Talk:Conservation and restoration of photographic plates

Final Project Outline Review
Hi Marena,

Your outline looks great and seems to serve as a very strong foundation for your article starting out! Your outline closely follows Wikipedia guidelines. Your structure is easy to follow and provides a comprehensive and detailed overview of the conservation and restoration of photographic glass plates. I like that you broke down your article into Agents of Deterioration first, followed by Preventive Conservation and Conservation Treatment. This really allows the reader to understand the cause and effect of the deterioration of the photographic glass plates, and also get a sense of the sequential process of the conservation and restoration of these objects. The sources you have are solid and thorough. I was also going to recommend looking at CAMEO, but after looking, I saw that they didn't have much helpful information on photographic glass plates. It looks like you have rounded up the best possible sources of information. The only suggestion I have for your outline overall is to include your full list of references under the reference section. At least for me, I found it easier to keep track of my citations when I had my reference list handy at the bottom. I am looking forward to reading your article!

-Peri Pboylan3 (talk) 16:59, 31 March 2018 (UTC)

Marena, Your outline looks very thorough and well organized. I think the way that you structured your outline, with information just about photographic plates first followed by agents of deterioration, prevention, then treatment, is an excellent way to introduce the topic to people who aren’t familiar with it. One suggestion I have would be to use the term “photographic plates” rather than “photographic glass plates” as the main Wikipedia page uses the term “photographic plates”. I liked that you included a separate section for the storage of broken plates, as it is much different than storing unbroken plates. I was a little confused by the mechanical damage/human subheading in the agents of deterioration section. I assume that means damage from a camera or other device and then being dropped by a person? If that’s the case I would put them into separate categories. I would suggest having the references listed at the bottom of the page for easy access. I would also add links to any related Wikipedia pages at the bottom as further reading. It looks like the list of references you have is extensive and comprehensive, so I don’t have any suggestions there. One thing in terms of Wikipedia style guidelines I would look out for would be making sure that the article title and section headers all follow sentence case rather than title case.

-Kelsey — Preceding unsigned comment added by Kmanahan1221 (talk • contribs) 22:07, 1 April 2018 (UTC)

In reviewing this Wikipedia page, there are a few edits that would behoove and add more content to help viewers understand ideas surrounding the topic of the Conservation and Restoration of Photographic Plates. Here's an outline of these edits that follows the current structure of the page as is. What are viewer's thoughts?

HISTORY 'Bold text' Neither the Gelatin Dry Plate and the Collodion Wet Plate are linked to outside sources within the wikipedia. The use of the term, “bound” in the definition of a photographic plate is troublesome. In such the instance as the gelatin dry plate, the image itself is not bound to the glass, as it is suspended in the gelatin emulsion. A better choice term would be that the image is layered on top of the glass support. It is also important to note in the initial discussion of the history that this binder is dependent upon the type of photographic plate as well as the time period. Depending upon the time period, there can be variants to the binder and thus, the chemistry of the image. This is extremely important with conservation and restoration because it helps the Conservator prevent chemical reactions. It is for this reason that discussing the process for creating a photographic glass is also important. In the case of the Wet Collodion, the image is run under a wash bath to stop the development of the image. The fix is mentioned under the page as stabilizing the image, but it does so by removing unexposed silver halide crystals. Likewise, the word and idea of this fix bath needs to be linked with other Wikipedia pages. The fix bath will ensure that the remaining silver halide crystals are no longer sensitive to additional light exposure.

Wet Collodion Though the emulsion for the Wet Plate is discussed, there is no indication of what the emulsion is composed of. Collodion is cotton dissolved in nitric acid. Given that this was both complex and dangerous to produce, it was often purchased by the photographer. Once dissolved, iodide was added. Over time, Bromide was added to help the image be more sensitive to light. Sometimes albumen (made of egg whites) was used to help the collodion stick to the glass plate. Pyrogallic acid or ferrous sulfate was often used to develop the latent image, then sodium thiosulfate (also known as hypo) or potassium cyanide was used to fix the image.

Gelatin Dry Plate Though the Gelatin Dry Plate was introduced in 1871 as an alternative process that removed the need for a portable darkroom, it was not commercially viable until 1879. The shelf life was that of months. To make the gelatin dry plate, the glass was cleaned, polished, and treated to ensure the gelatin would stick to the glass. Treatments of the glass include thin coats of gelatin, albumen, chemical etching.

AGENTS OF DETERIORATION Traditionally there are ten accepted Agents of Deterioration: dissociation, fire, incorrect relative humidity, incorrect temperature, light, pests, pollutants, physical forces, thieves, and water (Government of Canada). Photographic plates face risks of deterioration from both external forces and through the plates own inherent vice. In order for a conservator to create an appropriate plan to protect against deterioration or damage, the agents of deterioration that are threatening the stability of the photographic glass plates. The primary agents of deterioration for photographic glass plates include the following: Relative Humidity & Temperature Relative humidity (RH) and temperature are two of the most common threats to photographic plates and can determine their longevity.[7] As with all material collections, an overall high temperature in combination with high humidity can then lead to mold growth and attract pests. Photographic plates face significant structural and chemical challenges unique to their structural make-up. There are two types of photographic glass plates, collodion wet plate and gelatin dry plate. Structurally, collodion wet plates are held together with a specific type of emulsion, made using a silver halide mixture in gelatin. Fluctuations in RH can strain the adhesion of the emulsion, causing the gelatin to expand and contract. Additionally, the strain from incorrect RH can cause emulsion to crack or separate along the edges.[8] As where in gelatin dry plates, high humidity can cause mold to grow on the emulsion.[9] High levels of humidity can cause glass plates that are stored incorrectly to stick together, compromising the photo on the plate. Increasing the relative humidity can cause deterioration of other elements as well such as the silver, varnish, and glass support. Decreasing the RH will cause deterioration by leading to the flaking of the binder and dehydration of the glass.[10] Light Photographic plates, along with all photographic materials, are very sensitive to light. Extensive and ongoing exposure to light can cause significant deterioration that is irreversible. Sunlight is the most damaging type of light to photographic plates. However, indoor lighting and other forms of UV lighting all pose a threat to photographic plates causing fading and yellowing.[11] Light is especially threatening to color photographic materials as it causes accelerated fading of the color dyes.[12] Exposure to light could deteriorate and lead to discoloration of the pigments present on the plate. Air Pollution Air pollution can pose a threat to photographic plates through poor air quality and dirt that can damage the materials. This can include dust to gaseous pollution in an urban environment. Air pollution can cause fading of photographic materials. If a plate is subject to poor air quality, removal of the debris must be done with care using a cotton cloth, if done incorrectly the glass might be subject to abrasions (Cappucci, T,. n.d.). Other sources of air pollution include "photocopying machines, construction materials, paint fumes, cardboard, carpets, and janitorial supplies," and other types of outdated media.[13] Material and Chemical The glass composition of photographic plates can be a factor of deterioration. Due to poor quality or an inherent vice, "sick glass" can occur. Environmental conditions are usually linked to the increase or presence of this glass corrosion. The effect of "sick glass" can be weeping and crizzling which can be caused by excessive alkali present and a lack of stabilizers.[14] Weeping involves droplets forming on the glass that appear as small crystals. This type of deterioration is especially threatening for cased photographs because the cover glass could be corroded and damage the photographic image underneath.[15] Corrosion of the glass plate support can also damage the image layer by causing the lifting of the binder and varnish layers.[16] The other chemical components of glass plate negatives can also be threatening agents of deterioration. For instance, the silver image layer could possibly undergo oxidative deterioration which can lead to fading and discoloration. Additionally, the collodion binder itself is made up of cellulose nitrate which is known to be a highly flammable compound. Most of these agents of deterioration are the result of poor chemical processing as result of inherent vice, but they are usually accelerated by poor environmental and storage conditions.[17] Physical Glass plates are rather stable dimensionally, but they are also fragile and brittle.[18] Glass is brittle, it is highly susceptible to breakage, cracks, and fractures. This can be caused by human error; including dropping or bumping the glass plate, or it can be caused by failure of storage equipment, housing, shelves, etc. which may lead to an impact to the glass. Certain types of breakage and stress states affect the image layer and binder in different ways. Types of breakage:[19] Impact Break - point of impact and surrounding radiating arcs. Cracks - run perpendicular to applied stress. Blind Cracks - breaks do not carry through the whole shard of glass.

PREVENTATIVE CONSERVATION Though this area of the page is rather thorough, there is quite a bit missing on the storage requirements that will help prevent exposure to agents of deterioration. Though it is necessary to have a four-fold envelope to house the plate that is both acid and lignin free, it is also important to ensure that it is PVC, dye, sulfur, and alum free. In regards to the acidity, it is recommended that the pH of the paper is between 7-8.5. The Image Permanence Institute offers what is called the PAT or Photographic Activity Test. The use of the PAT has become a standard in the preservation of photographic plates. The PAT, “explores the possibility of chemical interactions between photographs and a given material after prolonged contact”. A link to the PAT should be included. The PAT should additionally be added as a Resource. Broken plate storage. Though most elements are included in this area, with broken plate storage, it is only recommended to stack broken plates 5 plates high. Unlike intact plates, with broken plates, they must be stored horizontally. Due to the weight of plates stacked upon each other, too much weight can cause additional breakage and damage. Shelving. Under storage conditions, shelving is something that is not discussed at all. It is best NOT to house images in a wood cabinet or crate, as the chances of termites and damage to images is high. Wood shelves are also susceptible to off-gassing compounds such as acetic acid and formaldehyde. Wood shelves also tend to possess a finish or a glue that can also cause off-gassing that will result in chemical reactions with the images. Lastly, with wood shelves, it is hard to ensure the shelves are sturdy enough to hold the weight of the plates. Because of all this, steel cabinets are preferred. Under preventative measures, environmental conditions that are ideal are discussed. One point worth mentioning is what is considered minimal and acceptable fluctuations for RH and temperature. Ideal temperature fluctuations is +/- 2 degrees and with relative humidity, it's +/- 3% RH. Though cold storage is okay, with proper acclimation periods for the image to room temperature. Freezer storage (unlike for film images) is not recommended. Cleaning is necessary as a preventative tactic for photographic plates. However, improper cleaning can cause the accidental removal of the image or can cause flaking of the emulsion. It is best to use an unused paint brush and very gently, from the center, outward, brush over the photographic plate. To clean the underside, dip a cotton ball or cotton round into a cup of distilled water, and work from the middle of the plate to the outside. Water will wash the emulsion away, causing the image to be lost forever, be careful to ensure this cleaning treatment is only used on the glass support and not the emulsion side of the plate. Under handling it is important to note that cotton gloves can cause the glass to slip from the holder's grip, but also that cotton gloves are susceptible to snagging on the emulsion (if the emulsion is flaking) or on the edges of the glass support.

CONSERVATION TREATMENT This section mentions many of the methods for conserving and repairing broken glass plates however there can be more information added and a restructuring of the section to make it flow better Add a section as to how the broken sections should be handled. Neoprene gloves should be used instead to protect the emulsion from fingerprints that will cause deterioration over time. Glass fragments should be handled as little as possible. A padded (foamed polyethylene) and tight weave tissue or Sintered Teflon lined box should be used for fragments. Do not let the fragments come into contact with the foam; any lifting binder will be very susceptible to snagging. Handle glass plates by two edges and carry flat. Do not handle the corners. Work on a clean, dry, padded surface: such as a sheet of thin Ethafoam covered with blotter. Place glass plates on a flat surface, binder side up. Never place any pressure on the plate: label sleeves before placing the plates in them. Never stack bare plates. High use plates should be duplicated. Methods of assembly Virtual Assembly in Photoshop In the case of an object that has been broken into many shards, initial assembly should be performed by scanning the shards into files that can be manipulated in PhotoShop to determine their positions. This minimizes handling, protects the binder and any mirroring and reduces the chance of further damage to the glass. It may be more convenient to photograph or scan the shards all at once so that they will have a precise size relationship to each other. Each shard should then be selected and made a separate layer. Select the first layer to be manipulated, and select the rotate function under edit > transform > rotate. Rotate the piece until it reaches an approximation of the area in which to be moved and drag it into place. Select and manipulate the rest of the layers until the object is assembled. This method of assembly will not only protect the delicate emulsion and glass from the further damage that can occur by physically manipulating the shards, but will give the conservator an idea of any other problems with the piece, such as missing shards. Likewise, through digital reproduction, research and study of the plate is still possible without the risk of further damage through continual handling. Inclined Assembly In this assembly method, adhesive is applied to the shard interfaces, which are then assembled on an inclined plane on a sheet of Mylar or a Silpat. The edges of the assembled plate are shored up with matboard, and an additional light weight is placed on the top side of the plate during curing. This method requires cleaning of the bottom side of the plate, which is against the inclined plane because capillary action tends to suck the adhesive out of the fracture interfaces. Adhesives used - to add what is already there Pressure sensitive tape Plastic tape, while easy to use and completely removable, has a flexible plastic carrier that gives minimal support. Sticky wax As the pieces are assembled, sticky wax, such as that used for lost-wax casting in jewelry making, is very useful for holding the shards in place.

Methods of application of adhesive Italic text Wicking - already mentioned Direct application When repairing a broken plate on an inclined plane, the adhesive is applied directly to the fracture interface and the shard is placed directly next to its corresponding shard on the inclined plane. Information is taken from an already sourced resource in this section

RESOURCES These are resources that should be linked within the page as they are certainly helpful! Terri Cappucci: Cappucci specializes in the preservation of glass plates and photographs using the method of Wet Collodion plating. http://terricappucci.com/glass-plate-collection.html Royal Museums of Greenwich. https://www.rmg.co.uk/stories/blog/conservation/conserving-gibson-glass-plate-negatives Canadian Conservation Institute: Care of Black-and-White Photographic Glass Plate Negatives. https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/canadian-conservation-institute-notes/care-black-white-photographic-negatives-glass-plate.html Wiki a Collaborative Knowledge Resource: PMG Preservation of Glass in Photography https://www.conservation-wiki.com/wiki/PMG_Preservation_of_Glass_in_Photographic_Materials CulturalHeritage.org : The Glass Plate Negative Project at the Heritage Conservation Center https://resources.culturalheritage.org/pmgtopics/2013-volume-fifteen/17-T15_Tay.pdf Image Permanence Institute. (n.d.). Photographic activity test. Retrieved April 27, 2022, from https://www.imagepermanenceinstitute.org/tests/pat.html Museum of the White Mountains. (n.d.). Cleaning, scanning, digitizing and Rehousing: A journey with glass plate negatives. Retrieved April 27, 2022, from https://www.plymouth.edu/mwm/intern-story-2/

REFERENCES New links to be added to existing references that are currently broken Reference #1,4, 5, 6 - https://s3.cad.rit.edu/ipi-assets/publications/negatives_poster_booklet.pdf Reference #3 - https://www.parisphoto.com/en-gb/fair/glossary/negatif-sur-verre-collodion.html Reference #40 - https://learning.culturalheritage.org/caring-treasures New references Cappucci, T. (N.D.) Glass Plate Negatives. terricappucci.com http://terricappucci.com/glass-plate-collection.html

These are new references that could be added that helped us gather the additional information above and need to be linked with the information. Government of Canada. (September 26, 2017). Agents of Deterioration. Government of Canada. https://www.canada.ca/en/conservation-institute/services/agents-deterioration.html Herskovitz, R. (1999). Storage of Glass Plate Negatives. Minnesota History Interpreter, 3–6. Retrieved April 2022, from https://www.mnhs.org/sites/default/files/lhs/techtalk/techtalkjuly1999.pdf. Voellinger, T. (2009). Cold Storage for Photographs Collections - An Overview. Conserve O Gram, 14(10), 1–5. Retrieved April 27, 2022, from https://www.nps.gov/museum/publications/conserveogram/14-10.pdf.

Hollinkris (talk) 19:35, 27 April 2022 (UTC)Hollinkris Uprightdownleft (talk) 20:40, 27 April 2022 (UTC) Amber2486 (talk) 23:02, 27 April 2022 (UTC)