 The topic of today's presentation is the research project that Lee and Daphner, Chris McGlinche and I are carrying out at MoMA since last June 2015. And I'm pleased to be here, but I'm representing all of them. So rather than taking pictures or write a lot of notes, please take a picture now of this QR code. This is not a hinge or an adhesive. This is a code and if you can scan it or take note of this link, you can find this presentation online or part of it. I will present some of our findings and some of them would not be understandable online when this video of these two days symposium will be online. So this is another way to review our findings. And for us it's also a tool that I don't know will help us to receive your comments, suggestions for adhesive or if you have experience other solution for engine RC papers, all of these information will be more than welcome. The Museum of Modern Art maintains a very active exhibition program for 3 million visitors per year through an average of 50 on-site presentation, 10 to 10 traveling partnership exhibition and projects. With one gallery of 50 hundred square feet devoted exclusively to photography, there are photographs to be found in every curatorial department and are integrated into a number of exhibitions across the board. The acquisition and display of resin coated photographs and digital prints on RC type papers is now routine. Some of the oversized print can be quite large. These works as well as many contemporary photographs require delicate minimal exhibition mounting but present certain challenges. Conservators hinge RC papers relying on available adhesives on their experience and by following colleagues recommendations. The photograph and science section of the conservation department is currently investigating a selection of adhesive and attachment systems for the display of resin coated photographs. Here you see an overview of the studies on adhesives for RC papers to date. In 2004 MoMA investigated new adhesive formulations for polyolefin surfaces and building on that research, this study is aimed to add evaluating products now currently available and in use for conservators. We are approaching this investigation from two angles. On your left the first is an assessment and how a selection of adhesives on two carriers performs on one RC paper. The second on your right considers the materials attributes of classic RC papers to ones that are currently available. We purchase a variety of adhesive tapes and adhesive films potentially suitable for hinging RC papers. Our selection criteria was directed by our knowledge, our familiarity with the adhesives by available testing results such as BAT and audit tests but also by collegial recommendations and literature research. Admittedly the creativity for unusual adhesives also played a role in our selection. We conducted a number of preliminary evaluations to eliminate hinge combination that appear fundamentally flawed. In this pre-test products were scored according to shear strength and removability. Shear was scored on a pass failed basis and removability was ranked numerically. If a hinge was easy to remove it was a sign and a higher score. If it caused planar deformations, left residues or caused skinning or burnishing it was given a lower score. This image here shows you our heavy weight test where a hinge with a contact area of 0.5 square centimeter and a load of 270 grams gives the approximation of the shock a photograph in a crate in transit might receive if the crate suddenly drops. Originally 2% gelatin failed this test but we repeat this test with gelatin 5% on hollitex and the hinge remains suspended and this was quite impressive to us. Adhesives that did not make this cut are listed here on your left. There are the ones that didn't pass the shear test but on your right you have the results for the removability test. So 14 of the original 50 combination of adhesives and carrier passed failed in the pre-test. It's about 28% of the total 50. Here are all the candidates that made it and they passed the next level including 10 proprietary adhesives and 9 films and tapes which for now the core set of materials in this study. They are all commercially available and if you cannot find your favorite here please tell us and we can probably include them in our further testing. We tested then 25 adhesives and tapes supplied in a variety of methods. When possible we applied two different carriers Japanese paper and hollitex for a total of 50 again combinations of adhesives and tapes. The contact area for each is again 0.5 square centimeter. Each combination was tested in shearing and peeling test. Shearing and peeling strengths are respectively involved in flat heavy hinges. Each card tacked to the wall supports four RC paper samples with weighted hinges. The four duplicates permit us to average results and measure standard deviation. We calculated weight based on weight per area each hinge would support for most photographic prints. We selected a 20 gram weight which is slightly more than heavy weight paper. So this is our top row and this is the shear test. In the first month seven hinge for two different adhesives failed out of a total of 144 samples and these are goodie dots and Lascaux 303 but after seven months and this picture was taken like a week ago. Most adhesives appear strong enough for use as flat hinges so that means that all of these combinations of adhesives with their carrier they could be paper or hollitex are actually strong enough to hold that weight. The Lascaux 303 on paper remains adhere to the flat hinge but the Lascaux 303 on hollitex have all failed. We repeated this test three times to confirm the findings and always we had the same result. This underscores the importance of the bonding system and the carrier of the hinge which plays definitely a critical role. Goodie dot samples on both paper and hollitex carrier failed the test. For those of you who are not familiar with goodie dots this is an adhesive that past the PAT and it's essentially applied and it's applied to substrate in micro dot pattern. If a small portion of this hinge fails the remaining hinges would have to bear twice the load causing failure due to overloading. This product can eventually be perfect however for little weight papers. Okay it works. In PL test however there was much more action. Likely we documented the cards at all stages. The scale bar on each sample allows us to monitor and quantify the creep and this is the little scale that we applied to each sample. So we can track actually how each sample creep during this test. In this video we are going to scroll through the status of the PL test as of last week. This is after only four of the nine months experiments. The peanut boards contains again four samples with identical carrier Japanese paper or hollitex and of course for tapes this does not always apply. Red colorized fields are outright failures, yellow are borderline or questionable system and light green are so far looking good but the brightest green are so far the ones that didn't show any creep at all. Instances where two different colors appear simultaneously are instances where the carrier is having some influence on the bond strength. During installation and by the end of the first week a number of samples failed completely. We repeated this to verify that the application didn't affect the integrity of the bond. This was even repeated with lighter weights and we found they failed too. We will provide an update of the testing as completed in five months and with this video we want to show that there is a role that paper carrier influences the adhesive bond. Let remind you that we conducted all of these tests using just one type of RC paper and you will find in the presentation online the results like listed so you don't kind of get crazy looking at the images stopping the video. Now the last part of this talk is going to focus on characterizing RC paper in photography and now digital printing. We initially selected 13 papers. This includes vintage and currently available RC paper and RC type papers. We decided to include the digital papers because these materials are acquired by and displayed at MOMA and come into the lab on a regular basis. If the previous findings suggest the adhesive carrier interaction influences the bond the next part of this study examines papers and how their inherent properties might influence adhesion. Our collection is growing and we are getting additional paper both new and vintage. The resin in RC paper is polyethylene. This polymer is a polyolefin which is characterized by a long aliphatic non-polar chain structure consisting in only carbon-carbon and carbon-hydrogen bonds. The image on the right shows 100 microliter drop of water on polyethylene, a material that water has a very little affinity for. This is the cracks of the problem for RC prints in general. Adhesives that have a very good cohesive strength arising from their own polarity have a weak affinity for non-polar material like polyethylene. Wedding is the first step towards adhesion. Consider the long-term ramification of a bond between two materials that have a weak affinity for each other. If the substrate was more polar, however, like polyester or even an oxidized polyethylene, the water would more effectively wet the surface. We can quantify the difference with contact angle measurements which we will show in a few slides. We did ATR, FTIR on our RC paper samples and by inspecting the carbon-hydrogen we can see that not all RC papers are pure an oxidized polyolefins. The FTIR of these 13 papers suggests only a few are pure polyethylene, while some must contain components or oxidized polyethylene due to the presence of carbonyl or carbon-double bonded to oxygen. It is interesting to know that the two bottom spectra here that don't indicate any carbonyl are associated with the vintage papers. Sodi-oxidation is not age-related, rather manufacturers later learned that some polarity would improve inks and markers to stick to the verso. Obviously this opens up our option for adhesive too. In this detail of the previous spectra we see only the carbonyl absorption band. The samples colored out on the right have a carbonyl maximum at about 1720. This is an excellent agreement with the literature for polyethylene that has been oxidized by coronadis charge. You also find in the pattern literature for photographic papers coronadis charge being the method used to improve the paper's compatibility with inks. Traditional adhesives might be viable for these polar RC papers. Not every conservator then has half a TIR to identify the papers, but the contact angle test might suffice in assessing the paper surface polarity and therefore potential adhesive suitable for use. In this test we use a small mechanic mirror set at 45 degree angle with a few microscope slides to raise the paper so it could be easily be viewed in the reflected image with a microscope. The paper being tested was weighted down and a 100 microliter drop was placed on the paper. We waited for three seconds and captured the image. And you can see here with this video how that happened and it was so beautiful I guess. We wanted for the droplet, it's almost invisible at naked eye and theoretically non-destructive. You will find technical information about the mirror and the special pipette we used at the end of this presentation or also online. The angle of contact in the image was measured in Photoshop and it was great because you can actually have the right angle that you can just use in that software. And you can see here that not all RC papers have the same polarity. These are our results. Previously we feared that RC prints were non-polar, but this is only true for some papers, not for all. The RC prints were non-polar, but today this is much less likely to be the case. The image at the left concurs with the FTIR spectra. These systems are the most aliphatic or hydrophobic and the ones on the right have the strongest carbonyl signal. The Eiffel multigrade, which is this in yellow, is the paper we are using in our original adhesive testing because this is a true polyolefin, meaning it is hydrophobic and relatively difficult to get adhesive to stay stuck together. We are conducting surface characterization studies on all these paper samples to evaluate if and how surface roughness influences adhesion. In here, our light section, and this is actually the surface, of course, of the Verso. The differential interference contrast, micro-rackin imaging, and micro-rackin imaging with Henian's contrast, and we are using the workflow that Paul Messier used for the Thomas Walter project. So there are a number of next steps in the queue for us in the next months, including artificial aging, Wilhelm research, hinge removal assessment, and testing to evaluate the chemical stability of the image material with the adhesives. But suggestions for additional adhesives and carrier are more than welcome for further testing. Please send us your ideas, and I'd like to thank again Jay and Sara, FASC, and Center for Creative Photography. Thank you.