How stable is MDF?

[MikeG.]

I am about to replace my airing cupboard doors for the third time!

These are a pair of doors, each probably 20" x 6'-6". Each previous set of wooden doors has warped irretrievably due to the heat from the hot water cylinder and the damp from from clothes drying.

Much as I hate the stuff, I am considering using MDF this time to make a pair of panelled doors. So, I need to know that they will be stable.

What knowest thou?

Mike

 

[crazylilting]

I hate mdf! but i've seen waterproof mdf on this forum. I'd imagine it would be quite stable. We have louvered doors on ours and they haven't warped at all. Louvered doors are quite ugly to though. I've never seen airing cupboards till moving to the UK and find them a funny idea. But it is nice having toasty cloths to put on in the morning.

 

[matt]

I made some panelled doors out of MDF by sticking strips on to an MDF sheet. I used normal Medite (I think that's the brand) MDF (i.e. not the moisture resistant stuff) and they've been fine. They've not been subject to the conditions you've described but I reckon you'd be fine, particularly if you used moisture resistant.

Why not leave a board inside the cupboard for a bit to see how it behaves?

 

[Mr Ed]

Mike

Have you been in some sort of transmogrification experiment with Brad, along the lines of the film The Fly, because first he starts buying hand tools, now you're using MDF. I am highly suspicious...

Ed

 

[BradNaylor]

:lol:

Even more spooky, I am also planning on making new doors for my airing cupboard shortly...


...in oak!


True to form though, I will be cheating by applying strips of oak onto sheets of 12mm veneered MDF to give the look of panelled doors. Normal framed doors would almost certainly twist under such extreme conditions; the trouble is there is just no way of knowing in advance how the wood will behave.

MDF is very stable and ideal for the job.

Brad

 

[Tierney]

I've always understood that warping is caused by differential moisture content (or internal stresses being released, i.e. after resawing boards). Similarly I understand that normal MDF doesn't have any significant moisture, or absorb any so shouldn't expand/contract/warp.

My softwood airing cupboard door has bowed significantly; I since learned that they should have three hinges to counteract this.

In another room the softwood door sticks one half of the year and doesn't close the other half; yet I've had no problems with MDF wardrobe doors in the same room that are a similar size to yours and only have a 1 mil gap all around. They are panelled with 18mm mdf for the rails and stiles and a 9 mm mdf for the panel. They are attached with three butt hinges (screwed into the 'end grain') on each door and have had no problems with that hanging method.

I've also made a number of radiator cabinets with no problems although they're likely to have similar moisture content either side.

I thought the moisture resistant stuff was just for really wet areas like bathrooms where there is a risk of soaking in as opposed to just absorbing from the atmosphere.

As I write this, I think I'm beginning to question my logic; but, practical experience justifies my view!

DT
p.s. I think it was medite brand that I used

 

[Tierney]

oh, another thing my airing cupboard door bows outward; which, implies that there is a lower moisture content inside the airing cupboard; but, our clothes are generally pretty dry when we put them in. Trying to work out this logic is starting to make my head hurt!

 

[big soft moose]

oh, another thing my airing cupboard door bows outward; which, implies that there is a lower moisture content inside the airing cupboard; but, our clothes are generally pretty dry when we put them in. Trying to work out this logic is starting to make my head hurt!

the hotter the air the less moisture it will hold - the air inside the hot airing cupboard is warmer than that ouside - simples

 

[Ironballs]

I think you'll be fine Mike, you can do lot to MDF and it will stay straight

 

[MikeG.]

Thank you chaps......much appreciated. Quite revealing too!

Now, I've got to find a Builder's Merchants that doesn't recognise me, so that my hard-won reputation isn't shattered

Mike

 

[WellsWood]

the hotter the air the less moisture it will hold - the air inside the hot airing cupboard is warmer than that ouside - simples

Err.... t'other way round actually. I'm pretty sure warm air can hold more moisture than cold, which is why condensation problems are prevalent in winter not summer (and how the cooling of warm moist air causes rain).

 

[WellsWood]

Thank you chaps......much appreciated. Quite revealing too!

Now, I've got to find a Builder's Merchants that doesn't recognise me, so that my hard-won reputation isn't shattered

Mike

Easy, just get Brad to go for you :wink:

 

[chippy1970]

I hate mdf! but i've seen waterproof mdf on this forum. I'd imagine it would be quite stable. We have louvered doors on ours and they haven't warped at all. Louvered doors are quite ugly to though. I've never seen airing cupboards till moving to the UK and find them a funny idea. But it is nice having toasty cloths to put on in the morning.

I cannot understand people who say they hate MDF why ? is it a snobbery thing or are you just worried about safety issues.

MDF does a job and does it well if used for the correct purpose.

Yes it does work ok on airing cupboard doors mine are 18 mm and have been up for about 7 years now with no warping whatsoever.

 

[matt]

I understand the "Hate MDF" thing (i.e. I know what is meant when someone says that).

I think MDF is one of those love/hate things. It's horrible to work with from a dust point of view. Not particularly satisfying to work with. But you're sucked in by the capability of MDF.

 

[jasonB]

I've made plenty of panelled doors from MR MDF including airing cupboards, fronts for dishwashers and washing machines, bathroom cabinets, etc and not had problems with movement.

Standard MDF is more likely to swell than MR and even this will swell by about 50% if you get it really wet but just high humidity will be OK for the MR. Just make sure you treat each sid ethe same, ie don't paint the fronts and leave the backs bare.

Jason

 

[head clansman]

hi

several things spring to mind here airing cupboards in nearly all modern home seem to be an after thought (ah well we better squeeze that into that corner if it we can ) , nearly all are far to small and the poor plumber has nightmares fitting the tank let alone the the tank lagging and maybe you can just about close the door if your lucky.

Doors depending on what type you using, plywood/hardboard , or real timber , mdf is a made made product and i can't see any problem using it , whereas timber is a living breathing material with a moisture contents , warping can depend on two things really as already mentioned temperature inside cupboard and usually temperature outside cupboard plus if real wood is used moisture contents of timber when fitted , mass produced doors in timber are not necessarily at the correct moisture level.

IMHO I think when doors start to warp it usually the size of airing cupboard or, door is to close to heat source.

depending on your life style if you required lot of wet clothes dried urgently then the temperature is going to be required is hotter than most would require normally. this only leave size of airing cupboard can it be enlarged or redesigned to move door further away from heat source. hc

 

[OPJ]

Mike, I have one thing to add, which may or not apply... If you're intending to mould the MDF in some way (raised and fielded panels?) then I'd recommend you go for MR MDF, which leaves a much cleaner finish and edge than the cheaper, fluffy stuff.

Then again, if you're only after a flat, basic panel, this will not apply! :roll:

 

[RobertMP]

Funny this thread coming up now.... just as I am thinking about making new doors for the bathroom airing cupboard - in MR MDF

Oh and a matching bath panel too.

Nice to know it will all stay flat. The existing bought softwood panel doors are more twisted than bowed.

 

[MikeG.]

Martin (HC),

I'm not sure what you are getting at.

My airing cupboard is large, we don't dry much clothing in there, and because of a well insulated cylinder the internal temperature is probably well below average. The size and location of the doors is set, unchangeable. This is best-case-scenario for a modern airing cupbord door situation, and yet they still warped.

So, I simply need a pair of doors to fit the hole which will remain stable. I have made the previous 2 sets of doors in solid timber, carefully acclimatising the wood by stacking it as close to the cupboard as I could......and both pairs warped. With pairs of doors (meeting stiles), it doesn't take much movement before they look ridiculous.

So, I am going to have a crack at MDF. At the moment I can't even think how I am going to clean up a sawn edge in the stuff. I can't imagine taking a plane to it, and am reluctant to put it over the P/T. Ho hum....

Mike

 

[OPJ]

At the moment I can't even think how I am going to clean up a sawn edge in the stuff. I can't imagine taking a plane to it, and am reluctant to put it over the P/T. Ho hum....

Mike

Mike, the router is your friend! That's how I've started cleaning up timber panels as well. For what it's worth, you can plane MDF edges but, your iron needs to be sharp and you'll be back to the stone with every few passes... :S You could reserve the part of your planer nearest the rear of your machine for planing manufactured boards. Even then, if you don't get pressure in all the right places, it is dead-easy to plane a larger sheet out of square and parallel.