The string was impregnated in soufa for about 30 seconds, pulled up, squeezed tightly and air-dried.
I ignite with an alcohol lamp. Basically, it does not ignite. Even if it ignites slightly, it extinguishes itself.
It seems that smoldering may remain in the string, but it is thought that increasing the impregnation of soufa will solve the problem.
This proved that hemp bags and the like can be made flame-retardant and flame-proof.