[rodjava]

I want to make a "one of" vacuum clamp made from MDF. I don't want to use any of my HDPE material for this up coming job

I read somewhere that some type of spray or coating can be used on the MDF to make it non-porus.

It's different from simply painting both sides with latex paint.

Anybody know what I'm talking about?

Thanks in advance,
Rod
San Francisco

[Bubba]

Over on the "My newest desktop" thread, Microcarve recommends

Zinsser B-I-N Shellac White Interior and Spot Exterior Primer and Sealer

for sealing his MDF framed routers. Haven't tried it myself, but worth a shot and can be had at places like Home Depot

[zool]

Thin yellow wood glue with a little water, 3 parts glue 1 part water.

Brush on a thin coat; wipe off any runs and recoat.

If possible apply at end of the day and let it dry overnight. Do it in warm, not hot, space. No fans.

You might have to apply another coat, or as an alternative a coat of primer [not latex or water based primer].

Lightly sand with a very very fine grit or a piece of worn out sandpaper. I have heard of people using burlap.

Then paint, better several VERY light coats..mist on rather than trying to cover the MDF.

Be sure to finish both sides and pay very close attention to where the sides and top/bottom meet. Maybe even round them over so there are no sharp edges.

[vrf]

I'd use an outdoor enamel like Rustoleum.

[Markwind]

Your better off to use a double sided laminated MDF, and just seal the ends the last vacuum clamp table I made took so much paint to seal it for vacuum , it was ridiculas.

[ger21]

My preference would be epoxy, and even that would require at least two coats.

[crob09]

I suggest using epoxy, just brush it on and wait for it to dry. It will not have much flex but it will add strenght and it will make things waterproof.
Just make sure to use lots of the epoxy.

Cheers,

rob from what is a cnc

[zool]

Your better off to use a double sided laminated MDF, and just seal the ends the last vacuum clamp table I made took so much paint to seal it for vacuum , it was ridiculas.

This is an absolutely brilliant idea.

You could seal the edges with the pre-glued iron-on edge tape made especially for melamine [which is the name I know double sided laminated MDF by].

PS

If you'd like a bunch of large cut-offs of melamine .. come on over .. I got lots I have been saving .. for some reason that escapes me!!

[crob09]

you can find a contact cement that will seal it, and it comes in a can. :rainfro:
The only problem I see is it curing, it needs another face to mate with. It is a latex material.

[rodjava]

Thanks to everybody who chimed in so far. Lots of great ideas. I will give all of them a try a make a attempt to report back.

Rod

[wcarrothers1]

I coat mine with Polyurathane but that is more to give it some abrasion protection then anything else. Probably end up coating 4-5 times but it soakes in big time.

I also don't really do vacume hold downs so not sure if it makes it non porus enough.

b.

[CarveOne]

I brush on two coats of polyurethane, letting each coat dry overnight. Then the spray polyurethane will not soak in so much. It takes 5 to 6 coats of spray to equal 3 coats of polyurethane from the brush-on cans, which is less expensive.

CarveOne

[Benonymous]

Yeah, MDF is like a sponge. I've had good results with epoxy laminating resin (west system) You can brush it on , squeegee or use cotton waste/cloth as long as its clean. A couple of coats with a sand inbetween seems to work well. I roll the edges with a convex cutter on the router table. The top and bottom of MDF is much more compressed than the core and that makes the edge brittle if it's just a 90deg cut.