string-proof

Century Dictionary and Cyclopedia

1. n. In sugar manufacturing, a method of testing boiling sugar syrup to ascertain when it reaches a condition in which it begins to strike, or crystallize, and the degree of crystallization at any stage of the process. A drop of the hot syrup is placed on the thumb, allowed to cool, and touched by the forefinger; then the finger and thumb are drawn apart. The syrup draws out into filaments, the degree of crystallization being indicated by the breadth, length, and consistency of the threads or strings. Touch-proof or touch is the same test applied to the syrup at another stage in the boiling, when, on separating finger and thumb, the syrup forms a thin film which, when examined by transmitted light, shows the size of sugar crystals suspended in the syrup.