excluding air would prevent oxidation, but I don't think it would stop acid from doing it's thing. also that serious level of archival protection would rather undermine what I was imagining to be an economical decorative wall hanging.



if you want to check the pH pool supply, garden, and many drug stores sell pH tests, or just google "pH test" and you will see all kinds of test kits, paper and liquid, lots under $10. some come on a roll like scotch tape and will be good for hundreds of uses, depending how much you cut. to use the paper ones the map will have to be wet, but given your process I don't imagine that would be a problem. just touch a test paper to your wet map paper, the test paper will change colour, you compare this to a key that comes with the pH tests and read the pH. well, technically it will be the pH of the water, but if the water has been in and on the paper for a while that should be close to the same. there is a chance that the colour from the test paper could get on your map paper so check on the back. assuming it is acidic I would then soak it in a base solution, rinse in fresh water, then retest to see how much the pH has changed and repeat as necessary. probably too much trouble for a disposable prop, but prudent for a framed antiqued map