The other day I was bragging with my latest finds among which an antique frame in poor state of preservation. Now I’m back with photos from the restoration treatment. I wasn’t able to find much information on this subject on the net so I thought it would be interesting to share my experience. Not quite a tutorial, but I wanted you to see at least how I did it.
Antique frames are usually dusty and dirty. So the first thing to do is to clean the surface by removing the dust with a dry brush. This is done on both the surface of the plaster decoration and of the lacunas, with care to the parts that may move or detach from the support.
The next step is to consolidate the friable areas of the plaster with a solution of fish glue (or gelatin). The adhesive (a 10% solution will work) is mixed with water and then heated until it dissolves. Ideally this should be done in bain-marie to keep the temperature below 100ºC (212ºF), as boiling will affect the adhesive properties.
The solution is then applied by brushing in the friable areas or injected in the cracks or detachments of the plaster.
The large missing parts of decoration are reconstituted using molds of existing similar parts. I made the molds using modeling clay because it was what I had available, but silicone or a casting resin will work best. Generally the mold should be a bit larger than the missing part so the desired shape can be cut out once the plaster is dry.
Antique frames were made of plaster based on gypsum or chalk and glue but gypsum works best for the reconstitution of the missing parts as it has a shorter setting time. A bit of glue may be added to the gypsum to enhance its resistance and elasticity.
When the gypsum is dry the modeling clay can be removed. The piece can then be shaped to fit into the lacuna of the frame. To attach it into its place use wood glue (PVAc).
For smaller areas that can be remade without using the mold, a filler based on chalk and fish glue (10%) can be applied in layers with a brush until the desired shape is obtained. The same filler can be used for the cracks and lacunas formed at the joins between the original and the reconstructed parts. After drying, the surface of the fillings can be polished by sanding or smoothen with a wet cotton swab. The excess of plaster and other eventual marks should be removed in the same way.
Next step is to retouch the restored parts so they fit the original. This frame has golden metal leaf, so the new parts had to be gilded also. Metal leaf is applied by the help of an adhesive, but before applying it the surface must be sealed so the adhesive does not penetrate into the plaster. I used shellac applied in two layers as a sealant.
After all the restored areas were gilded, I applied a patina made of varnish and pigment. It may be quite difficult to obtain shades very similar to the original in case of metal leaf retouching. To ease the matching of the shades I sometimes use gold or bronze dust in combination with the pigments and varnish.
And voilà the frame after restoration.
Once the restoration practice took over my workshop I decided to work on another two frames at the same time. I’ll post some more photos soon.
Antique frames are usually dusty and dirty. So the first thing to do is to clean the surface by removing the dust with a dry brush. This is done on both the surface of the plaster decoration and of the lacunas, with care to the parts that may move or detach from the support. 
The next step is to consolidate the friable areas of the plaster with a solution of fish glue (or gelatin). The adhesive (a 10% solution will work) is mixed with water and then heated until it dissolves. Ideally this should be done in bain-marie to keep the temperature below 100ºC (212ºF), as boiling will affect the adhesive properties.
Antique frames were made of plaster based on gypsum or chalk and glue but gypsum works best for the reconstitution of the missing parts as it has a shorter setting time. A bit of glue may be added to the gypsum to enhance its resistance and elasticity.
For smaller areas that can be remade without using the mold, a filler based on chalk and fish glue (10%) can be applied in layers with a brush until the desired shape is obtained. The same filler can be used for the cracks and lacunas formed at the joins between the original and the reconstructed parts. After drying, the surface of the fillings can be polished by sanding or smoothen with a wet cotton swab. The excess of plaster and other eventual marks should be removed in the same way.
Next step is to retouch the restored parts so they fit the original. This frame has golden metal leaf, so the new parts had to be gilded also. Metal leaf is applied by the help of an adhesive, but before applying it the surface must be sealed so the adhesive does not penetrate into the plaster. I used shellac applied in two layers as a sealant.
