It is a white, granular or crystalline solid, highly soluble in
water producing an alkaline solution. A 1% aqueous solution
has a pH of 11.6. It is hygroscopic and incompatible with
strong acids.
Trisodium phosphate is used as a cleaning agent, food
additive, stain remover, and degreaser. The major use for
trisodium phosphate is in cleaning agents and the solution is
sufficiently alkaline to saponify grease and oils. In combination
with surfactants, it makes an agent for cleaning everything
from laundry to concrete driveways. Its use has
declined in the western world due to ecological issues
with waste products. It is also used for cleaning, degreasing,
and deglossing of walls prior to painting.
In the United States trisodium phosphate is an approved
flux for use in hard soldering joints in medical-grade copper
plumbing and is also used as an ingredient in fluxes designed
to deoxygenate nonferrous metals for casting. It can be used
in ceramic production to lower the flow point of glazes.
Trisodium phosphate is approved as a food additive in the
European Union (E number 339) and other countries. It is
used as an acidity regulator in a variety of food products.
