I read your reply to B.M. with regard to Trouble Spraying Inorganics. Even I was impressed by your depth of knowledge. WOW!
I have a comment or two regarding your reply to B. E. regarding tacky spots. I know that you edit your letters, but there was no question concerning the mass and structure of the part. My feeling is that 25 minutes at 325°F is just borderline for a decent size part using high solids. Wouldn’t 350°F be a bit safer? Also, are the tacky spots in the same area on all of the parts? Nothing was said about that. Perhaps there may be more mass in the area that remains tacky. During my 30 years in coating sales, I really enjoyed the challenge of finding causes and cures to problems. Always a pleasure reading your column first. S. B.
Thanks for your kind comments, S. B. I agree that there is nothing more fulfilling than finding causes and cures for problems. When I had a real job, my company had about 100 paint lines in nearly as many plants. We had powder coating lines, electrocoat lines, dipping lines and spray lines where we applied every type of coating available. While you were out there selling paint, I was solving the paint line problems.
You raised a couple of interesting questions and I agree that nothing was said about tacky spots being in the same place on painted parts. However, the key to my answer was that, according to B. E., re-baking the parts with tacky spots didn’t help. Therefore, raising the temperature from 325°F to 350°F would not solve the problem. Furthermore, the paint supplier would have recommended it. Again, I appreciate your comments.