This is a post from the Aussie grumble I thought would be of interest. Author is Jared Davis of Hughes
To me, it sounds like you may have a “Peter Lik” limited edition photo (testing my psychic ability ) They are popular photographs in North Queensland for tourists at the moment.
ILFOCHROME CLASSICS
An Ilfochrome Classic (formerly known as Cibachrome, until Ilford bought out the process) is high quality glossy photo, which requires special handling and mounting. They are extremely expensive to print and produce, and probably more expensive if they are limited edition signed photos, like the one you have. As you can imagine, super glossy photos are also extremely unforgiving when it comes to showing imperfections or contaminates underneath their surface.
The recommended method for mounting Ilfochromes is as you have been informed. Either mount them on to aluminium sheeting or on to an ultra-smooth surface like gatorboard or kapamount.
Although it is perfectly fine to mount down normal photographs using Gudymount or Economount, or other systems, the only way to mount down an Ilfochrome is using a specialized (ultra smooth) Neschen pressure sensitive adhesive with a Neschen cold roller mounting system, on to a super smooth substrate. This is quite simple is you have the rollers and the materials, and does not require a lot of "skill".
The “mounting process” also needs to be “dust-free” to eliminate any dust or contaminates getting underneath the Ilfochrome (ie: You can't just chuck it through the rollers, which are next to your double mitre saw and an open window!)
The recommended Neschen adhesive to use for mounting Ilfochromes is Gudy 802, which is the highest quality of adhesive available for demanding work such as this.
WHY ARE ROLLERS THE BEST WAY FOR MOUNTING ILFOCHROMES?
You cannot use a cold vacuum press with spray adhesive, because sprays are too “lumpy” and do not create a smooth surface (not to mention that they are carcinogenic!)
You cannot use a cold vacuum press with wet adhesive (ie: 3475, etc), as the moisture will ruin the glossy surface, and are also “lumpy” which does not provide create a smooth surface.
You cannot use a cold vacuum press with pressure sensitive adhesive, because this does not work & I can explain this elsewhere for those interested.
It is safer to avoid heat. Mounting systems which use excess heat can ruin the super glossy finish of the Ilfochrome.
SUBSTRATES
Aluminium is dimensionally stable, inert (ie: PH Neutral) and does not corrode like other metals, so it is absolutely safe to use as a long term substrate. Aluminium is the recommended standard to use for Ilfochrome Classic photos. But obviously, being a sheet metal, it is expensive and not the easiest substrate to work with.
Gatorfoam can be used, because it is dimensionally stable, but is expensive and requires preparation – You need to “polish” the gatorboard with ultra fine sandpaper first, and then clean the surface with film cleaner or acetone before mounting. Gatorfoam only comes in a 48” x 96” sheet which makes it difficult to ship single sheets, and you need a bench saw to cut it (like MDF). Currently we only sell this product by the catron, but if there is a big enough demand for selling single sheets of Gatorfoam, would could possibly look at implementing this as an option?
Kapamount is a good option, but unfortunately we stopped selling this product about two years ago, because of the lack of demand for this type of product.
Fomecor is not smooth. When you mount a glossy image down to fomecor, you will notice what they call "an orange peel" effect which shows through the reflection.
Jetmount has a thicker surface paper than fomecor, and is a little bit smoother than fomecor, but nowhere near smooth enough to use as a substrate for an Ilfochrome.
3mm MDF (Craftwood) is dimensionally unstable, because it is hydroscopic, and does not have a smooth surface either. Not to mention it's other delightful qualities like dust, hard to cut and work with, saturated with acid, etc.
Acrylic (Perspex) is very smooth, but unsuitable to use as a substrate because it is hydroscopic. This means that over time, it will allow moisture to migrate into the adhesive, which will react and cause outgassing (ie: bubbles).
SPECIAL HANDLING
It is best not to touch the surface of an Ilfochrome, as your finger prints will become visible over time, because of the chemical reactions of the oils from your hand and the photo surface. A pair of polyester gloves would be the safest way to handle an Ilfochrome print.
… IN SUMMARY
Unless you have a pressure sensitive "cold" roller mounting system, the safest “I don’t know any other option” way to frame an Ilfochrome is to hinge it, as you have already done. However by doing this, you risk making your customer unhappy, as in your case.
If your business is not ready for rollers, it might be best to consider “outsourcing” these jobs to be professionally mounted down by a business that has rollers, knowing that everytime you do so, you are creating more business opportunity for yourself to eventually justify your own. It will not be "cheap", but then again this is not a "cheap" print. The fact that it is not "cheap", also indicates that fact that it can be profitable sideline to a picture framing business.
If you wish to contact me, I can refer you to list of possible businesses in your area who understand the fundamentals professional mounting.
My advice would be to get this done properly, or don't get it done at all (ie: leave it hinged)... but don't compromise using an inferior system of mounting, risk the chance that your customer will be even more critical of the result, and consequently unhappy.