Q: Several years ago, my aunts gave me my grandfather’s 1948 casket flag, pre-statehood of Alaska and Hawaii. I’ve wanted to build a display box for the flag since then; however, I understand that certain woods and finishes are acidic and may not be archive friendly. Do you know which wood and finish would be safest to use to make an archival display box for this flag? Also, I’d like to place glass in the front so that the exposed portion of the flag doesn’t fade. Do you have any suggestions about what would be best to use for this type of protect?
A: There are certainly strategies to avoid acid in both wood and finish. Tannin plus moisture forms tannic acid, so choose a low tannin wood like maple, birch, aspen or holly, and avoid high tannin woods like oak, walnut, mahogany and cedar. To further isolate any tannin, seal the inside of the wood frame, the portion facing the flag, as well as the outside. Let the finish fully cure for four to six weeks before sealing the flag in the case.
Finishes that use acid as a curing agent include conversion varnish, catalyzed lacquer and pre-cat lacquers, so I’d avoid them. Instead, choose water-based or oil-based polyurethane, or lacquer. Shellac is OK, but I avoid shellac on anything that is adjacent to glass because ammonia-based glass cleaners can soften and damage shellac.
Finally, choose a UV blocking glass, since the UV portion of light is most responsible for cloth’s fading and degradation. The right glass can block up to 99 percent of UV rays without any color alteration. Thus the flag will be protected, but you’ll still see its colors clearly and without distortion. You can buy UV blocking glass from your local picture framing suppliers, or from online vendors.
Image #2: Polyurethane Gel
Image #2 Original Caption: If you’re making a box for precious
archival material, there are important strategies to follow when it comes to species, finish and glass selection.