[alt227]

Mineral oil is the usual substance used, as its clear and non smelling.

[indigo945]

Mineral oil is what people use these days, but it is much less funny. In practice, any oil will do, although olive oil is not suggested - smells nice at first, but will break down over time.

[geokon]

Are pretty much all surface mounted components fine with this?

I wanted to waterproof a micro devboard by submerging it in mineral oil. I was worried the board may delaminate or components would turn to goop