Sealing MDF Edges

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Forum topic by JDL posted 02-19-2009 04:18 AM 32057 views 4 times favorited 23 replies Add to Favorites Watch
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15 posts in 3737 days

02-19-2009 04:18 AM

Topic tags/keywords: seal mdf edge corner engineered

Having built a few items from MDF, I have yet to find a suitable sealant for the edges of panels. It seems like I always have some amount of grain that shows through into my finished product. I would be very interested to hear your creative ways of sealing these edges and the effectiveness of the techniques you have experimented with.

-- Jay

23 replies so far

View Sean's profile


156 posts in 3816 days

#1 posted 02-19-2009 04:24 AM

drywall compound. its messy but it works. make it a little watery, slather it on with a finger, let it dry, buff it smooth. got it from FWW, i dont remember which issue.

-- "Democracy is by far the worst system of government. Except all the others that have been tried." ~ Winston Churchill

View builtinabarn's profile


98 posts in 3585 days

#2 posted 02-19-2009 04:33 AM

I thin some solvent base or water base wood filler and spackle it on all the edges (very time consuming). You don’t have to put it on thick, just enough to fill. Or I use a thickened type of sealer ( something compatible with your top coat paint). Once both methods are dry (using either-or), sand smooth and paint(seal) the entire surface. Let dry, sand, and refill any areas that need it again. Now move to the first top coat. Check for imperfections, fill and sand, then apply finale top coat. I use Lacquer, and I use this method on high gloss finishes. Of coarse there is wet sanding and buffing in that process also. Painting MDF to a flawless finish takes time and patience and a lot of filler or numerous base coats and sanding. Good luck. Bob

-- Built in a Barn Bob

View Sean's profile


156 posts in 3816 days

#3 posted 02-19-2009 05:11 AM

to be honest, it wasnt worth the hassle for me….i did the trim in my kitchen like that, and then swore i’d stay away from mdf and just use poplar from now on, to hell with the cost. thats just me tho. i love to cut, love to install…hate hate HATE to finish.

-- "Democracy is by far the worst system of government. Except all the others that have been tried." ~ Winston Churchill

View dennis mitchell's profile

dennis mitchell

3994 posts in 4515 days

#4 posted 02-19-2009 06:25 AM

I have not had that problem at all with MDF. Could be that my projects are finished with conversion varnish or lacquer and not paint.

View childress's profile


841 posts in 3742 days

#5 posted 02-19-2009 06:34 AM

I second what sean said. 5 minute hotmud is what I use and it works pretty good

-- Childress Woodworks

View GFYS's profile


711 posts in 3671 days

#6 posted 02-19-2009 07:27 AM

A painter I know showed me how to seal the edges of plywood and mdf with latex painters caulk if you are painting it.

View sIKE's profile


1271 posts in 3954 days

#7 posted 02-19-2009 07:40 AM

Have you tried using glue sizing? Basically watered down glue. Sand your edges really well, put the sizing on and let it dry then lightly sand and add another coat and let dry and sand again. You should now be ready to finish.

I sealed the MDF on the project below using this process and it is 90% MDF.

Click for details

-- //FC - Round Rock, TX - "Experience is what you get just after you need it"

View GFYS's profile


711 posts in 3671 days

#8 posted 02-19-2009 09:12 AM

cool shelf

View Miki's profile


56 posts in 3808 days

#9 posted 02-19-2009 09:29 AM

yes, maybe painting is good , (this is not in line of my business , i just work at plywood manufacture in china)

-- Everything is possible!

View Pie's profile


187 posts in 3606 days

#10 posted 02-19-2009 02:58 PM

I read in one of my wood rags that this guy uses water putty (same as plumbers putty?)to seal it but he was gonna spray paint his project so not sure if that will work for you.

-- Pie

View Greg Wurst's profile

Greg Wurst

795 posts in 4033 days

#11 posted 02-19-2009 06:11 PM

I’ve used the drywall mud method. Definitely works but as stated very messy. Next time I’ll try the glue sizing method using watered-down yellow glue.

-- You're a unique and special person, just like everyone else.

View John Gray's profile

John Gray

2370 posts in 4086 days

#12 posted 02-19-2009 06:49 PM

This is what I’ve used, you can mix as little or as much as you want, Durham’s Putty, this is what we used in woodshop at school.

-- Only the Shadow knows....................

View Gene Howe's profile

Gene Howe

11064 posts in 3629 days

#13 posted 02-22-2009 06:27 PM

Durham’s Rock Hard. Great stuff. Works well to seal MDF edges.
Spackle, right out of the can, is faster for edges, IMO.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View CharlesNeil's profile


2457 posts in 4071 days

#14 posted 02-22-2009 08:42 PM

there are several sealants made…but the best i have ever found is using BIN primer sealer…it is a white shellac base, several coats and give it a good scuff sand with some 320 and you are good to go…works well…as well shellac in about a 3 lb cut does well…

View jcame's profile


72 posts in 3777 days

#15 posted 02-23-2009 01:50 AM

SHELLAC is awesome for sealing mdf and easy to apply. I have used all kinds of fillers and muds and pastes and other junk I had heard of but shellac is hands down the best solution. In fact I’m about to use it on some cabinet doors I’m building for a client. GOOD LUCK!!!!!

-- Jed,Ala,

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