# Waterborne finish on MDF without raising the fibres?



## renners (Apr 9, 2010)

I don't spray a lot of mdf but when using waterborne paint, I haven't quite managed to get away from the fibres raising on the surface. I can get the finish right in the end with maybe 2/3 primers and 2/3 topcoats, flatted between coats. Has anyone found a technique to eliminate the problem of fibres raising that isn't quite so time consuming?
I always put a good coat of emulsion on the cut edges first to bind the fibres and sand back smooth which works well, it's the fibres on the surface which have always been a problem. Is there a sealer or should I use cellulose primer for the mdf?

Any advice would be appreciated


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## hObOmOnk (Feb 6, 2007)

Dewaxed shellac.


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## MrAl (Sep 3, 2007)

Agreed. I cut mine 50/50 with denate alch. 2 to 3 coats, light sand, tack. Dries very quickly.
Good luck.


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## Magnum (Feb 5, 2010)

I use this for Pine also to seal it, ONLY if a Natural Finish though, as it blocks the stain.

50/50 Methyl Hydrate and Regular White Shellac. Dries very fast, Quick "Sanding" with 000 Steel Wool, Wipe off and a Good Vaccuming to get the Steel Wool Remants is a MUST!!

If it's a "Not All That Fussy" of a Project i.e. Personal Use, I just brush on Water Based Poly, Maybe a One Hour Dry and sand it with 100 Grit, Vaccumn, Maybe Steel Wool or 150 Grit and Vaccumn again. Another Coat Of Poly, maybe two.

I'm assuming you have Stained your Project before all of the above.


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## Viking (Aug 26, 2009)

I just did a project with MDF and used KILZ water base as a primer and sprayed 2 top coats of enamal. No raised fiber issues. I also use MinWax water based Polycrylic on unprimed MDF all the time and again no issues.

Good Luck!


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## NiteWalker (May 7, 2011)

+1 for dewaxed shellac. I use Zinsser SealCoat.


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## Greedo (Apr 18, 2010)

the first coat of water based finish will always raise the grain or at least give a rough finish, i just sand after the first coat of acrylic varnish with nothing lower than 220 grit, and apply another coat. 2 coats are enough with acrylic to get a glass smooth surface if you use paint that is thich enough. Spraying it may not be the best option, i use a roller for mdf.


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## renners (Apr 9, 2010)

Interesting reading, thanks for all your input. Some of the products mentioned above are just not available in Ireland, the paint store I go to has just started stocking Zinsser stuff, so I might check that out the next time I'm painting mdf. There's nowhere in this country where you could walk in and ask for dewaxed shellac flakes, but Rustins Shellac Sanding Sealer is sold in the above mentioned paint shop and my local hardware store, so that's an option too.

Thanks again


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