Waterborne finish on MDF without raising the fibres?

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Forum topic by 404 - Not Found posted 12-17-2011 12:32 PM 3341 views 0 times favorited 7 replies Add to Favorites Watch
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404 - Not Found

2544 posts in 2932 days

12-17-2011 12:32 PM

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

7 replies so far

View hObOmOnk's profile


1381 posts in 4090 days

#1 posted 12-17-2011 02:00 PM

Dewaxed shellac.

-- 温故知新

View Alan Robertson's profile

Alan Robertson

66 posts in 3881 days

#2 posted 12-17-2011 02:40 PM

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

-- MrAl

View Rick's profile


9416 posts in 2995 days

#3 posted 12-20-2011 07:32 AM

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.

-- LIFE is what happens when you're planning on doing Other Things!

View Viking's profile


880 posts in 3158 days

#4 posted 12-20-2011 07:40 AM

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!

-- Rick Gustafson - Lost Creek Ranch - Colorado County, Texas

View NiteWalker's profile


2736 posts in 2539 days

#5 posted 12-20-2011 12:37 PM

+1 for dewaxed shellac. I use Zinsser SealCoat.

-- He who dies with the most tools... dies with the emptiest wallet.

View Greedo's profile


473 posts in 2923 days

#6 posted 12-20-2011 01:47 PM

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.

View 404 - Not Found's profile

404 - Not Found

2544 posts in 2932 days

#7 posted 12-20-2011 10:10 PM

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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