Original EM coatings were a linseed base product which is why it yellows over time. A good readil;y available solution is to use a polyurathane. I find that 80% gloss and 20% satin give a very good replica. Use a surface prep solution first like Penetrol.. it makes it adhere properly
That's what Gav taught me and it works perfectly.
EMs had a varnish which was very thin. Games were only designed to last 5 years or less before being retired. The fact they lasted 40 years is incredible.
