All Replies on Sealing MDF Edges

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View JDL's profile

Sealing MDF Edges

by JDL
posted 02-19-2009 04:18 AM

23 replies so far

View Sean's profile


156 posts in 3578 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 3348 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 3578 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 4277 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 3505 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 3434 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 3717 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 3434 days

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

cool shelf

View Miki's profile


56 posts in 3571 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 3368 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

794 posts in 3795 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 3848 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

10343 posts in 3391 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


2385 posts in 3833 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 3540 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,

View cabinetmaster's profile


10874 posts in 3521 days

#16 posted 02-23-2009 02:26 AM

OK, I have to offer another solution. We do a lot of MDF doors and drawer fronts that we process on the CNC to look like paneled doors. These are always used on painted cabinets. We sand the MDF down with 150 grit sandpaper and then use 400 grit Abranet on all edges and front and back. Our finishing department then sprays them with a sanding sealer. The mdf is then sanded again with 220 grit sandpaper and a primer put on. Then a coat of paint and a coat of lacquer. We almost never have a problem with the edges after this process. I have seen doors that are over 5 years old and the edges still look good.
Hope this helps.

-- Jerry--A man can never have enough tools or clamps

View TomK 's profile


504 posts in 3837 days

#17 posted 02-23-2009 03:27 AM

sIKE – I made the same shelf for my nephew. He loves it. I used glue sizing too and a couple coats of bright spray enamel. Seemed to work well, not too gritty after sanding before the first coat of paint.

-- If you think healthcare is expensive now, wait until it's free! PJ O'Rourke

View j7langfitt's profile


2 posts in 3573 days

#18 posted 02-23-2009 04:50 AM

boy am i coming into this late. But it was on the front page so I’ll toss my two cents in. Best thing is auto body compound called Icing. The stuff is great. Its just like drywall compound but you add an activator to a little bit of it then spread it on. Benefit is it drys in 15 minutes. Sand. Paint. Done. I get a 3in diameter 10 inch long tube of it for 15 bucks. More expensive but much nicer since you don’t have to wait as long nor make as big a mess.

-- Jerry Langfitt, Canton, OH

View pauldeo's profile


18 posts in 3289 days

#19 posted 05-04-2009 03:38 AM

I just recently completed an MDF shelving system for a client. I applied a wood stabilzer/hardner made for rotted wood repairs. It sealed well, sanded good and did in fact harden the edges to help reduce chipping and dings. Finished with SW White Opex lacquer with no problems.

View a1Jim's profile


117061 posts in 3540 days

#20 posted 05-04-2009 04:05 AM

Glue sizing light sanding then thiner water base wood filler light sanding then touch up and paint.

-- wood crafting & woodworking classes

View woody123's profile


53 posts in 3269 days

#21 posted 05-11-2009 03:16 PM

I have used watered down wood glue on the edges of MDF and I also seal my board ends with this solution to prevent checking.

View kimball's profile


323 posts in 3260 days

#22 posted 05-28-2009 06:01 PM

BONDO! A trhin coat of bondo, well sanded will do the trick. A 1” stripe of hardener to a golf ball size glob of putty is about the right proportion.
Good luck Kimball

View RandyRuth's profile


1 post in 1863 days

#23 posted 03-17-2013 08:35 PM

I used 2 coats 50/50 wood glue and water. It worked.

-- Randy-I cannot get the same measurement twice!

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