Plastisol Drips

Question:

I am contacting you regarding the clinic question entitled “Plastisol Question” from R.E. in the July 2002 issue.

My company manufacturers precision dip molding and coating systems for a variety of industries. The drip that R.E. describes is primarily due to a lack of precision control of his dip axis. With the proper dip axis speed and mechanical control capability, that drip can be virtually eliminated. The preheat oven capabilities also factor into the equation. If the part is not completely “soaked” previous to dipping, there may not be enough latent heat to solidify the material during withdrawal.

I would appreciate it if you could either have him contact me or pass along his contact information, and we could address his problem. C.O.

I am not sure why I am contacting you now, except that I just wanted to tell you that I enjoy reading your column every month. I don't know how you keep your sense of humor when you get the same questions month after month. The advice you give is good, but people never seem to get it or don't want to get it. They expect you to solve their problems for them, so that they won't have to expend any effort other than e-mailing a message to you. This month (October 2002) you addressed four questions. In three out of the four you made the point that pretreating the metal before it is painted is critical to the success of the whole process. Even though you hammered hard on this issue this month, I bet you'll get more questions regarding this issue the following month. Anyway, keep up the good work. I look forward to reading your column every month. N. F.

Answer:

I don’t know, C.O. I’ve been around all types of coating operations including plastisol dip coating for nearly 50 years. In several plants, we made plastisol “boots “ for covering bus bar joints. No matter how hard we tried, we couldn’t get rid of the drips or fatty edges as they called them. We had all the power and might of the Westinghouse Research Labs trying to solve the problem. We had Ph.D.s and Post Docs. We had guys who were so smart they couldn’t find their way home after work.

However, maybe you discovered the solution to the problem. On the other hand, maybe you just want a trip to Mexico. That’s where R.E. works. In any event, I will forward your e-mail to him. I hope you can help him.

Thank you for writing and don’t take offense at my aforementioned remarks, they were made in jest. I am sure there have been developments in application equipment and techniques in the last 25 years. It has been that long since I was involved. By the way, there is no longer a Westinghouse Research Labs and all their power and might are retired, dead or both.