Before any restoration of the furniture is undertaken I need to identify the actual finish of the items. I also have to decide if the current finish is original and therefore appropriate for the piece.

Before applying any advanced techniques to help identify a finish it is good practice to gently wash the surface with warm water and a good liquid soap. Applied with a soft cloth to a small area at a time, rinsed with clean warm water and dried thoroughly, then using the following procedure in aiding identification of finish:

 

1. Shellac finish.

A new shellac finish is bright, translucent and thin. A surface that has had shellac applied using a "French polishing" technique will appear glass like and without any signs of brush-marks or sanding.

Neither of these finishes will remain unmarked for very long. All shellac surfaces are vulnerable. They will decompose with heat to form white opaque marks (heat rings). Water left on the surface will result in areas of white semi transparent polish. Bruises and scratches are emphasised by the broken and flaked finish at the edge of the scratch and the rim of the bruise.

If the piece is genuinely old the likelihood is that the piece will have been finished with shellac. Find a spot, which is unobtrusive, and carefully wipe a piece of clean cloth, dampened with Methylated spirit. If the surface is shellac it will soften and lose its shine.

 

2. Oil based Varnish.

This is a more durable finish. A slightly flexible quality prevents the finish from being so easily damaged by bruising or scratching. A piece that you know has had a lot of use but does not show the marks outlined for a shellac finish, is likely to have been finished with a varnish. Look for the runs and puddles of varnish that collect in areas difficult to work with a brush.

A varnished finish will be unaffected by Methylated spirit therefore use a clean cloth dampened with white spirit/turpentine. This should soften the surface.

 

3. Cellulose.

A very modern finish that is hard and difficult to mark. Usually applied by spraying, it forms a brittle, glass like film on the furniture.

Cellulose will be untouched by both turpentine and Methylated spirit. However if in doubt by visual assessment a clean cloth dampened With cellulose paint thinners will soften the surface.

 

4. Wax polish.

A lot of very early furniture was finished just using wax in many varied forms. A wax finish can be scraped and marked with a sharp edge. Wax that has been exposed to heat will decompose to a crumbly, white opaque appearance.

Use a clean cloth dampened with turpentine. This will soften the wax and the cloth will remove the finish leaving a clean wood surface.

 

5. Oil finish.

Natural vegetable oils have been used for wood finishing for many years. The most common oil would be Linseed but others are Walnut, Tung, Danish, or a combination called "Finishing oil" Correctly applied, oil gives a beautiful result.
Wiping the surface with a clean cloth dampened with turpentine or Methylated  spirit will remove any dirt or grease and leave a matt surface With much of the finish below the surface of the timber, it appears thin and yet appears to penetrate deep into the fibres of the wood.

The actual finish cannot be removed by methylated spirits, turpentines or even stripped off. However it can be restored with effort. after cleaning, by application of fresh layers of oil.