I was looking for some wood board for a project recently and MDF was an option. But gone are the days where I think “yep, that will do the job” and I just buy it – I decided to look into MDF’s environmental street cred.
What is Medium Density Fibreboard?
Medium-density fibreboard (MDF) is a wood panel product made up of wood fibers (rather than small chips used in particle board) that have been bound together by heat, pressure and resin binders.
The wood fiber used often comes from pine plantations, but just about any wood waste can be used in its manufacture, including paper.
Advantages of MDF
– Strong – nearly double the strength of particle board
– Denser than plywood
– Can be painted
– Can be drilled, screwed (using suitable fasteners) and easily sawn
– Much cheaper than “natural” wood
– A good insulator
– Sound-proofing attributes
– Fungus/mold resistant
– Flammable, but difficult to ignite
– Can be recycled
All this makes medium-density fiberboard sound like a dream product, but there is one major environmental issue – the binders.
MDF and formaldehyde
Like particle board and some plywood, the binders and resins used in MDF may contain formaldehyde; a known carcinogen. While I found some references stating lignin can be used as a binder (a naturally occurring substance found in plants), it still seems urea- formaldehyde based products rule the roost.
One of the big problems with formaldehyde is it’s a substance that keeps on giving. Products containing formaldehyde will continue to off-gas for years. It’s for this reason plus the fact MDF is also susceptible to moisture that it’s recommended medium-density fibreboard should be sealed with paint.
Painting MDF doesn’t solve the problem though – it just locks it away.
While MDF can be recycled, the processes for doing so are relatively new and recycling drop-off locations seem to be few and far between. The UK appears to be the leader in MDF recycling at this point in time.
Landfill is still the most common final resting place for MDF; where chemicals will leach out over time, possibly contaminating groundwater.
Other toxic volatile organic compounds (VOCs) may also be off-gassed for a few months after manufacture.
On the (somewhat) brighter side; it seems MDF uses less in the way of binders than particle board.
As the levels of formaldehyde based binders will also vary between brands and grade, asking about off-gassing/binder and other potential environmental contaminants while at your local hardware store may be worthwhile. Two types of formaldehyde-free MDF I was able to find available in the USA are Medex and Medite II.
Just to clarify, by “formaldehyde-free”, I mean in reference to binding agents – all wood has some level of naturally-occurring formaldehyde.
For low/no-VOC Medium-density fibreboard, be prepared to pay more for it; but it should still be cheaper than “natural” wood.