It’s going to soak up a case of spray lacquer. I coated some mdf on a sharpening station I made four coats of urethane later it could use 5 more coats!

 

thanks what can I seal it with

 

What about painting it?

 

I might have to do that

 

"Finishes" aren't "Sealers"
Clear Shellac is a good sealer. So it thinned epoxy. CA glue, etc.

 

As you are seeing by the responses MDF is like a sponge when it comes to putting finished on it.
To late now but a melamine coated MDF would have been a good place to start if you wanted a clean surface. That said, I think I would use Shellac and if I had some that was getting old on the shelf I would use it up first. It dries fast so two coats in a couple of hours is easy. After a couple of quick coats of shellac (if it is de-waxed like Zinnser's seal coat) you can apply a couple of coats of poly for a harder more serviceable finish.

John's idea of thinned epoxy or CA would also work but could be messy and it would take a lot of CA to do the job....too costly.

I have a 3/4" top layer of MDF on my work table and I just coated it with some old water based poly I had on the shelf. I had to sand lightly after the first coat but it worked fine.

 

Yeah use the melamine coated stuff next time, but I have used sealcoat shellac successfully. Spray or brush on. Put it on in fairly lights coats and let it dry for a couple hrs. This limits the amount of absorption. You could try a waterbased finish, I just never wanted water anywhere near mdf. Try it on ancutoff piece and see what happens.

 

I've painted MDF without much issue... just rattle can spray stuff (enamel). First coat basically seals it to keep subsequent coats from soaking in. For example, here is a band saw stand top I made of MDF with three sprayed on coats:

Cheers,
Brad

 

I use a couple of coats of oil based poly and then wax it. keep it waxed and nothing will stick to it.

 

All five of my table saw sleds are made of MDF. I left them bare. If I were to give them a protective coating, I'd probably use spray paint in a color that wouldn't be a hindrance when using the sleds. Such as white. MDF covers well with spray paint.

 

Painting MDF?
When I am being lazy, and using something from big box store: I use BIN shellac based pigmented primer on MDF. Over-wise, use a generic pigmented vinyl based lacquer primer/sealer from my finish distributor. These are lot easier to sand smooth, than straight shellac. It also does not waste time/material penetrating as deep as straight shellac, thus requiring less primer. Two coats, and sand smooth; is enough to prep MDF cabinet doors for most any pigmented top coat. Can even brush on the primer, if you don't mind some extra sanding.

+1 I leave my sleds as bare wood, or cover them with melamine laminate (Formica/Wilsonart).
Painted finished tend to be soft and sticky, unless waxed regularly. Raw wood covered with hard carnauba wax works same, and requires less time to finish.
It's just a work shop jig, not something for sale or show?

 

thanks for the suggestions

 

I use the following mixture on all MDF surfaces in my shop:

Equal parts:

Boiled Linseed Oil
Naphtha
Polyurethane

If you want more finish, after it's dry you can recoat with poly.

Shellac is OK, but it's gonna soak it up like a sponge.

 

I am curious.... why the mix? What does it get you that the poly by itself doesn't? How did you come up with this mix?
Cheers

 

Just soil? No water?

Anything will work for "just sealing it."

For moisture, that would more challenging because MDF doesn't generally do well for moisture. Maybe an epoxy sealer and whatever topcoat you want.

I recently built one of these little speaker kits with my 13 year old son

that comes with all components and you assemble the cabinet (MDF) and install everything yourself.

I primed the cabinets with some primer. I was applying some 2k, single stage "jet black" automotive paint to some miscellaneous truck parts and decided to shoot them with that. I think they turned out pretty good.

 

my big issue with finishing MDF is that it is like a sponge even some sealer. I have some kiltz I may use that and paint over that although I don't want to paint it Ill have to

 

Kiltz is far too sticky for a sled. It's a latex super primer made to go over stains and everything on walls and floors. If you use it make sure it has time to dry before top coating or you'll be waiting a long time for it to dry. Kiltz is a great product for covering those mashed potato and gravy stains the kids put on your wall but it's just too much for a shop sled. The only finish that truly fills the surface and dries on top of the MDF is latex paint and maybe acrylic, so maybe you are headed in the right direction.

I still recommend oil based poly, it doesn't chip like paint it dries thoroughly in 24 hours. With a wax coat it will hold up for years. I do like the 2K auto paint that @floresc012548 used (It's dead s3xy!) but that's way overkill for a sled though.

Here's one of my many sleds finished with poly and wax:

 

Gotta agree with Arthur... poly is my go to finish for shop jigs and fixtures. Couple coats of wipe on and it's sealed for life. With the wipe-on, you can get three or four coats on in less than a couple hours, particularly on MDF.

Cheers,
Brad

 

I just use paste wax on shop jigs. It's easy to apply, renewable, and can be refinished, without stripping, with poly if needed.

 

I just use paste wax on shop jigs. It's easy to apply, renewable, and can be refinished, without stripping, with poly if needed.

Hi I made a wedgie sled out of MDF. Iwant to seal the MDF agaist soiling, can I use spray laquer to do this or would something else be better.

This has Rustoelum 2X on the MDF bought at Walmart and it didn't take any more shake rattle spray than regular wood and my daughter says it is still looking good after a few years use.
I sprayed some water base color on it before spraying it with the 2X then welded up some wrought iron for the base and shot a little flat black on it. Made me happy
I think MDF gets some uncalled for bad comments but the only thing about it is its too heavy with a lot of it in a project

 

1" thick MDF Drill press table got 2 coats of finishing wax. Low cost, simple to apply, easy to maintain, and has held up very well.

 

For any of my MDF jigs, and most jigs in general whether they're plywood, solid wood or MDF, I give them one heavy coat of regular polyurethane, wipe it completely off the surface, and then depending on whether it's supposed to be a sliding part or a sticking part, apply a coat of wax.

 

I wanted tyo use What I had so i painted it then waxed it

 

Have you considered an adhesive vinyl or similar? No challenges with soaking up sealer/finish. I've used this method with some MDF recently and am pretty happy with it.

 

I haven’t built mine yet, but I was going to try a rattle can to seal up the mdf and then was going to paint it with graphite infused paint to help it slide effortlessly…

I’ve not tried it yet so I can’t speak for the results- but that’s my plan for my jigs

 

ok thanks