[monte55]

Is there a preferred bit to cut MDF.............I wan't to cut out numbers, shapes etc.
Also, is there a good sealer to seal MDF prior to spray painting? It just sucks spray paint in. I'm thinking of a dip ................any ideas? thanks

[ger21]

If you're talking about the top edge being rough, you can use a downcut spiral. Unfortunately, downcut spirals tend to get dull rather quickly. MDF in general tends to dull tools quickly. For best results, always use very sharp tools.

[kentavv]

Also, is there a good sealer to seal MDF prior to spray painting? It just sucks spray paint in. I'm thinking of a dip ................any ideas? thanks

I have used spray-bomb enamels - those left a horrid finish on MDF - and oil based brush-on enamels - OK, still sucked the paint pretty good. If I ever paint MDF again I would be inclined to try spraying with an epoxy primer initially.

Oh, for some project I tried to seal MDF using polyurethane. That was REALLY sucked up. Sealed up really well but the finish was rough.

Hope this helped.

[Madclicker]

Seal the edges and the cuts with a mixture of 4 parts water and 1 part white or yellow glue.

[martinw]

Seal the edges and the cuts with a mixture of 4 parts water and 1 part white or yellow glue.

I use a couple of coats, and de-nib with 240 grit paper. If you use steel wool after the second coat, you can get the edges of MDF really smooth.

I use a spirit based primer.. I've never had much luck with the water solvent quick-drying stuff.

Best wishes


Martin

[turmite]

Take a few minutes and look this site over. This type finish is the best there is for mdf.

Mike

http://www.seagravecoatings.com/polyeste.htm

[routalot]

I find shellac based sanding sealer good.It may need to be thinned but one good coat,left to soak in and then when thoroughly dry,de-nibbed with 150 Fre-cut paper works well.

[ger21]

But I bet that would be some nasty stuff to apply in the garage.

[turmite]

Prolly! But I use a home made booth of sorts and it, or rather a product similar to it isn't too bad.

Mike

[sploo]

The best results I've had are with high solids 2-pack auto primer. Unfortunately, it uses an isocyanate based hardener, which is very nasty stuff.

I'm still hunting for a product that will really coat edges of MDF (so that they can be finished glass smooth) that isn't going to kill me...

[ger21]

Try finish sanding the edges, then brush on epoxy, and use an automotive spot putty to fill in any voids.

[sploo]

That might do it. Whilst I prefer spraying from the speed point of view, it's not real healthy without the right gear.

I know someone who's using epoxy paints, so I might be able to get a 'sample' for testing.

Do epoxy paints give off any dangerous fumes when painting with a brush?

[ger21]

Not paint, just regular epoxy, preferably a thin type. Use it as a sealer, then prime and paint.

[sploo]

Ah OK.

The only epoxy I usually see is in very small tubes in hardware stores (and is very expensive). I am aware you can get larger cans/drums of it, but it's not something I've ever noticed for sale. I'll have a hunt around.

[Runman]

No easy way to get a mirror finish to mdf. Hard work will prevail, lots of
sanding and filling. I use a waterbased filler, similar stuff to what you might
use when grain filling for polish.

[JerryFlyGuy]

Ah OK.

The only epoxy I usually see is in very small tubes in hardware stores (and is very expensive). I am aware you can get larger cans/drums of it, but it's not something I've ever noticed for sale. I'll have a hunt around.

Check out Westsystem.com and locate the nearest distributor. Its about as cheap an epoxy as you can buy in reasonable quantities. Works great too!

They also have a fairly informative website..

HTH

Jerry

[sploo]

Many thanks Jerry, I'm following that up right now!

[mxpro32]

Ive found the best way to get a really smooth finish on the edges of mdf is to sand it really smooth to begin with and then seal it with a water/woodglue mix as ger suggested. then a denib sanding will leave a smooth edge. paint with a sandable primer, and you can wetsand the edges super smooth.

[havalina]

MDF is easy to work with. Easy to mill, easy to paint. Its just different from reg wood.

Forst off after milling it sand it with 120 then 220 then seal with shellac or any other ast drying sealer. Then paint or sand as needed.

I hear a ton of people having a hard time with MDF but I build cabinets every single day. Its not hard to deal with at all, just different from wood.

End grain or milled areas are very porous and need to be sanded then sealed before any kind of painting is done to them. It is well worth it for the cost and also the ease of milling

[dtman2]

The dollar store here (S. Ontario - Dollarama) is now selling those two-part 5 minute epoxy syringes for a buck for 25ml. I had good luck thinning it with methyl hydrate and brushing it on - a 50-50 mix gives you a litre of sealer for 22 bucks (including the methyl hydrate) which isn't bad. Dont do a whole litre at once unless you paint really fast though - thinning it does stretch out the setting time from 5 minutes but not that much. If you get it to really soak in the MDF is more like phenolic at the end.