[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.

[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.

[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

[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.

[sploo]

I have tried water/glue, but found the sides of the MDF showed through after painting (it takes a few weeks).

Also, anything water based does tend to make the MDF move a little.

Once I can get hold of some epoxy, I intend to try various combinations of it, 2 pack primer, and an MDF primer I've picked up. It could be a while, but I do plan to post the results when I'm done.

[martinw]

I have tried water/glue, but found the sides of the MDF showed through after painting (it takes a few weeks).

Also, anything water based does tend to make the MDF move a little.

Once I can get hold of some epoxy, I intend to try various combinations of it, 2 pack primer, and an MDF primer I've picked up. It could be a while, but I do plan to post the results when I'm done.

Dear sploo,

I'm sorry you had no luck with water/glue.

Here is a link which gives a lot of information from lots of people about how to prime MDF. As you will see, opinions vary!

http://www.woodweb.com/knowledge_bas...nel_Doors.html

One more thing. I personally have never had any luck at all using water based primer on mdf.

Best wishes

Martin