UV resistant lacquer

[Radio Fixer]

Anyone used one that they would recommend please ?

Had some cream knobs made by Wim, friend of Ben's, which were excellent but over the years the modern plastic has darkened.  Hoping that I can sand down and then lacquer.

thanks Gary

[Mike Watterson]

The darkening is sometimes flame retardant chemical migrating to the surface. Might be bromine based, so a suitable chemical might clear it. If it's the retardant then sanding and lacquer may not stop it going dark again.

[Radio Fixer]

Thanks Mike: what chemical should  try please?

As you can see he made a beautiful job of the knobs. Guess the radio

   
   

Gary

[Mike Watterson]

Maybe this?
https://thebrickblogger.com/2020/06/rest...go-bricks/

Particularly grey and white Lego used to go yellow or brownish. Apparently they changed the material and now they don't discolour.

Some plastics may yellow due to UV degrading the structure, rather than flame retardants. In such cases only an opaque paint will stop future yellowing and  any kind of bleaching might not work.

Some kinds of yellowing may respond to baking soda, or even some sorts of toothpaste (not gels, and Pearl Drops is so abrasive it's really a scratch remover).a

[Mike Watterson]

I might be wrong about bromine based flame retardants
See https://polymer-additives.specialchem.co...of-plastic

[PerdioPal]

Try some "oxy" clothes cleaner.