varnished mdf

[sbett]

Can I paint over a varnished MDF fire surround, should I sand it first??

[sirbigtom]

Dependant on the paint, you could just paint straight over it.
If you want to be sure that the paint will adhear to the surface correctly and that you will get a good finish, however, it's a very good idea to give the surface a light sanding first.

[honkytonkman]

Just a health and safety point here. If you're sanding MDF do buy a suitable face mask/filter. The particles are very fine and can cause nasty lung problems.