MDF/composite moulding for steam / bathroom mirror

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BeckyMarsha

Grumbler in Training
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Feb 27, 2026
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Florida
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Signature Art Gallery
Dear Framers:

What do we think about- or do for- a composite material moulding (see photo) for a bathroom mirror with lots of steam?

Is it a non issue, or possible to improve with paint etc?

Thanks in advance.
 

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Wood composite materials such as MDF will absorb airborne moisture like a sponge, and will eventually deform and disintegrate. If you could completely seal all surfaces (not likely), maybe that would slow the deterioration, but if you consider the added cost of materials and labor to do that, you may find that a good wood moulding would be a suitable alternative.

A poly moulding would be ideal for the wet location, if you can find one your customer likes.
 
I second Jim. We saw a ton of frames delaminate under those conditions, The wrap comes loose from the moulding and the moulding gets mushy.
 
Looks from the photo of the sample like the customer wants a mirror-on mirror effect. That might be hard to find on a solid substrate, unless there is a highly-polished metal frame available that I'm not aware of. It might have to be custom-made by a company like SmallCorp.
:cool: Rick
 
Definitely, if it is a typically small bathroom with lots of steam I would suggest a bevelled mirror with a vinyl back and sealed edges. I had one like that in my first house and it lasted all of the 35 years I lived there with no edge creep or dulling.

As has already been said any MDF type material will disintegrate pretty quickly in a steamy bathoom and even timber frames would probably suffer, particuarly if there is any gesso involved. Aluminium or poly would possibly work but having the lower edge of the glass sitting in a permanent puddle on the lower rail would probably cause problems too.

In my present home we have round mirrors in a silver frame and they are doing well so far but the bathroom is huge and the shower is well ventilated so steam is not an issue.
 
I created 2 oval mirror frames for our second bath using ultralight MDF and Red Oak veneer. They have been up about 6 years and the bath is used almost every night for showers. All surfaces were treated with a urethane and to date I have seen absolutely zero degredation. Disclosure - to whatever extent is matters, we do live in a somewhat dry climate.
 
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