In very simplistic chemical terms the AR solvents will not bother cured/dry UR coatings. There might be a problem with adhesion plus
there would be an issue about the reliability due to the different material characteristics of the product with this sort of combination.

AR coating can be easily dissolved by many liquefied organic compounds. Thus the solvents (except water solvents and possibly UV cured solvents)
in spot applied UR materials will "attack" most  AR type finishes.

You might be required to "qualify" this process with your end users.

Good luck.

David A. Douthit
Manager
LoCan LLC

Bogert wrote:

Folks, does anyone out there have info on whether Type AR conformal coating is compatible with Type UR. I have been told that Type AR coating can be used to touch up (e.g. for cases where parts are being replaced) printed wiring assemblies that have cured Type UR coating applied but one cannot go the other way.  That is, you cannot use Type UR coatint to touch up assemblies that have cured Type AR coating applied as the UR coating will react with and dissolve the AR coating.  Is this correct?