Aluminum potassium sulfate

Efflorescence on ceramic plate

Description

A white odorless powder with transparent crystals. Aluminum potassium sulfate occurs naturally in the minerals Alunite and leucite. It has been used since ancient times as a Mordant in dyeing textiles and for tawing skins. Aluminum potassium sulfate, or potash alum, is also used as a filler in Paper, Cement, and paints. It is used to harden Gelatin, Plaster, and cement. Potash alum has also been used as a substrate in the preparation of lake pigments.

Chemical structure

Synonyms and Related Terms

potassium aluminum sulfate; aluminum potassium sulphate (Br.); potash alum; alum NF; potassium alum; kalinite; alum flour; alum meal; cube alum; alumstone; common alum

Risks

• Noncombustible.
• Harmful by ingestion and inhalation.
• Contact causes irritation.
• Fisher Scientific: SDS

Physical and Chemical Properties

Soluble in water. Insoluble in ethanol.

Composition	Al2(SO4)3-K2SO4-24H2O
CAS	7784-24-9
Mohs Hardness	3.5 - 4.0
Melting Point	92 C
Density	1.75 g/ml
Molecular Weight	mol. wt. = 474.38

Resources and Citations

• Irene Bruckle, "The Role of Alum in Historical Papermaking", Abbey Newsletter, Volume 17(4), September 1993. Link

• G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 32, 33

• Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993

• Hermann Kuhn, Conservation and Restoration of Works of Art and Antiquities, Butterworths, London, 1986

• Rosalie Rosso King, Textile Identification, Conservation, and Preservation, Noyes Publications, Park Ridge, NJ, 1985

• Palmy Weigle, Ancient Dyes for Modern Weavers, Watson-Guptill Publications, New York, 1974

• Susan E. Schur, Conservation Terminology: A review of Past & Current Nomenclature of Materials, Technology and Conservation, Spring (p.34-39); Summer (p.35-38); Fall (p.25-36), 1985

• Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979

• Book and Paper Group, Paper Conservation Catalog, AIC, 1984, 1989

• Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976

• The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983

• A Glossary of Paper Conservation Terms, Margaret Ellis (ed.), Conservation Center of the Institute of Fine Arts, New York City, 1998