by WOODWEB's Finishing Team:
John Buries and Bob Niemeyer
Q. I run a flat line finishing system for wooden blinds, and I'm ending up with a wavy finish......any ideas?.
A. John Buries responds: When you are flat-line flow coating or "curtain coating," there are a number of variables that can contribute to a flawed or wavy finish. First of all, creating a wall or curtain of paint that can be up to 52 inches in length and holds together in a continuous film means precision equipment and properly formulated paint. When you pass the piece to be coated through this wall at a high rate of speed any air or break in the curtain will show up as a flaw.
Usually waves or tiger stripes mean there is a variation of gloss caused by inconsistent film thickness.
Check the doctor blades for any nicks, scratches, or a build up of dried coating. Even a small flaw in the blades can create problems. You may not see a break in the film, but the application of inconsistent film thicknesses can create gloss variation across the panel. Here are a couple of things to watch for that will help keep your finish smooth and consistent: