Paints & Coatings Resource Center

Ask the Expert Question-and-Answer Archive

by Ron Joseph

June, 2009

Issue with Paint Before Assembly

Q. I have a problem with paint before assembly, the issue is as follows:

  • Currently all parts in the target process have a finish coat of paint applied before assembly. The intention of the paint-before-assembly (PBA) process design is to eliminate the need for costly masking and painting of the assembled unit and to allow the painter access to all parts of the mechanism which may not be accessible after assembly. Also PBA protects chrome cylinder rods and other precision parts that should not be painted, from the risk of being painted when the unit is painted after assembly. The PBA process is not working as designed. Therefore painting is done before the assembly and due to many factors in the assembly and installation process and repainting has been done after assembly.
  • Repainting is needed because of heavy metal scratches and due to improper material handling.

Could you please provide me some suggestions and counter measures to improve the process.

Any suggestions or ideas with greatly appreciated.

A. I don't know enough about your process to be able to give you much helpful advice. For instance, I don't know why you are having so many issues with damage from material handling.

Are you using a hard, abrasion resistant topcoat, such as a two-part polyurethane? Although such coatings reduce damage, they are not foolproof and some touch-up is still required.

You might consider applying a soft rubbery strippable coating to all parts immediately after they are painted. If you select an appropriate coating it will withstand most scratches during the assembly process. I have seen such coatings used with limited success. They are able to prevent screw drivers and other tools from scratching through to the decorative topcoat. One problem that can arise is that assembly workers often like to pick away at the coating, removing small pieces one at a time. They don't do this maliciously, but it's a nervous habit, such as when they are talking to someone else, or talking on a cell phone, etc.

Applying the additional rubbery coating adds to the cost of the final product. In addition, there is a cost associated with peeling off the coating after assembly. Finally, even the rubbery coating won't totally eliminate the need for touch-up painting.

I am very familiar with painting processes and if you would like me to visit your facility to see what other measures can be taken, please get back to me.


Ron Joseph

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