MDF finishing -- absolute best method

[jmar]

I'm ready to finish some MDF cabinets and have sealed all of the porous places, (edges etc) with joint compund and sanded well.

Just to confirm what I've read --

Best to use a shellac based primer and sand between coats?

Then to topcoat, either an automotive lacquer or a urethane based paint?


I've read some folks actually use a roller (which seems like a very bad idea) -- I have a complete spray shop with HVLP gun, which I imagine is the way to go.

I've painted a lot of materials but never MDF.

[jzagaja]

This is how proper gluing looks like - you have to use V bit between plates to minimize grounding. For sealing use automotive ground or better polyurethane for MDF e.g. Relidur. Acrylics enamels and 2k paints are much easier than 2k polyurethanes that can be more expensive if you use them outdoor like for yachts. Conventional spraying is preferred because of orange peel. Automotive paints and effect are well known but you have more choices like soft-coatings. I like Nextel Suede Coating from Mankiewicz.

[richie00boy]

The main issue with MDF joints showing is due to the glue you used to build the box. Rubbery glues like PVA allow the joint to move a tiny bit which shows through the paint.

I'm not sure what you mean by joint compound, maybe it's a US term for something I would normally know?

Yes a sanding sealer then normal primer, or just straight to high build primer would be a good first layer. Keep putting it on and sanding until the edge parts of the MDF are totally indistinguishable. After that you can topcoat however you wish really.

[smokinghot]

Originally Posted by jzagaja

This is how proper gluing looks like - you have to use V bit between plates to minimize grounding.

This is the first time i've seen this method, (that doesn't necessarily mean all that much). What's this "grounding" you're trying to avoid???

I would think using filler to smooth over your grooves would
be far worse than having the plates completely butt up. yes/no?

[jzagaja]

I don't know proper English terms however if you don't V shape your joints then polyester putty will sat down. Putty with aluminum is always desirable. Spray automotive primer or MDF primer unless substrate is stable. I will show you the final Nextel finish of above chipboard within few hours.

[jmar]

you said "mdf primer" -- is there a specific product just for it?

or just use a shellac based primer? (Bin?)

[jzagaja]

Shellac is always risky because of wax. Yes there ale plenty of MDF primers just ask wood industry paint dealers. I have Mankiewicz Relidur but in above we used simple automotive primer (several layers) then Nextel primer and Nextel topcoat that looks extremely smooth and high tech - used in luxury Volkswagen cars for example.

[richie00boy]

I share your concerns over the grooves and filler, that's 3 different surfaces across a joint, and 2 joint edges. Asking for trouble.

[jzagaja]

Here you are Nextel Terracota.

[richie00boy]

I can clearly see the edge of your board on that. Maybe it's the light making it look worse.

The suede style finish is nice.