Thread: Silver Nitrate Dying

Interesting project. As I recall, Neil Miller was a photographer as well as a strop-maker. I have used silver nitrate quite a bit with old photographic procedures, and the solution strength as given (~1.5%) strikes me as being on the weak side. It might be interesting to cut the water volume in half (assuming that the scales would be immersed in the resulting solution), to see what the result is, darkening and so forth. If the only exposure to ultraviolet light has been ten minutes under artificial illumination, and no stabilizer has been added afterwards, it may darken further with exposure to natural ultraviolet light. Also, silver-nitrate embedded surfaces darken considerably when exposed to tannins, so you could also experiment with soaking the scales in a very strong solution of tea, or coffee, followed by balsamic vinegar. To bleach the scales, a strong solution of salt water could be used, which acts as reducer and mild stabilizer.

It looks like you used a metal stirring rod. In working with silver nitrate, one should only use glass (preferable) or plastic vessels and tools. Metal will contaminate everything. Distilled water is preferable to tap water so as to avoid contaminants there. Wear nitrile gloves as silver nitrate
stains the skin, and safety goggles to protect the eyes, but I suppose you know this.

Edit. As an afterthought, old accounts of salt-printing speaking of "bronzing," whereby the silver has been reduced completely by an over-exposure to ultraviolet light. I've never worked with bone; but if "bronzing" has been achieved, it might account for the dark, golden effect that you describe. And if so, then it is possible that the result will remain stable. As I recall, weaker silver-nitrate solutions are more light-sensitive than stronger ones, so that would seem to point towards a possible "bronzing." Give the scales a long exposure to natural daylight to know for sure. If there is no change, then such a state probably has been reached. Without protective coats of wax, varnish, etc., exposure to mild alkalis found in shaving soaps may lead to staining or darkening.