Double-Refined MDF

Double-refined MDF provides a cleaner, smoother machined edge. But there are also ways to improve the edge of standard MDF. November 5, 2007

We have recently been machining and finishing more MDF for mantels and panels and such than we have in the past. Obviously, MDF is kind of a pain in the behind to finish machined edges. There is a mini-war going on at my employer as to what to do to make things go easier. One side is putting things entirely on finishing to make it work. I'm in the other camp that wants to go to double refined MDF. In the past, the vast majority of our MDF sales were 4x8 straight onto the trucks and to the customers, not us milling it, so when it was time to order, it was basically (I'm guessing here) whatever supplier was cheapest. I'm at the bottom of the totem pole, so I don't know the price differences. I do know the guys in finishing are way happier when they get the rare chance to use it, and in the rare circumstances I get to machine it, it seems like it's way easier on tooling.

1. Is there a price difference in double refined MDF? It's quality MDF, just not double refined. I do know we're paying a little over $16 for a 49x97 sheet.

2. Does the upfront price difference justify the later labor savings?

Forum Responses
(Business and Management Forum)
From contributor G:
I've never sawn double-refined MDF, but I've heard of it. What I can say is there are simple ways to deal with the edges of MDF products. Some wood magazine just did an article on it. They recommended using joint compound on the edges before painting. I did and it works wonders. I used to size with a diluted glue, which works too, but the spackle is definitely faster. There's always more than one way to handle a problem, but this may solve it for you.

From contributor C:
Could you please explain how you use the joint compound? And what the benefits are?

From contributor G:

The joint compound is spread across the edge, sealing it, and is allowed to dry, then is sanded to provide a smooth uniform surface for the paint primer. I think it's easier to do this, because it's just one process and it's done before the paint room. Then you can treat the edges the same as the face in the paint room.

From contributor S:
We use double (or super-refined) MDF all the time. We use it when we are machining MDF raised panel doors. Plum Creek makes some and so do some of their competitors. It has a higher density and overall finishes better. The edges are also less trouble to finish. As for price, we are paying a little over $20 for a 4x8 sheet. Before the move to double-refined we would take a can of primer and hit all the machined edges before they went to the finisher.

From contributor A:
The ultra refined MDF is well worth it if you are making raised panels. Also a spot prime of BIN shellac primer is all that is necessary on the ultra refined, whereas the regular MDF is so coarse and porous that you have to start hitting it with your favorite goop (bondo, drywall compound, glue size, spackle, etc.). I like using spackle when I get stuck with a sheet of the cheap stuff.

From the original questioner:
Getting good results is not the problem we're having. It's the amount of time involved, which I'm thinking might be alleviated by use of a different MDF, which is why I'm inquiring about double refined.