Correct me if I'm wrong, but I believe the process was fine tuned & first developed commercially by an old mate of mine. He owned the factory which used to make those fake walnut panels in 80's/90's Rover cars ! This was at least 20yrs ago in Colwick Nottingham.

I don't know much about it, they tried to keep the method secret 'cos they couldn't patent it. It might be all BS 'cos he certainly had to turn sideways to get his ego thru a door, but I do know he made £millions from it 'cos no one else could do it at the time.

It was developed from a process which used various chemicals floating on water in a tank, one of the chemicals I remember being mentioned was borax, the part was then raised from the tank & the chemicals floating on the surface would be transferred to the part. This method is as old as chemistry/alchemy itself !

Nowadays, you can buy production line machinery that will coat your parts in this way as fast as you can make them.