well, there are other techniques like writing with lemon juice and when it dries you can't see it unless you put it near the fire. I think it is like that...
That is all nice, but do you think soldiers in the war had lemon at their disposal? 😀 Not even those had lemon, who were at home and not in the front line.
so you have practiced fencing?
Yup, for a couple of years.
😏 with milk could also be done
How I love to take pictures of fencing. I have many... ☹️ on the hard drive that is broken they are sequestered there.