mixed with a polymer and sawdust mix, but neither can be sawn & sanded effectively. Can anyone help me with my search? Thanks Joan
on the wall in 15 minutes
If you go the autobody filler route in an enclosed shop, a proper fitting respirator is suggested.
Try to get hold of the book "Framing & Gilding" by Paul Curson
Another book that I've heard recommended, but not read myself, is Loeffler's near-mythic "Step-By-Step Compo and Mold Making"
It's called "compo". There are several recipes, and searching for "compo" and "gilding" should turn some up.
Compo is basically a plasticised gesso, with some of the properties of sealing wax. Like sealing wax it's a "thermosetting thermoplastic" - it melts and can even be re-melted, but it only offers its ideal behaviour on the crucial first hot working (so it'll give trouble if you try to re-use it). It also shrinks on cooling in a controlled manner, so that it de-moulds easily. Sealing wax is usually a shellac and a wax, compo is a mixture of an oil and a resin.
The ingredients in all "real" compos are rabbit skin glue, whiting, linseed oil and resin. Distrust any that aren't. The precise materials vary. Whiting may be chalk dut, or kaolin. Resin might colophony (rosin), sandarac or even shellac. Processing of the linseed oil can vary. Some have even had white lead (litharge) in them, but I wouldn't advise that.
You can buy good ready made compo from Baggot's, which is probably the best option.
What I'm trying to say here is that I've lost by bl**dy recipe for it. Just spent two hours pulling my filing system apart and I still can't find it. 8-( I'll have to go and borrow "Framing & Gilding" again, which is where I got it.
Anyway, you boil the stuff up and it goes doughy. You've got the ingredients, experiment. AFAIR, last time I did it I melted the rosin in the oil (use the workshop hotplate, because it stinks and there's a fire risk), then stirred it into rabbit skin glue over my bain marie. Add some whiting to the rabbit skin glue as an emulsifier before adding the oils, then add the rest afterwards until the consistency is right.
Once you've made your compo, separate it into handy sized lumps and allow it to cool. Store cool and especially dry. When you're ready to use it, heat a lump by working it in a pan over warm water. Keep it dry, or it goes sticky and you'll not get it out of the mould.
When moulded and cooled, it's ready to apply. Steam the back and the rabbit skin glue in it should be adequate to allow it to be applied (if it isn't, wet it with gilder's liquor (30% alcohol in water) first).
The proportions also vary, to give different wam flexibilities, depending on what you're using as a mould. If you use a modern silicone mould (talk to the incredibly helpful Smooth-On company) then you can have a flexible mould and a rigid compo.
Compo is equivalent to gesso when applied, so you apply bole directly and gild on top of it. It can accept either water or oil gilding, unless you've re-heated it and used up all its "stick", then you have to oil gild it.
-- "Now he's got himself into a nice mess. That's what hapens if you start making a fuss of the Groke" - Moominpappa at Sea
On Thu, 15 Jan 2004 21:12:31 -0330, "Dan Parrell" brought forth from the murky depths:
Yeah, that'd do it. The Smithsonian Institution might use some other techniques, though. ;)
Compo is the name of the compound you seek. I found it in a gilding book a couple years ago and took a JPG of the gesso and compo recipes. Check your email, Joan
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