3) My version of your horse brass experiment, but the bas relief placed on a hotplate, the cloth over the top, and then silica sand poured over the top of that to hold it down and fill in the valleys. The first attempt (BasRelief2) is on setting 2 on my hotplate (about 130C) and the second (BasRelief4) is at setting 4, which is about 250C, but its difficult to measure. (BasRelief4 will have to come separately as Hotmail is getting touchy about overload. Watch this space!)
It looks as if I might have just caught the UV only temperature on BasRelief2, as the visible image is so poor I can’t even tell which way up is it!