# The quickest way to a flawless paint finish on mdf, what works for you?



## renners (Apr 9, 2010)

Let me preface this by saying I have painted acres and acres of mdf.

I used to use waterborne primer, but invariably found the waterborne formulas would raise those flecky bits more than I would like. So with a waterborne primer the workflow would go something like this:

Tack cloth -> spray a light primer coat -> spray light primer coat 2 -> light sand/tack cloth -> spray wet primer coat -> sand flat/tack cloth, notice raised flecks now exposed by sanding , -> spray another light primer coat -> sand/tack/start spraying top coat.

I got sick of this and switched to Zinsser B·I·N as a sealer and primer. This virtually eliminates the problems of raising the flecks in a sheet of mdf, two coats of B·I·N and a careful sand leave a perfectly smooth primed surface, BUT, if anything, it seems to take way longer for the top coat to dry over the B·I·N. - adding hours to the drying time.

What other ways of preparing mdf are there that won't lead to extended drying times for a topcoat?

I'd consider using cellulose primer apart from I don't know if there would be compatibility issues with a w/b top coat, and really, I see spraying cellulose primer as a step backwards.

I also know that not all mdf is created equal. I always buy a brand called Caberwood Premier which has a better surface than sheets costing a few € less. Spray equipment is Fuji HVLP.

Any insight you can give me to speed up painting process would be much appreciated.


----------



## Loren (May 30, 2008)

My pro painter friend recommended "weenie rollers" as
an alternative to spraying. She worked in a team with
her ex who had cut his teeth nitro finishing yacht interiors - 
he could make a front door look like it was dipped in
glass. She never sprayed though… too much setup
and she didn't have his touch and experience I guess - 
her specialty is murals and trompe-l'oeil.


----------



## DKV (Jul 18, 2011)

Edited


----------



## Gene01 (Jan 5, 2009)

Second Jonathon's recommendation. I use oil based color coats.


----------



## renners (Apr 9, 2010)

Thanks for the info Jonathan, I just looked up Becker Acroma's precat products (which are the only ones available here) and discovered that they are a Sherwin-Williams company, so their pre-cat system is quite possibly the same as the one in the link. This is something I will definitely be looking into in the New Year.


----------



## NiteWalker (May 7, 2011)

That's odd about the zinsser BIN primer. It's great.
I've never had trouble with top coats taking longer to dry.
Spray primer coat, light sanding with 320, spray primer coat, light sand with 320, paint coats.


----------



## renners (Apr 9, 2010)

Nitewalker, if time wasn't an issue, I'd be happy to use BIN on everything. I applied a waterbased top coat with a 2hr touch dry / 6hr recoat which was still tacky after 12hrs. It's been fairly mild here today and I had a 16" fan going and a fan heater making for good air circulation and warm. This is frustrating for me as I can't work when I've got jobs drying on the bench.


----------



## Wdwerker (Apr 14, 2012)

I use ML Campbell's Agualente waterbourne sanding sealer and finish, clear and solid color versions. A couple of coats of the sanding sealer will sand to a silky smoothness. A couple of top coats and you are done.


----------



## NiteWalker (May 7, 2011)

Try some dewaxed shellac (zinsser sealcoat). That might do the trick.

That's really odd about the topcoats taking longer to dry; I've never heard of that.


----------



## roman (Sep 28, 2007)

pre cat primer

followed by precat lacquer

even quicker, post cat primer followed by post cat lacquer, increase the % of catalyst slightly…..dries almost as fast as its applied


----------



## DLCW (Feb 18, 2011)

I just completed a project consisting of 700 letters ranging from 4" tall to 56" tall. They were cut from MDF with laminate (colored). Total project size was 35 sheets of MDF. I cut them all on a CNC machine then had to paint the edges of every letter to match the laminate color.

The way I found worked really well, for me, was to spray two coats of the paint and let it dry thoroughly. Then sand with 180 grit and then spray a final coat. The edges turned out perfect and the customer was extremely satisfied.

I used a Cricket air sprayer to apply the paint. Used water based latex thinned so it would go through the gun.


----------

