Thread: Is MDF a variable density product

Yes the outer surface layer is denser.
You want put it through a thicknesser you had better

As rod said. It is available in 5mm thick, so glueing two layers together to get 10mm would be easier and better.

Cheers Andrew

If one has many projects that may use a lot, talk to TimberWood.

They make up panels of all kinds.

Taking a piece of 9mm and adding an essentially boring veneer to one or two sides to get the 10/11mm you want is exactly what they do.

MDF can't be treated as "wood"... not easily anyway... and running it through the thicknesser will leave you in tears.


I've used them for years and absolutely love them. They are the bees knees. The blokes on the ground and office are as straight forward and helpful as you'd want.

What exactly does it do to the thicknesser - does it clog them up perhaps ?

I used to work in a patternshop that only used mdf for its patterns, until I started coughing blood. Mdf was put through the thicknesser all the time no problem, except it was hard on the blades.

Arron, what's your secret project?

Artful, not so sure coughing blood is too good....

Originally Posted by artful bodger

I used to work in a patternshop that only used mdf for its patterns, until I started coughing blood.

The glue or bonding agents in MDF is really nasty.

Mdf was put through the thicknesser all the time no problem, except it was hard on the blades.

MDF is really hard on all blades and blunts them quickly - thicknesser, jointer, saws, router, molder, chisels, etc. - whether powered or hand tool.

Originally Posted by GraemeCook

MDF is really hard on all blades and blunts them quickly - thicknesser, jointer, saws, router, molder, chisels, etc. - whether powered or hand tool.

It is my understanding that most employers who care about the people who work for them are VERY careful about mdf dust these days.
In my personal opinion it might as well be treated the same manner as asbestos, cyanide, novichock etc
Still buy the stuff, usually in 3mm sheets as it is good for marking out jobs.

I used to operate an industrial CNC router in a cabinet shop. This machine used a vacuum bed to secure the sheets being processed, and initially 16mm MDF sheets were used as a combined spoil board and vacuum diffuser. When a fresh sheet of raw MDF was loaded to become the spoil board/diffuser, the machine ran a program to skim a 0.5mm layer off the top skin of the sheet, eliminating the sealed hard skin on that side. If the surface produced was clean enough, the sheet would be flipped over and a similar process run on the other side. The program could be repeated for either side if there were depressions in the finished surface, or places where the hard impervious skin remained.

Cutting and drilling bit depth was then set to cut 0.1 to 0.2mm into the spoil board to ensure that the compression bits cut cleanly through the melamine surfaces on the sheet, rather than leaving the lower melamine layer not fully penetrated and cut and hence prone to chipping the face of the sheet when separating parts. Once the spoil board surface is sufficiently damaged by this penetration, it is skimmed again (about 0.3mm) to recreate a smooth face.

With both skins skimmed of the material tends to have a fluffy surface that has extremely poor compression strength, and placing anything with a moderate surface load on the spoil board would make an impression in it. For example, dropping an air nozzle from a few inches, or even leaving a set of hard plastic ear defenders on the board over lunch would leave a distinct impression in the spoilboard. The boards also went from having the rigidity of normal MDF to that of corrugated cardboard once the skins were removed.

Based on above I would suggest following one of the procedures suggested above to build up to your required thickness, rather than running through a thicknesser to reduce thicker material to the required thickness.

Further to this re variable density of muck (MDF).
I turned a large (1200mm) disc which was glued up from multiple layers of 32 mm muck with Urea.
There was a definite hard area on the glue joins, made for interesting turning.
I was doing this in a mates workshop and he had a Racal Airstream powered respirator.
I can’t remember if I used his but I did buy one shortly after.
All the streams of shaving were put in paper bags and fed into the pot belly stove which sat in the middle of the workshop.You had to get it in quick and close the door as it was instantaneous combustion. The stove would vibrate around a bit.
Don called it ‘woof wood’.
H.