this months Paint Pro, by the way is another excellent publication for up to date painting tech and procedures. Pro and novice both.
I remember many questions in the past on how to tell which finish is on your particular wood project. the need to know is for how to clean it and repair it.
Here is a very good procedure to tell. First, Clear finished on wood maby be soft or OIL and they may be hard which is either lacquer, shellac, or poly.
this is the test:
1) Rub a few drpos of boiled linseed oil into the wood. If it absorbs, the wood has an oil finish. If it beads up, the wood has a hard finish.
2) To identify which hard finish, rub acetone over a spot in a gently circular motion. Lacquer will disolve in thirty seconds with rubbing. Poly finishes will shed acetone like water. Varnishes and shellacs will turn to sticky gel like substances in a minute or two.
3) To determine if a finish is shellac or varnish, sprinkle a few drops of denatured alcohol on the wood. Shellac dissolves quickly, while varnish reacts very slowly.