I don’t claim to be an expert in framing by any means, but, as an artist making a lot of original artists prints – in the form of intricately cut and engraved wooden puzzles and engravings – that, crucially, I hope, will survive in pristine condition for hundreds of years – just like my Giclée prints – I have some very demanding or exacting framing requirements. Having made a special study, there seems to be very little published literature on this subject (which is not surprising because it is quite a niche topic) – and what little I have found doesn’t completely fulfil my goals.
Before getting into what my requirements are, let me start by setting the scene. Framing is a compromise between conservation (or preservation/protection) and public display. At the extreme, one could wrap the artefact in something chemically inert and pH neutral (6.5 – 7.5) – like cotton rag or archival tissue paper – and keep it in a microbe-proof, insect-proof, light- and air-tight, container – in a temperature- and humidity-controlled environment. This is precisely how the vast majority of precious museums’ and galleries’ artefacts are kept all over the world – in storage, and out of public view (can be as much as 95% of their collection!) – the reason being that the vast majority of these heritage institutions simply do not have the space to display all their (often growing) collections.
At the other extreme, the artefact could be displayed as-is – giving the viewer a completely unhindered view – as if it were right in front of them. For example, imagine seeing and handling a precious 14th century illuminated manuscript. How long would that survive…?!
Unfortunately artefacts demonstrably deteriorate from the effects of ultraviolet (UV) radiation, airborne and material-contact acids (like the acids produced from the degrading lignin in wooden frames), temperature fluctuations, consumption and decomposition by the FBI (fungi, bacteria, and insects), water/moisture, etc. – and so valuable and/or irreplaceable items need to be protected from these harmful forces.
A balance needs to be struck between making the artefacts accessible – and this invariably means viewable by the public at close distance – and protection/conservation. Conservation is a special and vital consideration because it involves maintaining the artefacts in their current condition for as long as practically possible – and this invariably mean hundreds of years. The publicly viewable conserved artefact is invariably achieved by encasing it in a display frame – i.e. a completely fixed and controlled internal and external environment – using materials and techniques that demonstrably preserve and protect – and which have passed the test of time.
What are my special requirements of framing wooden puzzles? Well, it stems from the fact that they are not completely flat (2D) – like a lot of conventional flat art is. They are not what is conventionally considered 3D, however, they do have thickness or depth because of what they are made of – and this is conventionally called “2.5D”. And what they are made of, and how thick the material is, is relevant to their aesthetic, heritage, and value – and so I feel strongly that this should be visible in a frame. To display a wooden puzzle simply as a flat, 2D, object makes it virtually indistinguishable from a conventional print or drawing, it’s impossible to see what it’s made of – and I feel something vital is lost. If you look at my conventionally framed “Long-eared Owl with Oak Foliage (Art Puzzle)” (2023) – this is scored and cut plywood (see below),
the cut lines and score lines are intentionally indistinguishable from each other (to trick the viewer – a metaphor for camouflage) – and so one could easily mistake this for a drawing on paper – rather than something which is made of 3mm plywood and has been extremely intricately cut and scored by a very high precision laser (see below for an “exploded” view)…!
I think it’s important to see what material the puzzle is made of, and how thick it is – and this means being able to see the sides as well as the back. So this means, at the very least, there has to be unobstructed glass at the front, sides, and back…
As a frame of reference (pardon the pun!), here’s a diagrammatic cross-section of a simple frame (without a windowmount) :-
Obviously the sides and back of the puzzle cannot be seen, and the frame rebate obscures part of the front.
One option I considered is a double-sided version of the framing method called direct contact overlay (DCO) or encapsulation – which involves holding the artwork down flat with a very thin sheet of clear polyester film such as Mylar®/Milenex® or Reflex®, or extremely fine mesh fabric like nylon tulle or silk Crepeline® – stretched over a sink mat (inlay mountboard). At the very least this approach would involve a sheet of polyester film or fine mesh fabric on both front and back, with window mounts on the front and back, and it would look something like this :-
This is unsatisfactory because, firstly, neither polyester sheet nor fine mesh fabric is are strong enough to hold flat reasonably heavy loose artefacts – especially from both front and back – or for transportation (puzzle pieces could easily become dislodged with the vibrations and shocks that would inevitably occur during transportation). Secondly, the polyester’s reflectivity detracts from the overall aesthetic for the viewer. While Reflex® is the least reflective I know of, no clear sheet polyester film that I have come across comes close to the non-reflectivity of museum glass. When we consider the lengths and cost of developing non-reflective acrylic museum glass, I feel it would be a travesty to additionally layer a sheet of Mylar®/Milenex® or Reflex® in front of a valuable artwork if we don’t have to… And no fine mesh – even silk Crepeline® – is completely invisible on close inspection – and so it’s better not to use them unless there is no viable alternative.
Finally, it would be very difficult to maintain the required tautness across the full width and height of large and heavy puzzles (some of mine measure approximately 600mm by 400mm) – so some pieces could easily tilt forwards, or even become completely dislodged – and potentially get damaged – when the frame is hung. And with a sealed frame package it would be very time-consuming, and not without danger, to take apart, fix, and re-seal…
Another issue with this method is that the sides of the puzzle (or other 2.5D artefacts) cannot be seen because the sink mat and windowmount – both being made of opaque mount board – obscures a side-on view. So I looked for another solution.
So why not simply stick the puzzle between two sheets of glass – with enough gap beyond the side edges so that the sides can be seen as well – as in the diagram below…?
Some fundamental rules of conservation framing are that the artefact should be preserved as-is/intact, should not be damaged/deteriorated or altered in any way, and any glue must be non-permanent and completely (and easily) reversible. So sandwiching the artefact between two sheets of glass is fraught with all sorts of problems.
Let’s consider the impact of the glue on the wood. It would have to be a starch-based (water reversible) glue that would have to adhere to both the rear sheet of glass and the puzzle wood. Whilst starch-based glue would probably work (I have successfully done some testing), the issue of reversing it would be incredibly cumbersome; and separating all the puzzle pieces without damaging them would be a nightmare! So starch-based glue is very much not easily reversible and carries a high risk of damage when removing the puzzle from the frame. No, gluing is not a viable option.
Moreover, many framers and conservators would balk at the idea of even having glass touching the artefact! The reasons being that condensation can form on the inside of the frame and it is completely unacceptable to have moisture come into contact with artefact, mould could develop on inside of the glass and on the artefact, the artefact could stick to the glass (thereby making separation difficult and dangerous), and there could be a “ghosting” effect on the glass – which, at the very least, is an irreversible loss (transfer) of pigment from the artefact to the glass.
So if we can’t glue the puzzle to the glass, how can we fix it between two pieces of glass and show the front, sides and back…? One solution would be to snugly surround the artefact with with a sink mat (obviously it should not be a tight fit in order to allow for expansion and contraction with temperature fluctuations) with enough thickness of mountboard so that the artefact is completely held in place at all sides – and the glass sandwiches it top and bottom . Let’s called this the naïve glass sandwich solution so we can refer back to it later on. It is shown below :-
As stated from the outset, framing is a compromise between preservation/conservation and visual public display – displaying the artefact to its best advantage. A compromise I am suggesting (and do myself) is to have a glass sandwich – very much like the naïve glass sandwich – but crucially not to have full and direct contact pressure between the artefact and the glass.
In the naïve glass sandwich solution, glass would be in full and direct contact with an artefact to the extent that it would be pressing down on the whole surface of the flat object. But what if we introduced a thin shim into the sink mat of the framing package so that the glass is not pressing down on the whole surface of the artefact – instead it is pressing down on the surrounding sink mat mountboard – which has been made very slightly deeper than the artefact? This will take the full and direct pressure off the artefact – resulting in the slightest possible, non-pressured, contact – as shown below :-
Like the sink mat mountboard, the shim should also be 100% cotton card (I used 280gsm [approximately 360 microns] card – the same colour as the 3000 micron mountboard). The net effect of this shim is to give approximately 180 microns of space front and back, between the artefact and the acrylic glass. The artefact can, and will, come into contact with the acrylic, but it will not be under any pressure (pressured contact is not acceptable as previously discussed). Moreover, the artefact has ample room to expand and contract with temperate fluctuations – with no adverse effects.
If acrylic is used instead of silica-based glass, it is far less prone to condensation formation. This is due to the fact acrylic is a far better insulator (and therefore poorer conductor) than silica-based glass, will therefore not fluctuate so quickly to temperature changes, and therefore is less likely to present a cold enough surface temperature upon which moist air can reach the dew point and condense.
Moreover, if the whole frame package is sealed completely air-tight with an impervious tape (like aluminium barrier frame-sealing tape), and assuming there is only normal humidity in the artefact before sealing, the risks of internal condensation formation should be so negligible as can be discounted.
How to achieve an all-round side view? Well, since we are only dealing with relatively shallow depths (6mm in my case), bevel-cutting both of the 3000 micron (3mm) sink mat mountboards gives us a 45 degree side view from both sides of the 6000 micron thick sink mat. In fact, because the artefact in only in contact with the apex of two back-to-back bevel-cut mountboards, nothing of the artefact is hidden or obscured from view – as may hopefully be seen more clearly in the following close-up diagram :-
Are here are some example photos showing this side-viewing capability front and back :-
Should the sink mat layers be glued together – as is common practice? In this instance I think this is not necessary because the three pieces are required to be exactly the same size (are best cut with the same cut stops on the mountboard cutter [or computerised mat cutter]), they simply cannot move at all in the compressed sealed frame package, it’s extra work, and any glue is not without risk – even wheat starch or Methyl cellulose.
To allow for natural slight expansion, the size of the sink mat window should obviously be just slightly bigger than the artefact – but not so big as to allow the artefact to slosh around in the frame. I suggest about 2% larger – so about 1mm per 500mm length. And the positioning of the sink mat window relative to the sides, and whether you want symmetry or not – is down to the individual preferences of the framer or client. My preference is sideways symmetry – i.e. equal spacing at the sides – and vertical asymmetry – i.e. the old standard of 45% top and 55% bottom – to allow for natural down-shift of the whole package in the frame (due to margin allowances), and to compensate for visual perceptual effects of the frame being hung at eye-level on a wall (see below).
With this approach a rear frame/slip is required to secure the sealed frame package in the frame – pressed firmly against the front frame moulding rebate – and fixed, as normal, with stiff framer’s points. In my case I used a small plain frame moulding and routed out the rebate – making a plain rectangular profile, because the rebate was getting in the way (see below) :-
Both frame mouldings at the back of the frame can be finished off with normal water-gummed paper tape (or some other FATG Level 1 acceptable frame-sealing tape). Here is an example photo detailing this :-
Here is a complete front view of a frame following this solution (I’m in one of the shots just to give an idea of the size) :-
And here is a rear view :-
So this concludes the proposed museum (FATG Level 1) frame design for wooden puzzles and other thin, flat, 2.5D artefacts designed and intended to be viewed from both front and back. If the artwork is to be hung on a wall – and not frequently viewed from the back – then ordinary acrylic seems adequate – and will cut down on the not inconsiderable costs of this solution. The only time I feel it would be necessary to use museum acrylic glass on both sides is where the frame is to be displayed in such a way that it can always be seen from both sides – such as in a free-standing display partition, in an interior wall with an opening/hatch, or suspended from a ceiling away from a wall – where viewers can wander all around it.
Incidentally, notwithstanding the UV protection provided by the museum acrylic glass described above, I additionally varnish my wooden puzzles and engravings (front and back) with the best available UV, non-yellowing, clearest, matt varnish. The point being that, wherever possible, the artefact in the frame should be given as much non-invasive, non-destructive, protection in and of itself – a belt-and-braces approach to conservation. This is similar to using archival UV protective inks in Giclée prints – as well as UV varnishing them – and not relying solely on a museum grade (FATG Level 1) frame to protect them…
References
Kistler, V C (2001). Conservation Framing, Vol 4, 2001. Library of Professional Picture Framing.
Miller, J (2021). Direct contact overlay mounting. ART + FRAMING TODAY, April-June 2021.
Kosek, J M (2004). Conservation Mounting for Prints and Drawings. A Manual Based on Current Practice at the British Museum. Archetype Publications in association with the British Museum.