Preservatives and Odorants

Small amounts of a weak solution of phenol [carbolic acid], about a half teaspoon of the 1 percent solution to a pint. Drugstores will generally sell it up to about a 5 percent solution, this low concentration being deemed harmless.

Sodium orthophenyl phenate [trademark "Dowicide A"]--a powder obtainable in chemical supply stores. Small amounts [1/4 teaspoon to a quart of binding solution] will effectively preserve gums, casein, and glues.

Another older but effective preservative for gum solutions is beta-naphthol used in small amounts.

A 4 percent solution of formaldehyde. Formaldehyde is likely to react erratically with some binders and is better suited to industrial than to amateur use.

The odor of water paints is sometimes a little disagreeable; a [p. 163] few drops of any pleasant odorant will correct it. Care must be taken not to perfume the product too strongly, for that will usually be more objectionable than the natural smell of the paint. A "clean-smelling" material such as oil of cloves or sassafras is more appropriate than sweet, flowery odors. Oil of cloves also has a mild preservative action. [pp. 162-163]