Mounting large poster

[Dean Casson]

Hello all,

I have a large poster to frame 900x1400 and have advised my customer we should go for 3mm plexi. The poster is a picture of a seaview out of a window, so she wantsthe finished article to look like a window frame with the edge of the moulding cropped upto the image without a mountboard. I've steered her onto a chunky moulding with a 10mm rebate.

I am slightly nervous of the possibility that the plexi will flex and pop out of the frame but think it'll be ok as I am planning on building a wood subframe faced with 10mm foamcore and some o/size mountboard as backing board. This will hopefully give plenty of rigidity and strength. As for weight and hanging i've recommended z bars or hanging straps.

My question is - as i'm cropping right upto the image edge what would be the best way to mount the poster to the board and space the artwork away from the plexi. The poster is in good condition and lies flat so I don't want to glue it, there isapprox 70mm of image free paper at the poster edges all round. I have thought of econonspacers but they recommend a max length of 600mm?

Thanks for your thoughts....

Cheers

Dean




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[prospero]

The only problem with close framing like this is that restricting the edges will not allow expansion of the paper. So if it moves with changes in moisture content it will go wavy. If you use a slip as a spacer it will not only create clearance for the glazing but you can insert a little shim so that the poster will not be crimped.

I'll try and explain....

If you use say a 20mm wide flat slip you can cut it so it encroaches maybe 6mm into the poster. That leaves 14mm elbow room. Cut a strip of thinnish board - 2ply 'barrier' board would do it. as long As it's thicker than the poster. About 6mm wide will do it. Stick these strips along the outside of the bottom of the slip. Then all you need do is hinge the poster at the top, lay the slips on top (might be easier if you joined them). So when it's all assembled the poster will not be restricted and have 8mm expansion room all round.
With a bit of luck the poster should keep flat, although a lot depends on the paper and where the framed piece is situated. It helps if the thing is laying dead flat when you frame it. If it's rolled, try and keep it flat and let it relax for a while for a while before framing it. That's if you can find a horizontal area big enough.....

Most available slips are gold/silver, so as they will be visible this may not fit in with your design. But you can get bare wood ones that you can paint. A simple square piece of timber might do the job.

I'll just add that when you get to jobs of this scale it's important to not underestimate the work involved and unless you have a giant workshop they cause a lot of general disruption. Also they are very thirsty on materials. So don't be afraid to charge.

Good Luck.

[Dean Casson]

Excellent, thanks so much for taking the time to explain it so well. I was starting to scratch my head a bit! I have some 17mm in stock which I reckon I can distress and paint to like v.similar to the moulding. might be a bit tight but will hopefully get away with it.

As for costs I have priced it at 400 Euro which is probably a bit on the light side but its in with 3 other jobs from the same customer so the total order is worth it.

Final question, am I right that plexi is the way to go?...it seems a divisive subject. I'm surprised there isn't a rule/guide somewhere - perhaps there is, I just haven't found it??

Thanks again

Dean

[prospero]

As far as plexi goes there are pros and cons. 3mm plexi will bow. At that size you really want 6mm which which means there isn't a lot of weight advantage. Also considerably more expensive than glass. I would be quite comfortable using 2mm glass at that size as long as the frame is sturdy enough. If using glass it's worth checking the inside of the rebate for any lumps that may create stress points. Also make sure the glass has no chips along the edge. I scarcely need to add that the frame should be perfectly flat. Glass will bend to conform to any twists in the frame but it means it's under constant stress - virtually just waiting to crack.

Unless you go for the specialist acrylic glazing that is more resistant to scratching, std perspex will soon get hazy if people dust it too often and too vigorously.