In cases where the complete preservation of the timber is of vital importance, and expense no object, Mr. Britton recommends that the timber should first be injected with metallic salt (as in Burnett's system), dried, and then creosoted. By this means the whole is preserved; the salts protect the heart, and the creosote the sap wood.
Oak Casings may be preserved from injury done by weather by two coats of boiled oil applied cold.
Several methods for preserving timber from fire have been proposed from time to time.
It is said that timber that has been thoroughly Burnetised will only become charred and not burnt by fire.
Some years ago the following means of protection was recommended by Sir F. Abel.
The wood having a smooth and clean surface is first painted over with a dilute solution of the silicate, then with slaked fat lime of the consistency of cream, then with a stronger solution of silicate.
Cyanite is a fireproof solution, probably containing a soluble silicate, which has been frequently tried lately, and apparently with success. It is stated that it will cover twice as much as an equal quantity of priming.
Tungstate of Soda imparts fireproof qualities to timber or fabrics covered with repeated coats of the solution.