MDF doors warping.

[Manks]

Hi All

We have had a joiner make some cabinets for us with MDF doors. They look great and in keeping with our house. We have painted them using Farrow and Ball paint, but the doors have started to bow a bit, i.e. 3mm.

Each door is about 4ft tall and has 2 hinges. The joiner says he can return and put in a third hinge, but I would prefer to sort the problem myself if possible.

Any tips please?

 

[biffvernon]

In keeping with your house? But surely the house isn't made of mdf? I thought it was a lovely old place.

Sorry I can't help you as I'm thinking of a joke about an Irishman and Birmingham.

 

[Penners]

I'm thinking of a joke about an Irishman and Birmingham.

Oh come on. Don't leave us hanging...

 

[Penners]

Manks - in which plane are the doors bowing?

Have you painted them identically inside and outside?

A skin of paint exerts tension on a surface, and if it's not balanced by an identical skin on the other side, warping can occur. The same effect can be caused by improperly balanced foils and veneers.

 

[Manks]

Well we have had some carpet installed too, and despite the fact that our house isn't made of axminster it seems to look OK.

No danger of a helpful response Biff?

Manks

 

[Manks]

Penners

They are bowed between the hinges, so horizontally I suppose.

No, the doors have more paint on the outer. I am sure that there is unequal tension. Also the doors have softwood mouldings on the outside, which may have some impact.

Manks

 

[biffvernon]

Oh alright then.

Lost person: "Could you tell me the way to Birmingham, please?"

Irishman (replace with whatever ethnically disadvantaged minority your personal prejudices suggest): "Well now, I wouldn't be starting from here."

 

[Manks]

I take it from your line of thinking, Biff, that you mean that asking on a period property forum is not a good place to start asking about MDF.

Well, Penners came up with a helpful comment. Furthermore, whilst I am not the world's biggest fan of MDF it certainly has its uses in any property.

Ten years ago, I suppose these cupboards might have ben made from softwood and ply. Today they are made of softwood and MDF. Had my only options been solid timber, I wouldn't have been able to afford to have these cupboards.

So, today I have some cupboards that look superb (apart from some bowing) and they are, in design, sympathetic to the property.

One cuts one's cloth according to one's means. If that means using MDF to achieve what would otherwise be unaffordable, I am all for it.

Manks

 

[biffvernon]

My kitchen has plywood cupboard doors that I got from B&Q 20 years ago. They were varnished for about 15 years, then got painted blue.

Here's a picture of a kitchen down my lane. The doors were made by my neighbour Roger. He used fiddleback sycamore inlaid with bog oak.

 

[Nemesis]

Small but possibly pertinent point - MDF isn't too good environmentally. It contains some fairly not good substances I understand.

Its manufacture provides jobs I know but this factory is a major blight on the Tyne Valley:

http://www.egger.co.uk/co-uk-eng/egger-co-uk.htm

 

[Manks]

Small but possibly pertinent point - MDF isn't too good environmentally

Not entirely relevant, but if you have any advice given where I am at right now it would be appreciated.

 

[Nemesis]

Actually, I wonder how far apart the cost of wooden and MDF kitchens are in reality? I know that there are some very upmarket ones, but there are cheaper ones too:
http://www.woodcrafters.co.uk/why.htm

Can't help - the only bit of MDF we used (bathroom) warps and then straightens up with humidity. I wonder if it's the nature of the stuff?

 

[chuckey]

Another thing that could cause this problem is unbalanced moisture content, i.e. the outside of the doors are warmer, hence dryer then the inside. I would unscrew the doors and prop them up inside the cabinet to see if they start to straighten. It could be caused by the mouldings, were they allowed to aclimatise before fixing? A third hinge would straighten out the one edge of a door but not the opening edge?
Frank

 

[Manks]

I didn't fancy kitchen units in my sitting room.

 

[Andrew Bodenham]

MDF has its uses, and Manks asked a perfectly reasonable question which demands a suitable technical answer. It irks me when forum members who have nothing useful to contribute to a topic feel they have to comment anyway.

Manks - I think Penners and Chuckey are on the right track. If the doors are on a built-in cupboard then there's a fair chance that one side will be warm & dry, whilst the other is colder and (perhaps) damper. This might add to tension effects.

Adding another hinge would be a straightforward way to tackle the symptoms, although some experimentation to determine the underlying cause would be useful. If you leave the doors open for a couple of days it would show if differing conditions inside and outside the cupboard was the cause - hopefully the doors would straigthen out.

 

[Nemesis]

MDF has its uses, and Manks asked a perfectly reasonable question which demands a suitable technical answer. It irks me when forum members who have nothing useful to contribute to a topic feel they have to comment anyway.

Well that's the nature of the forum!

And you have no control over it at all...

 

[Manks]

Thanks Andrew

I am forming the opinion that it is difference in tension on the front vs the back, probably due to the paint. On which basis, I intend to repaint the backs of the doors and possibly with the doors flat on the ground.

Manks

 

[biffvernon]

Sorry Andrew, but as you may have noticed, this is a forum where the netiquette of non hijacking threads is largely ignored. It adds amusement and sometimes throws up useful information for others.

This will also be of little use to Manks, but I think mdf has the ability to absorb a lot of water and if the doors were made or stored in a damp environment and then moved into a heated house without the opportunity to dry out evenly from both sides then warping is likely.

I used mdf as a backing for a large, metre square, photograph recently. It was a bit of a rushed job for an exhibition the next day. The mdf came out of a builders merchant's shed and was put into the frame immediately. Within a few hours the photo was badly warped - liked it had taken a bath.

 

[Manks]

Well that's the nature of the forum!

Nope, it's the nature of some of the posters here. I am pleased to report that the majority of posters here tend towards constructive advice and positivity. However, there seems to be an overwhelming temptation for some to criticise, when helpfulness is the order of the day. This is fine if the criticism is valid, but all to often it is opinion and prejudice dressed up as valid comment.

I have been using this forum since it was in the old format like a grocery list. You were then, as I recall, posting under another name (Evelyn perhaps). I also recall that you refused, point blank, to use the "new fangled forum". Yet, here you are. You do realise, I presume, that you are now using the message board equivalent of MDF?

Manks

 

[Lime]

My experience of MDF is that it has no internal structure to give support (both with rigidity and flexibility) so is reliant on density and shape.
It is absorbent of water and this produces an expansion of the material eventually resulting in it's destruction.
Moisture is a key factor as is the covering on it's skin because unequal humidity on opposite surfaces produces warping.
It is essential that the complete exterior is sealed.
I would have fitted as many hinges as reasonable possible to support it's weight and give it some reference to warp back to.

MDF may serve a purpose in isolation where it does not need to refer to another shape accurately (like a table) but a door is another matter.
It would never be my choice of material because of it's weight, lack of flexibility, vulnerability to water and physical damage.
Unfortunately because it is "sold" as being made of wood many people are beguiled into believing it is as good as wood.
It isn't.
Wood is a complex structure produced to perform a specific purpose of supporting a tree and this gives it many special properties.
MDF has none of them.
However if the grain of wood is ignored then wood will fail too.