Note 08
Light, heat, and the finish on the surface
A London room can fade one side of a cabinet and bake the other if that other side is the radiator. The finish decides whether you are looking at a film, a wax, or paint — and whether sanding is even a reasonable thought.
Published · Updated
Daylight
The window keeps a record.
Light changes colour slowly and unevenly. The side that faces the glass goes first. A book, a runner, or a lamp base leaves a shape when it is moved. That shape is the evidence. Take the photograph before you rearrange the top.
Some woods shift hue in light as well as fade. Do not expect a hidden inside and a sunlit door to match after years, even if they started as one batch. The surface wear note shows how to photograph the difference without calling it dirt.
Heat
The radiator dries one face.
A radiator under a window is a normal London arrangement, and it is a harsh one for a sofa back or a cabinet plinth. The near face dries faster than the far face. Solid panels can cup. Veneer glue can let go. Leather on the radiator side can feel harder and crack sooner. Leave an air gap if the piece can move. If it cannot, note that in any description of the damage.
Seasonal movement from this drying is covered in timber movement. Blisters in a thin face are covered in veneer and solid wood.
Finish families, in plain language
These are groups, not brands. A single piece can carry more than one: paint over an older varnish, wax over a film, polish over dirt.
Oil
Often in the surface rather than a thick skin. It can be renewed in a small area more quietly than a film, and it offers less resistance to water. Rings still happen. Identify it only if you already know what was used. Guessing and pouring a different oil on top makes a sticky mix.
Wax
A soft surface layer. It marks, it shines where hands rest, and it is not a moisture barrier. Wax over a finish that has not cured, or silicone wax, complicates anything done later. If the surface feels greasy, say so before any other product goes on.
Shellac
A traditional film that water can turn cloudy and alcohol can dissolve. A white ring on an old polished table may be in this family. Alcohol is not a casual cleaner for it. The cloud and the solvent are different events, and this page does not give a stripping method.
Lacquer and varnish
A film. It chips at edges and can craze. Factory films are often difficult to blend invisibly. A chip filled level may still read in raking light. That is a limit of the material, not a failure of attention.
Paint
Paint hides grain and chips back to it, or back to an earlier colour. On older furniture and joinery, paint may contain lead. Do not dry-sand it into dust in a home, and do not heat it so that it fumes. If you do not know the paint, leave it intact and take advice from someone who handles older coatings. A general website cannot test your paint from a photograph.
If you use a finish product at home
Read the tin, including the ventilation line. Solvent finishes need air. Do not sleep in a room you have just coated. Do not mix products to use up the ends of tins. Cloths used with oil can heat as they dry. Spread them out to dry, outdoors if the tin says so, and do not pile them in a bin while they are wet. That is a fire precaution printed on many oil products, and it is worth following even when the job felt small.
Labels, not this page, are the instruction for a named product. If the piece is old, small, and the finish is unknown, doing nothing this weekend is a reasonable outcome. The disclaimer and the catalogue are the routes back to the rest of the desk.