Old PCB lacquer gone milky white

[MWP]

Hi all,

I have a few PCBs i made almost 20yrs ago that had a coat of that Jaycar "protective circuit board lacquer" spray on them.
They were looking pretty nasty with dust, grime, etc, so i threw them in the ultrasonic cleaner (mentholated spirits as the cleaning liquid) for a few mins.
After doing so I gave them a bake at ~70degC for 30mins to make sure all the alcohol was evaporated away.

Ive been left with PCBs that are now a milky white colour, and slightly chalky in texture.

I havent tried powering up the boards as yet, but i assume the colour of the lacquer wont effect the circuits.
It would be nice to have them back to looking like new though.

Any ideas on how to clean this up?

Thanks in advance!

[aqibi2000]

Sounds very much like having a sheet of transparent perspect and then melting the surface with a splash of acetone and then expecting it to maintain the transparent surface finish