How to Prep Clean an Existing Finish for Paint or Stain

From GF University, learn how to prep clean old cabinets, furniture and woodwork for a new finish.

The most critical step of a furniture refresh happens before you open a can of stain or paint; it starts with cleaning and sanding. Some companies promote their products as "no prep." There's no such thing. Skip this step and the finish may fail. The General Finishes standard for a successful finish is it must adhere well and stand the test of time.

We prefer using a 50:50 mix of denatured alcohol and water because it does not contain phosphates like many commercial cleaners do, and it is inexpensive, readily available and does not require rinsing before prep sanding.

Cleaning an existing finish removes dirt, grime and many common contaminants, such as oil from hands. These everyday contaminants prevent good adhesion, which may result in chipping, peeling and flaking - all signs of a failed finish.


Prep sand an existing finish with a 220 sanding pad (our preferred method) or 400-grit sandpaper. Then wipe all dust from the surface with a damp cloth or towel. This further cleans the surface, removing built-up dirt, grime and oil from hands.


Dusting sprays containing silicone will also impact the appearance and adherence of a new finish. Silicone is almost impossible to remove. Oil soaps and wax can also cause adhesion failures.

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