MDF Question

I`m building a fitted bookcase and am considering using 18mm MDF for the frame and shelves.

As I`ve never used MDF before there`s one question......Can the cut edge be sanded into a smooth finish ( like sanded wood?) as I want it to look smart once painted ?

Reply to
Reteplav
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Yes it can, but IME MDF isn't the best material for shelves - it sags far more than planks of softwood of the same thickness (but not as much as Conti board!).

This isn't a big problem, just be aware of it and compensate by shortening your spans. For paperbacks, I wouldn't span more than

60cm with 3/4" mdf. If you need longer spans, use PSE softwood.
Reply to
Grunff

It can, but itr will need a bit of extra treatement. The 'end grain' is very wooly and absorbent.

I'd suggest using somthing like cellulose varnish to fill and harden, then sand back to smooth finish.

Reply to
The Natural Philosopher

Be aware that machining MDF produces lots of fine dust, which is known to be a carcinogen. Proper respiratory gear is an absolute must.

I was chatting to a chap over the weekend who owns a company that manufactures trade stands for the large trade shows across Europe (he happens to be a time served carpenter as well, so knows a thing or two about woodworking). His facilities have all the dust extraction equipment required to handle this material.

We discussed MDF and he advised that MDF is an illegal material in most of Europe and the USA due to the concerns about its ability to cause cancer. He knows this because when he builds trade stands for shows in Germany (amongst other places) he turns up with stands made with MDF, and German companies can't match it because they have to use non-MDF materials. Sounds ominous, and just like our crazy government to allow nasty materials to be used in the workplace and home!

PoP

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Reply to
PoP

Thanks for the advice.

I`ve already built one bookcase using Timberboard from Wickes ( ready jointed/glued strips of wood to form a 300mm plank).

This is fairly successful but very expensive. I`ve already used 11 planks of the stuff at £16.50 per plank . The original intention was to varnish it but "`er indoors" fancies painting it now in a silk finish paint ( Any recommendations on silk paint??) which makes me think about a cheaper alternative.

I don`t fancy the danger aspect , though, of the MDF dust as I`m actually trying to cut and assemble it in situ .

Oh well ,it looks like another few more £££s to buy some more Timberboard....unless anyone can suggest otherwise.

I remember reading an old 1950s Woodworker Annual that belong to my late father and they were using hardboard on a 2" x 1" frame !!....I don`t think I`ll botherwith that idea

Ret!

Reply to
Reteplav

If you're going to paint it then plywood is a possible alternative. It's probably as strong as Timberboard (even a bit stronger maybe), but you have to take a bit more care finishing edges etc.

Reply to
usenet

"PoP" wrote | We discussed MDF and he advised that MDF is an illegal material in | most of Europe and the USA due to the concerns about its ability to | cause cancer... Sounds ominous, and just like our crazy government | to allow nasty materials to be used in the workplace and home!

But if they banned MDF the BBC TV licence fee would have to increase ...

Owain

Reply to
Owain

Yes.

You can route it too if you want an effect.

Rick

Reply to
Rick Dipper

depends on the grade of the MDF, the shit stuff the sheds sell is wooly (or was last time i checked ages ago). I believe one of the really bad ones is sourced form india and is orangeish ? The really good grades are not at all wooly and can get a reasonably smooth finish off the bat but the end grain will need some treatment to bring it to the same quality as PAR wood.

Reply to
David Hemmings

THe glue used is either urea-formaldehyde resin or phenol formaldehyde resin

Its all about taking proper precautions, there are various factors that make the dust bad, one is the dust created is very fine that if inhaled can block alveoli, second formaldehyde can be released onto mucous membranes - this has a twofold problem, firstly formaldehyde is a known carcinogen, secondly formaldehyde could cause localised tissue necrosis. formaldehyde is also a respiritory sensitiser, so e.g. can make asthma worse

also the potential release of phenol is also not going to do you much good

WHenever i am cutting any quantity of MDF, i have good ventilation, and if indoors vacuum cleaner in addition. AS well as a nice rubber dust mask with a gas filter fitted - as it is much finer grade than the usual dust filters although they should be sufficient.

Reply to
David Hemmings

I used axcryluc primer, and farrow and ball undercoat and deaf flat oil. Very soft sheen, very lovely colors.

You can cough out the dust in a day. Its prolonged exposure that will get you dead.

All these noxous things won't kill you on a one time exposure any more than gettng sunburnt once will give you skin cancer.

Use it, its good stuff, but try and hand sand, and cut and rout outside somewhere, with a mask.

Reply to
The Natural Philosopher

All wood dust is potentially carcinogenic. The risk from MDF and MDF dust is exactly the same as for any softwood and considerably less than that for some hardwoods.

This is rubbish, an urban myth which has been doing the rounds for over a decade. All MDF sold in the UK, Germany and the rest of the EU now meets exactly the same Harmonised European Standard (prEN

13986).
Reply to
Peter Parry

Rubbish or not, what was discussed was that in Germany (and other places) it was illegal to use the material. That may have been illegal to "sell" the material - I don't know - obviously if a furniture manufacturer cannot source materials he isn't going to use it in his fabrication.

PoP

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Reply to
PoP

However, it isn't. The only limit (now an EU wide one) is on the formaldehyde emissions.

Reply to
Peter Parry

I think I'm going to step back from arguing this one any further. I wish you could argue the toss with the chap I was talking to - he did seem very certain of his facts.

PoP

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Reply to
PoP

For painted built-in furniture I have found MDF to be fine.

Couple of things to watch out for.

First, as others have said, protect yourself against the dust (this applies to any woodworking with machinery, but especially the masses of fine particles created when using MDF). Decent mask. If you can connect a vacuum to your tools for dust extraction then it makes the whole process a lot cleaner - you want a 3 micron filter (aka HEPA) for MDF dust (if you're using a Henry then you can buy a £25 Microtex add-on filter from Numatic suppliers - comes with Super Henry as standard). Wouldnt' become paranoid about it - it's not in the same "one fibre can eventually kill you" league as certain types of asbestos.

Second, beware of sag. An oft posted link but a very useful one is the sagulator....

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information about bookshelf loading on that page as well.

Third, the edges need sealing before painting. I've done a lot of built in stuff with MDF so have a tin of MDF primer knocking about, but this is expensive and I don't find it particularly pleasant to paint with and achieve good flat finish (along with other acrylic primers I've used). I have been told that shellac sanding sealer is very effective in sealing the edges prior to painting but I haven't tried this yet. If you don't seal it then it will soak up a lot of paint on the edges, which might potentially lead to swelling.

Finally, to achieve a good finish I used eggshell paint applied with a small foam gloss roller (pack of 10 in wickes about £5 I think, they fit the tremendously useful behind-the-radiator small roller handle) and then laid off with a good quality 2" paint brush. Three or four thin coats give a much better finish than one or two thick ones. Allow to dry properly between coats.

Jim Tolpin's book "built in furiture" is quite good for ideas and inspiration and some constructional detail, but it's not a step-by-step construction guide.

cheers Richard

-- Richard Sampson

email me at richard at olifant d-ot co do-t uk

Reply to
RichardS

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"Firstly, the Health and Safety Executive have been taken aback and are somewhat dismayed by the reaction to comments in some factions of the media concerning the supposed effects of working with MDF, this especially as they seem to have stemmed largely from inflammatory and ill informed remarks made by the deputy general of the entertainment union that "MDF is the asbestos of the nineties. It is carcinogenic, it causes lesions, it damages eyes, the skin, the lungs and the heart. It is vile and pernicious". An HSE spokesman said that these claims cannot be substantiated, that there is absolutely no medical research which comes to such conclusions and that there have been no cases of cancer of any type which have been attributed to exposure to or working with MDF."

"Formaldehyde is designated as a "probable carcinogen" in the USA"

"That having been noted, concentrations at or above the level of the MEL are only found in work situations where large amounts of Formaldehyde is used e.g. medical, pathology, funeral embalming, etc. It is not found in anything vaguely approaching these concentrations during the working with or use of MDF wood boards or furnishings."

"MDF has not been banned in the USA, as reported in some media reports, in fact they use more of it than we do. What is now required in one state, California, is labeling on furnishings and housing to inform that the furniture/construction contains Formaldehyde."

D
Reply to
David Hearn

However bear in mind that web report was dated as September 1997. It is entirely possible that new research has come along subsequently.

PoP

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Reply to
PoP

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> I hear you, and I'm not going to argue one way or the other.

Good point, I missed that. :)

D
Reply to
David Hearn

Thought the problem was in the 'glue'?

Reply to
Dave Plowman

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