Tru-Oil, thinned Shellac,,any of the so called wiping varnishes (take your pick,,,tung oil, teak, danish, ect) They are just thinned out varnishes that all work about the same.
You're just looking for some protection so you don't have to continuously rub over the surface to keep it clean.
TruOil is a varnish too (oil,resin,thinner),,just linseed oil based and not quite as thinned out as most of the DIY store refinishing products.
They'll all brighten up the colors too,,same effect as wiping a stock blank with water or alcohol before taking pictures of it,,except the brightness is permanent. At least as permanent as is the coating. When it starts to wear, which it will with use,,simply recoat.
But case colors will wear with use,,they are just not very durable.
Orange shellac works nice as it's tone can 'improve' the look of the colors in many instances. But it doesn't wear as well as the others. It does come off easily though if you do want to remove and recoat.. Careful around the wood finish itself as some of the older guns are nothing but (orange) shellac finishes.
