MDF Sealer

[dabomb3k]

Hi guys, just had some mdf sheets cut into skirting for a room and there bare at the moment...
What's the cheapest / effective way to seal it
Before painting with a water based satin?

I've heard pva can do the job, I've also just bought a Diall primer and undercoat in one from b and q which says its for bare wood but not sure if I can put this straight onto the mdf or if I need a "sealer" first

Online I've read that a product called Rustins MDF sealer will do the job and isn't too expensive but wondering what your thoughts are on this??

Thanks in advance...

 

[Deleted member 174758]

Diall says low VoC, so I suspect that it's a water carrier. Try cheap white French polish or a thinned-down oil undercoat - all water-based primers will raise the grain of MDF quite badly IMHO. Even then you'll need to sand to 180 or better 240 grit before you start and give it 2 or 3 coats, denibbing between coats and at the end with the non-woven synthetic cloths that car sprayers use - like these. White polish is good because it goes off fast - you should be able to do 2 coats in an hour - but it needs to be warm (timber as well - cold timber will chill it and slow down the evaporation of the carrier) and it is a bit niffy because of the meths (carrier) in it