What is MDF sealer?

[The Paulinator]

All these years, whenever I have finished an enclosure, sanded it, and painted it, I've just assumed there was nothing I could do to keep certain parts of the wood from absorbing about the first 4 coats of paint, and therefore making the entire enclosure lok uneven. Then the other day I read somebody say something about an MDF sealer or something that preps it for being painted so it doesn't have that problem. Is this a real product, or were they just talking about a sandable, paintable wood filler, or something?

[Nuuk]

I have seen primer paints in DIY stores labelled for use on MDF. I'm not sure if these really are 'special' or different, or merely another ruse to get money out of our pockets and into the till.

I would have thought that any good wood or general purpose primer would do the job.

[eStatic]

I have used oil-based primers on MDF and they work well. I use a brush so if it's priming for paint its another sanding job. I'm leery of using water based anything on MDF but I note that a lot of people here do it. So I suspect that's just my paranoia.

eStatic

[Timn8ter]

Automotive primer should work.

[audioaction]

I use car primer and the results are always good.

[RobWells]

I used 'mdf primer' for one of my projects, and it was like white emulsion (water based paint) mixed with 'unibond' (pva sealent - used in plastering etc)

If I want to seal mdf again I'll just mix water based wood glue 50/50 with water, and roller on with a sponge roller.

Cheers

rob

[usekgb]

Wouldn't sanding sealer work OK for this? It is often used on hardwood floors before staining, but it should work to seal MDF. I found a can of it at The Home Depot.

Cheers,
Zach

[avatar307]

What about Kilz primer? http://www.kilz.com/

It an oil-based paint that is designed for use in applications where you need to cover something up. I.e. If you want to paint a black wall white, you could paint it with Kilz (which is white) and then paint it with a top coat.

1 gallon of the Original formula is $10 at Lowes. http://www.lowes.com/lkn?action=prod...00807-153-4833

-MC

[mwmkravchenko]

The purpose of this stuff is to fill in the " end grain " on the MDF. A couple of things do work well. If you are painting then zinser primer works well. Some car primers work especially well if they are two part. If you have a lot of problems I sugest using zinser primer and then fill any blemishes with a water based putty. Sand this smooth and prime again. Sand it once more. Clean it off with a rag that is either a tack cloth or slightly dampened with water. Look closly at your finishing job at an oblique angle. Face the music and give it another primer coat. Then with a block and some fine wet and dry paper, some slighly soapy water and a lot of elbow grease sand your surfaces really smooth allways using the soapy water in a squirt bottle to lubricate the work. This method works exceedingly well and you finnishes will be at the pro level if you have acess to spray equipment.

Hope it helps!

Mark

[catapult]

Try PVA primer. It's used to prime drywall before the finish latex paint. It seals up the paper (absorbant like MDF) and plaster so the finish paint adheres evenly to the whole works without soaking in.