How to Quickly Seal MDF Edges

  • Advertise with us

« back to Finishing forum

Forum topic by AM420 posted 07-16-2019 05:12 PM 418 views 0 times favorited 9 replies Add to Favorites Watch
View AM420's profile


226 posts in 831 days

07-16-2019 05:12 PM

I’m working on updating my kitchen cabinets and need to cut some cover panels to fit. Since cutting the cover panels will expose the MDF under the thermofoil, I want to reseal the MDF to avoid moisture getting in, even though I’ll take care to not have any exposed ends where water might get to them.

I’ve read some tips, but mostly they seem to take a lot of time with multiple coats of something and drying. It seems like glue-sizing is a preferred method, but I’ve never really heard of it before. Maybe just some flat white paint since my cabinets are white, but I don’t want to get any on the thermofoil that will be visible. Any tips would be appreciated.

Also, curious to hear from people how much of a gap they’re willing to fill with caulk rather than scribing and cutting to fit uneven walls. I have some gaps up to 1/8’ or more. I’ve not had much luck scribing in the past, and hope to get away with caulking instead.


9 replies so far

View Underdog's profile


1375 posts in 2483 days

#1 posted 07-16-2019 05:53 PM

Edgebanding works the best. It comes primed, and then you can use a spray-on contact adhesive.

As for scribing, I always used a 1/4” scribe mold. But where I work now, they just scribe the stiles to the wall.

-- Jim, Georgia, USA

View Fred Hargis's profile

Fred Hargis

5634 posts in 2940 days

#2 posted 07-16-2019 06:43 PM

I’ve caulked gaps that wide on baseboard trim where it didn’t follow the wall. Then painted the caulk with the baseboard and I thought it looked great. But that’s just me. If those ends on the MDF won’t be exposed almost anything like paint and/or primer, or the glue size, will do. Actually, I’m not sure I’d do anything since you said they won’t be exposed to moisture. But the glue size, or some Zinnser BIN primer (shellac based) will dry fairly quick if you’re in a hurry.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Bill_Steele's profile


536 posts in 2179 days

#3 posted 07-16-2019 07:43 PM

Maybe Bondo or Ready Patch and an oil primer?

View LesB's profile


2151 posts in 3890 days

#4 posted 07-16-2019 07:59 PM

Shellac is quick drying (as little as 20 minutes between coats @ 70 degrees) so you could put on multiple coats in a short time. Two coats should give you an adequate seal agains ambient moisture.

For glue seizing I would use Tightbond III and dilute it about 50% with water. Two applications should do it and dry fairly quickly.

-- Les B, Oregon

View Sark's profile


154 posts in 808 days

#5 posted 07-16-2019 08:33 PM

1/8” gap is fine for calking. Probably fill up to a 1/4” gap before it start looking bad. For larger gap, use of scribe molding is a good idea, especially if you have a headless pin nailer to set it in. Or you can glue it on with super-glue that’s formulated for woodworking (a thick formula) and accelerator. I’ve puts tons of molding on with superglue.

Anyway, scribe molding is very fast and easy to work with and just bends easily to hide the gaps. Scribe molding comes in 3/16” thick, and that’s better looking imho than 1/4” stuff. For the finish touch, calk the open spacing that the scribe molding didn’t get and you have a professional look.

As far as resealing cut edges, just about any white paint will work. If painting, I’d recommend an oil based primer, available at Home Depot. It covers great. The shellac based primer is too thin, so would need multiple coats, I suspect. Sand slightly to smooth out and then topcoat with some paint. Try to match the gloss and color of the cabinet doors and I don’t think that anyone will notice. I personally would pass on glue sizing, and just use the oil base primer.

View Rich's profile


4677 posts in 1037 days

#6 posted 07-16-2019 09:05 PM

+1 for scribe molding instead of caulk. It’s easy to make yourself. Take a couple inch wide board that’s 3/4” thick and appropriate length. Do a 1/4” round over along one edge, and then rip off that edge to form a 1/4” thick by 3/4” wide piece of molding. Attach it flat to the side of the cabinet along the wall with the rounded over edge facing out. It will hide any irregularities between the cabinet and the wall.

-- My grandfather always said that when one door closes, another one opens. He was a wonderful man, but a lousy cabinet maker

View therealSteveN's profile


3353 posts in 1021 days

#7 posted 07-17-2019 05:27 AM

Something like this is a lot faster, and it’s a maybe thing water will get where you are talking about, at least I think so based on your words. If it’s an absolute thing then MDO is a better choice than MDF..

If it's dry then this will get it done

-- Think safe, be safe

View Robert's profile (online now)


3468 posts in 1928 days

#8 posted 07-17-2019 02:23 PM

Drywall compound, shellac based primer, shellac.

-- Everything is a prototype thats why its one of a kind!!

View tywalt's profile


61 posts in 611 days

#9 posted 07-17-2019 08:10 PM

As others have said, shellac works well and dries quick. As for caulking vs. scribing… Am I the only one who will admit to having caulked 1/8” or wider gaps in the past? I mean it isn’t the way I want to do it… but it will definitely work in a pinch. If you stick some kind of scrap/shim in there to eat up most of the space, it will be much easier to fill. All that being said, scribing to fit is the proper way to do it.

-- Tyler - Central TX

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics