sealing mdf?

aerosol

Whats the best thing if any to seal mdf prior to painting? I've sealed it before using a rustins sealer before painting.Also painted without a sealer and apart from a shocking finish:eek: due to my lack of painting skills I can't see a difference between sealing or not......

cork1

i found that i got a fairly good result just sanding, priming, re-sanding, re-priming and then undercoating and finishing with gloss.

aerosol

Thanks cork1, what were you priming with?

cork1

it was a primer made by crown. ill see if we have any left in the workshop if we do ill post the exact name. we used it on mdf panels on the machined edges because they were a different texture to the factory finish.

ennisa

what about sealing with a coat of watered down PVA? same as is used for plastered walls. I gaurantee it will be cheaper that buying a tin of sealer I think they use a 9:1 water to PVA ratio. Maybe try it on a test panel and see what happens. Also it's not like the glue is going to go to waste if it doesn't work out. My only concern now that I think of it is how MDF reacts to water. I would try a higher ratio of PVA to water to be sure first and make sure you test it on some scrap.


Take care.

jack of all

I've used a PVA and water solution to great effect on MDF edges, routed and planed edges. It did tend to "raise the grain" somewhat, leavy the edges a little "hairy" but a little light sanding followed by a further coat left a great surface for painting. Thinned down polyurethane varnish also does a great job and dries pretty quickly if thinned adequately.

galwayrush

There is a product available at most hardwares that sell lacquers. Simply called High build edge sealer, or sometimes High build sealer. High build base coat is excellent as well.
It's usually available in 5 L tins, but i have seen 1 and 2 1\2 L cans as well.