MDF

[Gary Puckett]

I just did a job in MDF (not my first choise) but the client wanted to hold the cost down.

Just would like some input for the future. How are you finishing the edges when you rout a profile on it? I sanded and sanded and when I painted it, it still came out a little fuzzy. Anybody have any tricks on this problem? Using oil primer and paint (Sherwhin W.)

Also used light weight MDF anybody ever use this material, and doo you have any comments?

Gary

[Forrest Chapman]

Gary,

You will kill yourself trying to get that product smooth. You need to start with a good "door grade" mdf. Most companies refer to it as High IB (internal bond) or Double refined mdf. After machining you can do glue sizing by mixing wood glue 50% with water and brushing or spraying on. After you sand this it is smooth and sealed. If you want to start with primer then use a good catalized primer and sand smooth. This seals the surface to where oil or water based paints do not raise the grain.

Hope this helps,
Forrest

[FredHirsch]

Garry,
We cut and paint a lot of MDF. I second what Forest states about quality of mdf. One of the things we learned is when you sand raw mdf, you want to "polishing" it, & not sand.. Use higher grit paper such as 300 + . Also, we have tried all the different primers and the most cost effective is the SW Millwork Primer. Water based and behaves like drywall paste (wear a mask when sanding). ML Campbell Clawlock is also very good but kind of costly. We don't do Kitchens, but have switched all our paint over from ML Magnamax to the ML Polystar (water).
Fred

[Jason Susnjara]

Gary,

Also Valspar has a wood filler that is sprayed on machined areas. Let it dry and then sand it. Repeat and continue with your normal process.

Mohawk has a Vinyl Primer that is either in black or white with low or high vocs depending on where you shop is at.

[Gary Puckett]

Has anybody tried Kilz Original. Just a thought, Using semi gloss oil paint

Gary

[Will Williamson]

A Catalized primer works the best on cut edged. Contrary to reccommended procedure I don't even bother to sand at all until I have applied a good heavy Coat to all machined areas .You can either spray it or brush it .It dries in just a few minutes. I only have experience with Sherwin Williams Kemvar or Ml Campbell Clawlock What ever product you use make sure it has high solids content. The first time you sand the edges use 120 grit open cut sand paper I use Klingspore brand Do not put that same heavy coat on the whole piece just narrow down the spray gun and do the edged first. Usually two coats and you have a smooth finish ready fo top coat.

[Rob Perry]

We do lots of MDF & we use Becker Acroma Bernyl Surfacer for the primer coats x2 & Becker matador top coats x2. Also we use the highly refined MDF.
We take out Saw or routermarks out with a 80 grit Block, hit it quickly with a Medium 3M sanding sponge & start spraying.
Sand smooth after first coat of surfacer with a used 3M sanding sponge. Sand between other coats with a fine sanding sponge.
The edges come out as good as the face.

[Al dedenus]

We do a lot of MDF as well.lite board although easier to handle hasn't got the same density as one with a high I.B.We give a quick sand with 120 grit then move to 180 grit and finish with 320 grit.All done with a dynabride dual action sander with 3M stick-itsThe trick is to get your job to the paint shop as quick as possible as humidity effects the raw material.When our polish shop gets backed up we resort to glue sizing but normally just straight to the paint bay with no problems at all(with the exception of moulded edges which we always glue size 50/50 glue -water sprayed on