Mirror frame construction

[obraiche]

I am planning to make a couple of large mirror frames. I have made some in the past but was unhappy about a couple of things. I would be very grateful if anyone would share their own ideas or experience. Especialy anyone with knowlage of traditional methods and materials.

I like to use bevelled glass. On my previous frame I think I rebated the mirror to deep into the fram and lost at least 1/4 of the expensive beveling. I wonder what the recomended rebate of a mirror frame should be?

Not only does the rebate hide the beveling, it also shows as an ugly reflection of unfinished wood. Would finnishing the rebate help or perhaps matt black it?

I previously rebated the mirror to be flush to the back of the frame and just screwed on a thin mdf back panel, unrebated to the frame. Has anyone any advice on more traditional methods.

Should there be any packing between the back of the mirror and the backboard?

I better stop their.

Any thoughts or suggestions welcome.

 

[deserter]

When we make frames at work we normally only rebate 5mm into the tame for the glass to fit into but then do a deeper rebate say 10 - 15 mm for the backing, we don't put any packing between the two but as I said the backing is larger than the glass. We always fit or have fitted plastic safety backing onto the mirror so if the mirror ever breaks it stays together this is absolutely necessary on larger mirrors.

 

[condeesteso]

The double rebate above is very good - on big ones if you aren't careful the actual glass can end up becoming structural (load bearing) unintentionally! The oversize back helps stiffen everything up when you come to hanging too.
Re internal edge reflection, I make the mirror rebate as shallow as I dare go (aiming for as little as 3mm all round maybe), sometimes adjusting frame components to actual glass. I just checked on a very old gilded mirror we have here: shallow rebate (width of return) , no fancy internal finishing. I think that was traditional practice.

 

[jasonB]

I also use the double rebate method so the backing can be screwed on and stops the long edges flexing.

If you are loosing too much bevel get it cut wider say 25mm bevel instead of 20mm. Apply same finish to inside of rebate as outside of frame.

 

[AndyT]

Old books that I have read do mention blackening the inside of the rebate to avoid reflections. A quick and easy way could be to use a good permanent marker.

 

[obraiche]

Thanks for all your thoughts.

I will go for a rebated back and reduce the mirror rebate to minimum. I will also do a couple of tests with offcuts to decide on staining the rebate or not. I like the idea of finnishing to match the face. The reflection should blend in better.

That safety backing is quite expensive I believe, although one glass supplier told me that it isn't required on 6mm thick mirror glass. (!?)

How about the backing itself? I seem to remember seeing seperate thin pine panels on older frames. Even though totally out of sight I couldn't use hardboard.

I used some thin mdf just because it was hanging around last time. Any suggestions on cheep but not too tacky?

 

[condeesteso]

I agree re hardboard and it isn't structurally much good anyway. Likewise mdf which is not strong in the planar direction. Ideally I would go for 6mm faced ply, but it tends to be a bit pricey these days (birch ply seems to have almost doubled in the past 18 months for some reason). There are lower grade ply sheets around with unknown face woods and if you pick through the boards you will find an acceptable one for a lot less (timber merchants usually have 6mm etc).

 

[jasonB]

I use MR MDF to back frames, usually 6mm is sufficient even on long 8ft frames like this to stop any bowing.

Make the second rebate about 25mm wide and drill the CSK holes in the MDF 15mm from the edge.

J