Ask the Expert Question-and-Answer Archive

by Ron Joseph

October, 2003

Avoid Tiger Striping or Striping of Paint Finish

Q. I have noticed working with HVLP equipment I get a striped finish on large surfaces every so often. It appears like wet and dry areas. Is this a technique problem or equipment possibly?

A. Thanks for your question. It sounds as if you have the typical and common problem that I see in the field quite frequently. This is not a paint problem or a spray gun problem. Rather my guess is that it is due to your painting technique. When you set up your HVLP gun, make sure that the fan width is not too narrow or too wide. For instance in most cases a 2"-3" fan is too narrow, whereas a 10" fan is too wide.

Then, if you are moving down a panel when you paint it, insure that you overlap your strokes by 50%. That means that the orifice of your gun must always be in line with the bottom wet edge of the previous stroke. Suppose you are using an 8" fan, you will be moving your gun down by 4" per stroke until you have covered the entire panel. If you exceed 50% and move down 6" at a time, you can expect tiger striping.

You might also be arcing your gun from left to right as you apply the paint. Insure that the orifice of the gun is always perpendicular to the surface. If you angle your wrist from left to right, or sway your arm from left to right, you will definitely get the wet and dry finishes you wrote about.

Please try correcting these two techniques and let me know if they helped.