Re: How to store zinc and copper etching plates?

#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
Helena