To take care of your furniture, it can be important to know what type of finish was used on the wood. If you suspect that your finish is polyurethane, but not quite sure how to determine it, here are a few tests you can perform on your furnish to tell if it's finish is polyurethane.
The Scratch Test
One method of testing the finish is by taking a small knife to part of the finish and scratching off a piece. If the finish crumbles as you scratch it off, your finish is polyurethane. If you would like to keep the finish intact, this is not the best test to perform. However, if you are planning on refinishing your furniture and need to identify the finish so you can remove it, this test is perfectly acceptable.
The Water Test
For this test, place a drop of water onto your finish and let it sit there for 10 minutes. If the drop of water turns a creamy white, then the finish is not polyurethane, but rather a wax finish. Otherwise, your finish is polyurethane.
The Mineral Oil Test
The final test you can perform is placing a drop of mineral oil on the finish and let it set for three minutes. Wipe the drop with a cloth and check to to see if the cloth is stained yellow-brown or feels waxy. If either of these is the case, your finish is not polyurethane but rather a wax finish.