7 CONCLUSION

BOTH SILVER CYANIDE and chalconatronite may be more common on museum objects than previously thought. They may not be readily apparent since their colors alter upon exposure to light so that they may be confused with more common less toxic products. For example, the darkening of silver cyanide can look like silver sulfide corrosion. It is imperative to remove silver cyanide because of its poisonous nature. No method is known to the author for removing silver cyanide corrosion without liberating hydrogen cyanide gas and/or causing at least microscopic etching to sterling silver. An aqueous 20% solution of sodium thiosulfate was chosen as a method which did not create hydrogen cyanide gas. Etching was kept at a minimum by careful timing and observation of the procedure which had been worked out beforehand on expendable blanks. All treatments to remove silver cyanide should be carried out in a fume hood. Any by-products should be disposed of properly after determining the current appropriate disposal method.15