# Painting MDF... Please critique my materials



## krazy (Apr 6, 2009)

Alright. I'm ready to build my MDF coffee table! After a not-so-quick trip to the hardware store I came back with:

3/4"/19mm MDF boards
Kilz Original (Interior Oil-Based)
Zinsser B-I-N Primer
Rust-Oleum Flat Black Oil-Based Paint
Zinsser Shellac!

100, 220, 320 sandpaper

So... did I pickup a good arsenal for painting MDF?

My goal is to do a high-gloss MDF finish not unlike this (though that probably was covered in glass). And, for the recorc, I want to sand/smooth/spackle over where the boards of the table meet so it looks like one smooth cube.

So... in what order do I need to apply this stuff to get a high-gloss finish? Do I need to pick up anything else?

Could anyone give me a simple rundown of what I have to do and what order I have to apply/sand stuff?

I would be very grateful. :icon_smile:

Thanks all! :thumbsup:


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## bradleywellsoff (Nov 27, 2008)

On the edges, I mix water in with some Elmer's wood filler. (the kind in the white tub with a orange lid) Just enough to make it paint-able. Paint the edges with the mixture and let it dry completely. Sand with 220, prime then paint. 
That MDF will soak up some paint on the edges if you don't treat them first.
Treat any edges that have been rounded over with this same process.
Make sure you reinforce the inside of the joints. MDF does not nail or screw very well. Some wood blocks glued to the inside joints will greatly strengthen everything.
Good luck, Brad


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## krazy (Apr 6, 2009)

bradleywellsoff said:


> On the edges, I mix water in with some Elmer's wood filler. (the kind in the white tub with a orange lid) Just enough to make it paint-able. Paint the edges with the mixture and let it dry completely. Sand with 220, prime then paint.


Could I just do this with all-purpose spackling paste?



> Make sure you reinforce the inside of the joints. MDF does not nail or screw very well. Some wood blocks glued to the inside joints will greatly strengthen everything.


So you mean use wood glue and glue blocks inside the joints? Won't the MDF absorb the glue and then expand? I was planning on simply doing a screwed butt joint with 4 or 5 screws. This wouldn't be sufficient?

I'm very worried about stability because I am placing a 100lb piece of glass on top of my 19mm MDF screwed butt jointed table.


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## Gene Howe (Feb 28, 2009)

krazy said:


> Could I just do this with all-purpose spackling paste?
> 
> 
> So you mean use wood glue and glue blocks inside the joints? Won't the MDF absorb the glue and then expand? I was planning on simply doing a screwed butt joint with 4 or 5 screws. This wouldn't be sufficient?
> ...


I'm not Bradly but, I'll give my opinion:laughing:
The paste will NOT be as strong and will chip when something knoks against it. You can strengthen the paste by adding glue to it but, why not just do it as Brad suggests?

MDF edges to be glued need a slight application of glue first. Just a tad...enough to cover the entire edge to mitigate the porosity of the MDF, work it in with your finger and let it dry. 5 min. is plenty of dry time...so, that tells you that the amount of glue is scant. Then, apply the glue fully and clamp it. Then, add the blocks as Brad said. You WILL need them for stability in the use you are suggesting. I'd brad nail the blocks to hold them in place while the glue sets.


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## Rick Mosher (Feb 26, 2009)

Are you going to be spraying? It will be difficult to get a high-gloss finish like in the picture without spraying. Not impossible but difficult. For furniture with high gloss finishes these days most finishers use a polyester primer like featherfil or MLC clawlock. These are catalyzed coatings and can fill the edges and any texture with just one coat. They can only be applied by spraying in a proper booth however. If you are going the brush route the BIN shellac primer will work but I think I would start off with a good quality gesso from the art store. Several coats brushed or rolled out with a foam brush and then block sanded with 220 grit will give you a very good, flat surface with no defects which is very important before you even start with any topcoat paint.


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## rrbrown (Feb 15, 2009)

Pay close attention to even the smallest imperfection while preparing to finish and when you are actually finishing. Gloss any color but especially black will show everything. I also noticed you have Kilz Original (Interior Oil-Based) and Zinsser B-I-N Primer. I believe you only need one and would probably use the Zinsser.


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## bradleywellsoff (Nov 27, 2008)

krazy said:


> Could I just do this with all-purpose spackling paste?
> So you mean use wood glue and glue blocks inside the joints? Won't the MDF absorb the glue and then expand? I was planning on simply doing a screwed butt joint with 4 or 5 screws. This wouldn't be sufficient?
> 
> 
> ...


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## krazy (Apr 6, 2009)

I picked up some Elmer's Wood Glue and will be sealing the edges with that. Once I apply/sand/reapply/resand, do I need to apply Kilz to seal/prime, too?

As far as the paint goes, I got matte black paint and was planning on brushing it on (figuring that aerosol cans would give an uneven finish). I understand it is matte but I figured putting Shellac over it would turn it glossy. No?

Thanks so much for the wood block/glue reinforcement suggestions. I will be applying these. It would be a shame if my months of hard work for a school project go up (or down) in pieces by collapsing with 2.5' sq piece of glass on it! :huh::laughing:

BUT... is it certain a big hunk of Liquid Nails on the inside wouldn't cause bulging in the MDF? Esp since it may come in slight contact with corners?


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## bradleywellsoff (Nov 27, 2008)

krazy said:


> BUT... is it certain a big hunk of Liquid Nails on the inside wouldn't cause bulging in the MDF? Esp since it may come in slight contact with corners?


 
MDF only swells up like that if it's in soaking conditions. You will be ok with what you are doing. If you have any doubts, do a test piece on a piece of scrap

We would like to see photos of the finished product:yes:


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## krazy (Apr 6, 2009)

bradleywellsoff said:


> MDF only swells up like that if it's in soaking conditions. You will be ok with what you are doing. If you have any doubts, do a test piece on a piece of scrap
> 
> We would like to see photos of the finished product:yes:


You got it! Expect them in 3-4 weeks.


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