LETTER TO THE EDITOR

1 PRECIPITATED CALCIUM CARBONATE

PAM HATCHFIELD of the Museum of Fine Arts, Boston, has brought to our attention that Mayco Industries' calcium carbonate powder is not precipitated, and is therefore not recommended for use in the cleaning of silver (see Wharton, G. et al. 1990. A comparative study of silver cleaning abrasives Journal of the American Institute for Conservation 29: 13–31.)

Fisher Scientific, Mallinkrodt and other chemical suppliers sell precipitated calcium carbonate in quantities over 500 g. As of yet, we have not found a source for smaller quantities. If anyone has information, please let us know.—John Griswald, Associate Conservator, Glenn Wharton and Associates, 549 Hot Springs Road, Santa Barbara, CA 93108; (805)565-3639.

2 LETTERS WELCOMED

THE EDITOR welcomes comments from readers both in general and on specific papers. Please indicate if your communication is intended for publication.