View Full Version : MDF

09-05-2002, 10:56 PM
Medium Density Fiber. So, is there low and high density fiber board?


09-05-2002, 11:53 PM
Low density is called fibreboard - used for bulletin boards. High density is called OSB (oriented strand board).

Beams made from wood strands are Engineered Laminated beams (developed in BC) - tough stuff. Uses a Microwave cured epoxy to glue it up under high pressure.

Peter S
09-06-2002, 12:02 AM
"I was told" (so may/may not be true) that what we call hardboard in NZ (very hard, about 1/4" thick, dark, almost black) was the same stuff as the real low density fibre board (pin board stuff), just squashed flat under heat.

Hmmmmm..."squashed flat"...you can tell I've got a thorough technical knowledge of the timber industry...look, if you can't weld it, its not much good, right?

[This message has been edited by Peter S (edited 09-05-2002).]

Uncle Dunc
09-06-2002, 12:22 AM
In my experience, high density fiberboard is what Peter S. calls hardboard and what we call masonite in the US. OSB is neither high density nor fiberboard. It's about the same density as playwood, while masonite is much denser. And it is made of relatively large flakes of wood, while fiberboard is made of wood that has been processed to separate out the individual wood fibers, much the same as in paper making. Fiberboard doesn't even have to be wood. There was an outfit in South Dakota making MDF out of wheat straw.

09-06-2002, 01:13 AM
Yep, there is particle board (weak, soft, lower density, bigger particles, machines like crap, surface not great, not horrible)

MDF (stronger but somewhat brittle, small particles like dust plus a lot of glue, dense and heavy, hard, machines well, good surface)

flakeboard (stronger than particle, but still weak, made of big chips thrown in and pressed with glue, bad surface)

OSB (chips are long, oriented in two directions N-S, E-W, E-W, N-S in a typically 4 layer board. 70% of plywood at its best, machines like crap, bad surface)

Block ply (veneer over thick blocks somewhat laminated. Only as strong as the veneer layer and the glue if laminated in core)

Plywood (3, 5, and 7 ply, pretty strong, etc, you know...., but may vary as to voids etc. Mexican ply may have big voids)

Good plywood, (13 ply baltic birch, or 18 ply Russian, machines well, strongest wood product made, good surface , although russion is uneven as to thickness, and need sanded)

Fiberboard (the dark pegboard, made of stuff like paper, pressed with something like bakelite. Weak compared to other stuff, but flexible and bendable.)

09-06-2002, 09:26 AM
As far as I know there is regular MDF, I think its about 80#s per 4x8x 3/4 sheet. then there is what is called ultralite which looks the same but is 40#s per sheet. I got this from a friend who works at a cabinet shop.They quit using particle board about 4 years ago because MDF was so much easier to work with and could be painted. MDF doe'nt absorb as much moisture as particle board.

Alistair Hosie
09-06-2002, 09:44 AM
In U K there is low, medium, and high, density fibre board plus fireproof, water proof,outdoor, stuff.
When it came out here at first we were told you could rout it on the edges etc and paint it mold it everything .I have found here in u k that all the medium density stuff is pretty weak at the edges and is to put it a better way very furry to the touch it does not paint or rout as good as it used to I think we are being sold an inferior density (weaker) in order to do all the things it used to I have to get High density board from a specialist suppliers which is not cheap.Also this stuff contains fomaldehyde which is a carcinogenic so mask up well before cutting Alistair

09-07-2002, 05:52 AM

You forgot 3 & 5 ply Baltic Birch (two types stiff, or extremely bendable)

And my Fav - cement board - great for backing up sower tiles.

I forgot about masonite and the white board used for signage (high density). The white board is weather resistant even on cut edges. Neither of these bend well - they snap in two.

The OSB is used for sheathing, roofs, and what not - is very strong when nailed or screwed flat - does not bend at all.