How to store zinc and copper etching plates?

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    • #133516
      Martha Grenzeback

      We have unearthed a collection of wood-backed zinc and copper etching plates (along with a couple of woodcuts) dating from the 1920s-1940s–they were used to print some of our old library publications and bookplates. They are currently in individual manila envelopes, most of which are dirty and torn–the plates themselves seem to be in good condition. What is the best way to store them? In archival boxes? Should they be wrapped in something?

    • #133527

      Hi Martha, I dealt with rehousing a number of copper printing plates (early 19th century) by cutting pieces of archival matboard slightly larger than the plates and binding three edges together (two shorts and one long) with linen tape to create a “folder.” Then, when inserting the printing plate, I wrap a piece of twill or tying tape around it with two ends sticking out so that you can “pull” the piece out. I store these in archival record album boxes that stand upright, from Gaylord. On the outside of each “folder” I have written the accession number of each piece and printed an image of both the plate and its “positive” print. Would be happy to show you pictures if you’d like!

    • #133526
      Martha Grenzeback

      Thanks, this is helpful! I like the idea of having somewhere to attach an individual catalog number and an image of the print.

    • #133525
      Lisa Vedaa

      Whitney, is it possible to share your photos in this discussion, and/or would you be willing to? I am curious to see your system and think I could find it quite helpful. Thanks!

    • #133524

      Amazing, I’ve just written a rather substantial report for my internship placement recently, and also a rehousing proposal on this exact subject.

      The research I did indicated that from a Conservation/Preservation perspective, it is best to store metal plates flat.
      Most libraries and archives (as well as professional artists) I interviewed already do so.
      The reasons are many, but the main motivation is the ductility of the metal (which is at greater risk of damage while supporting it’s own weight in a vertical position).

      It’s likely you would want to maintain the readable surface of the printing plates, and that means mitigating risk factors for corrosion, a low RH is helpful, along with keeping the plates free of dust. Enclosures are a great idea. (If you have the budget and time it’s great that you could put images of prints on the enclosures!)

      As a Conservator, I would highly recommend separating the zinc from the copper plates, as the two metals together are somewhat conductive to corrosion, and can increase risk of corrosion particularly for the zinc plates. (Zinc being a less noble element, it will become a sacrificial metal).

      I’d love to be more helpful if I can. I’m new to the forum, and hope I haven’t overstepped my bounds with any of my eagerness and information.

      Best Regards,
      Shannon Jill Bray

    • #133523
      Amy Lucadamo

      Thank you for the info. Shannon, just a quick follow-up. Like Martha said in her original question, the plates in our collection are backed with wood. They are about 2″ thick. Should those also be stored flat and if so does it matter if they are stacked or whether the metal faces up or down?

    • #133522

      I would store them flat, face up (metal side up) in acid-free enclosures, making sure that the enclosures were supporting the weight, not the plates themselves. Depending on the conditions they have been kept in (you don’t want to subject the wood to a rapid change of humidity) I would keep them in stable, dry conditions. If the store does not have good environmental controls, I would keep the packed plates in an outer container (e.g. a polythene or polypropylene box with a good lid, with a drying agent (e.g. cassettes or bags of silica gel) to maintain a chosen relative humidity (RH). If I had to keep the items in boxes to maintain a stable RH, I would line the box with polythene foam (Jiffy foam or Plastazote) and make sure that the lowest plate is supported off the bottom of the box with sufficient padding to allow airflow around and below it as I wouldn’t want to risk volatile compounds possibly gathering around the lowest plate.

      The most important thing to do is to have a good record of their condition now (including clear photographs of all sides) and monitor them for changes regularly. I would make sure I had some photos of the surface with a raking light as this will help detect surface changes (e.g. the beginnings of corrosion). I wouldn’t allow anyone to handle them without wearing clean nitrile or similar impermeable gloves. I would avoid latex gloves because of the risk of residues of sulphur compounds or alkalis.

      Is the wooden backing a ply made up of different layers, or a single piece of wood? If it is a ply it will be more dimensionally stable (less prone to large splits and cracks) but you have the potential problems of adhesives giving off volatile compounds as they age, and of the layers peeling apart or delaminating.

      Hope this helps

    • #133521
      Lisa Vedaa

      Thank you, Shannon and Helena! This is very helpful information!

    • #133520

      Amy, yes wood backing does change things a little, yes! In my excitement I skimmed over this detail, but I did also have some wood blocks in the collection I was working with as well. It would reason that the wood might support the metal to store the printing blocks in a vertical position, but if you have the space flat storage is best. We do what we can! Regardless what kind of storage system used, the plan should also consider preventing the metal from being scratched, dented, or otherwise banged around in an enclosure.

      Helena is quite right about placing the metal side up, and that wood requires a stable RH. To add to this, it would help to unwrap the plates from their manilla envelopes gradually to buffer RH and prevent dimensional changes in the wood block.

      Using a dessicant is a fantastic idea (I was also researching Anoxic for my project, but had a lot of organic resins on my plates) but a desiccant does require a sealed container, and some amount of cost and maintenance to replace the sorbent over time.
      The concern about using an airtight container is as Helena mentioned, that wood and wood products tend to off-gas organic acids that are corrosive to metal. There is also the question of how the plates have been adhered, possibly with an adhesive? Possible volatiles.

      These are interesting posts!

      Helena, I love your suggestion about taking photos with raking light. I could have used that on my project!

    • #133519
      Martha Grenzeback

      Thanks for all the great input!

    • #133518

      The question should be whether u consider a significant artefact the woodpiece connected to the plates or if the adhesive between them has lost strength so as to be able to separate the 2 incompatible materials: wood and metal plates. If the separation is easy task then i would recomment to avoid all future deterioration, since wood (to non stable conditions) can lose shape and this may cause loss of shape to plates as well. Wood may be good “protector” as backing for humidity flunctuations, but it also emits volatile organic compounds to all close materials. U can use strips of clear polyester to move them, scavengers for volatile organic compounds and silica gel for buffering. Storing with acidic free materials as mentioned before but i would also recommend to wrap them with acid free tissues, acid- free thick papers (to the back of wood,to absorb possible humidity dryness that can cause spots and absorb them) and melinex, polyester sheets on top of plates. U can use different methods for storage in boxes, but remove also envelopes that are dirty and torn and treat them as paper artefacts separately. In case u can separate plates from wood then u can also preserve wood separately.

    • #133517
      Amy Lucadamo

      Thank you all for the information. This was really helpful. My plates were designated for deaccession by my predecessor, but I find them interesting & informative artifacts. I will have to take a closer look and evaluate their condition to decide what time and resources I want to spend on their re-housing.
      Thanks again!

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