Why paint the inside of a MDF cabinet?

[edekoning]

I have a question about painting an MDF cabinet. Specifically if I should prime/paint the inside or not? Looking at several builds I see cabinets where only the outside is painted, or where the inside is only primed, or where the complete cabinet is primed and painted. Does MDF warp if you only paint one side, or does painting both sides give you better protection against moisture?

[TopJimmyCooks]

In this situation MDF will not warp if finished on only one side.  There's certainly no requirement to paint the inside of a cab.  It's more work but it does make it nicer and easier to clean on the inside if you ever want to do that.  If you're worried about moisture or a damp location, it will help keep things protected.