PVA Glue off-gassing causing corrosion?
SWMBO recently found three 9ct gold rings that were stored in a jewellery box I made for her a year ago had corroded to the point, in one case, of disintegration. The rings were held between cylindrical holders made by covering styrofoam with synthetic velvet. The fabric was stuck to the styrofoam using Titebond II, a cross-linked PVA glue. I've used this glue for the same application many times previously and never had any problem reported. A previous thread in this forum discussed corrosion caused by liquid drops of PVA glue, but a comprehensive google search has found no reference to off-gassing causing corrosion of jewellery.
However, a paper looking at off-gassing of PVA glues used for making and lining clam-shell boxes for document preservation used a test which included exposure of lead and copper coupons to heated PVA. The lead exhibited corrosion products while the copper showed blackening, indicating the presence of acetic acid.
In the bookbinding industry, a period of 30 days is recommended to allow for off-gassing, before use of the boxes. My recollection is that I completed my wife's jewellery box immediately before giving it to her, and making the ring holders would have been one of the last processes.
I'll continue to research this, but in the meantime, I suggest that if you're making and lining jewellery or stationery boxes with PVA glue, you allow a month or so before selling them or giving them away.