Framing a large edition print

[Paolo]

Hello, I’m looking for some advice on framing a very large signed edition. The print is 1588mm x 1167mm (approx 66in x 46in). It is of some value but not insane (c.$1500), so professional framing, given the size, could cost almost as much as the print (UK costs are high), therefore I’d like to try to do this myself. I am a competent maker and have framed a few things but not at this scale. The advice I need really is around recommended thicknesses of materials as a factor of weight vs stability vs cost.
So, I’m thinking; pre-cut / mitred aluminium profiled frame, 4 or 5mm acrylic glass with 6mm spacers (bonded to back face acrylic).
Then; hinge mount the print with archival tape to 5mm foamex as the backboard with no backing paper. I assume direct to foamex is okay? I would like good longevity and don’t want to use mdf etc.
The print has enough of a border that I would let this over (under?) lap the frame rebate for a seamless finish (no surround). The hinge mount should be invisible as it will be concealed by the upper rebate. I was thinking to fold this back over the foamex and tape this to the back face.
For the acrylic I’d prefer to use 4mm if possible for cost and weight, for the foamex, do you think 5mm is sufficient to remain flat / rigid? Next size up is 10mm, which I’ll struggle to find a profile to fit, plus cost uplift will be a factor. I have read to use 10mm for this size of print, but given the sandwich construction within a profiled frame I am hoping this will keep the whole thing flat and rigid.
Is there any value in cross bracing the frame? Is this a done thing and are there standard products to do this?
Any other advice is warmly welcome.
Apologies for the lengthy post.
Paolo

 

[Prospero]

This is a method I use when faced with a huge piece of paper. I've used it often for poster that can not be drymounted.

Forget the conventional card window mat. Instead use a slip. The trick is to raise the back of the slip slightly so as not
to restrict the edges of the paper. I use narrow strip of Linen tape which is just thick enough.
The paper is hinged to the backing board with no more hinges than necessary.

This diagram will illustrate it....

As for the frame, I would use a wood one with a quite deep rabbet. Strength is import for something of this scale
so I would set the whole thing on a subframe which the hangings can be attached to.

Here's one I did....

Using two layers of thin wood (this is actually some cheapo t&g pine cladding) and forming
half-lap joints rather than miters makes it incredibly strong but still relatively light in weight.

This takes all the stress away from the outer frame which only serves to hold the 'sandwich' together.

 

[Paolo]

Thanks Prospero, yes I can see a lot of logic in taking the load away from the ‘decorative’ frame, so to speak. Presumably then I could use a more conventional thickness back board as this is supported by the sub frame somewhat, but might be sensible to stick with 4mm Perspex as this might still sag if too thin? Anyways, lots to think about. I’m struggling to find decent mount board at this size with paying an arm and a leg but I guess this is the territory I’m in! Appreciate the advice.

 

[wpfay]

Hi Paolo, and welcome to the G.

That's quite an undertaking.
1: I am not familiar with FoamX so I don't know if it's an appropriate archival mount board. For the best preservation a non-donor board, preferably 100% cotton rag or secondarily Alpha-Cellulose, is reccommended along with a secondary rigid support board.
2: Capturing the edge of a floated piece will eventually lead to cockling of the paper, unless you can do it in such a way that the paper can expand and contract naturally with environmental changes.
3. With acrylic, our options are 3, 4.5, and 6 mm. For that size i would probably use the 4.5 as the 3 would most likely bow. Acrylic is going to flex inward and outward with environmental changes, as it isn't a true vapor barrier like glass is.
4. Cross bracing the frame depends on the strength of the frame itself, and should be engineered into the design rather then added as an afterthought. A lot of the streeses on the frame will be a result of how you end up hanging it on the wall. Getting the weight distributed as far out on the vertical members of the frame as possible is the key to stability.
Not mentioned is the width of the rebate. Acrylic has a much higher expansion/contraction ratio to environmental changes (both temperature and humidity) and wider rebates are usually suggested for pieces of this scale. Normally ~6mm wide should be more like 8 or 9mm.

Good luck with your project.

 

[alacrity8]

One step that inexperienced framers seem to skip is to make the frame a bit larger than the glazing (glass/acrylic) size.
For items up to about 40"x32" (1016mmx813mm) that extra size (called an allowance) should be 1/8" (3mm).
For larger items, it is often a good idea to increase that allowance, especially if you are increasing the rebate/rabbet.
I have seen way to many tutorial videos, made by non-framers, that seem to think that an extremely snug fit is the proper method.

Another possible rigid backerboard that you could use is ACM or aluminum composite material.