Understanding MDF

[petermillard]

Good advice above. Personally, I’d use MRMDF as the baseline - nothing to do with its moisture-resistant capabilities, it’s just a much better board than regular MDF, doesn’t cost much more, is readily available, takes paint well and is flat and stable. It cuts well, and there are lots of ways to join it back together again.

As others have said, its density means it will sag under its own weight so you need to be sensible about unsupported spans when designing, but for workpieces with a painted finish it’s hard to beat.

Manufacturers have their own naming conventions, but broadly there’s regular MDF (brown) MR MDF (green) flame retardant MDF (pink) and exterior MDF. Also from medite, Extreme MDF (Tricoya), but as I say, for most general cabinetry and painted pieces, MRMDF is the baseline, for me. Medite has a good website explaining the different types they produce. HTH P

 

[Chris70]

I’m surprised no one has yet mentioned the formaldehyde hazard when working with MDF and the need to take precautions. I’m very new to this hobby and do like MRMDF’s stability and finish, versus plywood, but a tad nervous of using it myself. Can someone soothe my paranoia? The powered respirators seem so expensive to me!

 

[Mark18PLL]

Is Kronospan a decent manufacturer?

 

[sploo]

I’m surprised no one has yet mentioned the formaldehyde hazard when working with MDF and the need to take precautions. I’m very new to this hobby and do like MRMDF’s stability and finish, versus plywood, but a tad nervous of using it myself. Can someone soothe my paranoia? The powered respirators seem so expensive to me!

At least in the UK (and rest of Europe?) MDF is now low formaldehyde. However, it's still awful stuff to cut. Believe me, a powered respirator is very cheap vs your lungs.

 

[DBT85]

I’m surprised no one has yet mentioned the formaldehyde hazard when working with MDF and the need to take precautions. I’m very new to this hobby and do like MRMDF’s stability and finish, versus plywood, but a tad nervous of using it myself. Can someone soothe my paranoia? The powered respirators seem so expensive to me!

Watch the video from peter about formaldehyde.

More is released from an orange than some mdf. Its all made to meet the legal requirements.

 

[doctor Bob]

I cut it all day long. I have good extraction, my health is fine.
I'm more worried about hardwood dust.
The only people I ever see in this industry with work related health problems are old turners.

 

[sploo]

I cut it all day long. I have good extraction, my health is fine.
I'm more worried about hardwood dust.
The only people I ever see in this industry with work related health problems are old turners.

I suspect there's a fair bit of personal variation (like the guys that smoke 20 a day and live well until they're 90+, vs the guy that smokes little and goes down with lung cancer at 50).

Having been a bit of a silly boy in my youth, and cut way too much MDF in a small garage, with little to no PPE, I'm certain I've not done my lungs any good - and it's sensitised me to the dust quite badly.

Wearing a powered respirator for a whole ~8 hour shift would not be my idea of fun, but for us "home gamers", a Trend AirShield Pro (or equivalent) is a relatively small investment vs the value of your lungs, and is perfectly fine for a few hours of cutting duties. I only wish I'd bought one ten years earlier.

 

[AJB Temple]

MDF is almost invariably in sheet form. Most of us I imagine will cut it with a track saw. Personally I don't use a lot of MDF but when I do I cut MDF without wearing a mask, but I link the tracksaw (Mafell - so there is no side port) to a good Festool vacuum and there is no discernible dust. I am asthmatic and the slightest thing sets me off. Good extraction is key.

I'm not surprised turners get issues. Your head is always close to the work and it is very hard to get really effective dust collection on a lathe in my (limited) experience.

 

[sploo]

I'm not surprised turners get issues. Your head is always close to the work and it is very hard to get really effective dust collection on a lathe in my (limited) experience.

That's why I definitely wear the air fed mask when turning. For obvious reasons, the full face protection obviously helps too!

 

[doctor Bob]

I use the air fed mask if I have to enter the works toilet after the Christmas party.

 

[sploo]

I use the air fed mask if I have to enter the works toilet after the Christmas party.

I'm not sure that only an FFP3 filter is going to cut it. Definitely you'll be needing a Type A Organic Vapour filter

 

[Spectric]

Hi

I can recall a high build brush on primer used in autobody finishing, thick pea green goop that was resin based and when rubbed down with wet glass paper produced a glass finish, so what high build primer is being used on Mdf please?

 

[Chris70]

Thanks to all, for your reassurances. Looks like I'll need to start wearing protection when I eat my jaffas!

 

[mg123]

Meyer have just responded to my quote request, they do not deal with the public and only sell to trade apparently.

Of all the different types of fibreboard MDF is used in the vast majority of furniture that is mass produced. The cheaper end of the market uses chipboard, then it is types of fibreboard and then moving up to blockboard and then plywood and then finally solid wood.

Most bespoke makers (those making fitted furniture) use mostly MRMDF (if not using decent plywood) for the things they make as it is far superior to the ordinary MDF as the resins used make it much more durable. It also has a much cleaner edge when worked, is easier to seal and the face takes a finish much more easily and cleanly (smoothly) than the cheaper stuff.

If you do use regular MDF avoid that which the big box stores sell, it is sh 1 te. Look to buy Kronospan, Medite or buy from suppliers such as Meyer. Meyer will sell direct and deliver; their site below:

https://meyertimber.com/products/commodities/mdf?view=all

 

[porker]

Hi

I can recall a high build brush on primer used in autobody finishing, thick pea green goop that was resin based and when rubbed down with wet glass paper produced a glass finish, so what high build primer is being used on Mdf please?

I just use Leyland MDF primer but have also used a 2 part polyester wood filler in the past for good results. I found it was pointless sanding the edge before applying primer, much better to sand after it has dried and repeat as the paint raises the fibres slightly then top coat.
I've seen a few projects with high gloss surfaces but never gone that far personally. On my home projects I tend to use face frames and solid wood edging often acting to thicken and strengthen shelving etc.

 

[Droogs]

@mg123 sorry about that I must have given them my HMRC UTR at some point and forgotten.

@porker & @Spectric I use Isopon or Proworx as my filler and Autopaints International for high etch and high build primers and then usually their 2 pack paint if it is a painted finish or if the customer wants something else then that. This is the finish i usually look to aim for in something glossy

 

[Droogs]

If something has a routed or moulded edge and is made from MDF, I usually run the bit to create what i want and then really press on a layer of filler and leave for 24 hours and run the router/moulder again to give the best possible edge finish that only needs a little bit of touch up sanding ad then primer

 

[DBT85]

Meyer have just responded to my quote request, they do not deal with the public and only sell to trade apparently.

If they only sell to trade but are happy to sell in small quantities then it's really rarely hard to get an account.

 

[mg123]

If they only sell to trade but are happy to sell in small quantities then it's really rarely hard to get an account.

They've provided an alternative supplier who work on their behalf so still possible but likely to be more expensive. I'll give them a call later in the week to place an order (cost dependant of course)

 

[pe2dave]

No need for edge banding, if you seal the surface sufficiently then painting will look as good on the edge as it does on the surface, I spray paint all of my MDF, high build primer and two or three coats of whatever I am using,

what is 'high build primer' please? I've not heard of it.