The stages in the drying of paint film are identified by various methods. One in common use is to touch the drying film with the finger at intervals. In an air-drying paint, the first stage of drying is the formation of a thin skin to which dust particles do not adhere (dust-dry). The skin gradually becomes more rigid and is unbroken by light pressure of the finger, but feels tacky. It next becomes tack free to a light touch, but is still soft and impressionable (touch dry). Finally, it becomes fully tack-free and hard and capable of meeting with good resistance the impacts and abrasions it is likely to receive in practice.

Another simple method of measuring drying time is to sprinkle sand onto the surface of the paint at regular intervals during its drying period and note the time that elapses before the film is dry enough for the sand to be removed easily from the film by a camel hair brush. The film is then at a tack-free stage of drying.

An approximate method to measure the hard dry stage is to use thumb pressure sufficient to counterbalance a 5 lb weight on a balance, and measure the time at which the thumb fails to leave a permanent impression on the film.

Tape resistance time is a method applicable to refinish where masking tape is placed on the paint film for a given time (say 5 mins) and once the tape is removed no permanent tape mark is left.