Ask the Expert Question-and-Answer Archive

by Ron Joseph

July, 2005

Encapsulating Lead Paint

Q. I am going to be painting a pipeline and we would like to use ppg KL4400 anodic self-priming paint as the top coat and KL6000 tri-polar ferrite primer to spot prime rusted areas after they are stripped. The pipe is over water and we would like to encapsulate the current lead paint on the pipe before recoating it with the KL4400. Any advice you have would be greatly appriciated.

A. I am not familiar with either of the two PPG paints, but would suggest that you might apply an epoxy tie coat over the existing coating. Another idea is Carboline's "Carbomastic" which is an epoxy that contains aluminum flakes and is intended to prevent bleed-through of underlying coatings. I have little doubt that it would also prevent any potential migration of lead. If you absolutely need to prevent lead migration, I suggest that you perform laboratory tests to confirm the suggested strategies. Finally, insure that all of the coatings, old and new, are compatible with each other and give you good intercoat adhesion.

Best wishes,

Ron Joseph