They also provide instructional info on using their products, something that we hold in high regards around here. I clipped a little of it for you to review. It is below. Metro sure seems to have it together, especially for the roundy-rounders out there. How to Prepare Surfaces for Lacquer or Enamels Lacquer and enamels require a little more prep work.
Results are usually best if are stripped completely of old paint before applying new color.
Especially surfaces like doors with grain. Use a high Quality paint stripper making sure to follow the directions masking surrounding areas to protect them. Once surface is stripped, use a wire brush to remove any paint remaining. Apply a primer in thin coats and build up an even coat without filling in any texture. For Surfaces that do not need to be stripped, sand area with 180 grit dry or 300 grit wet or finer.