I’ve heard mixed reviews about hot sanding kolmusim in order to make them hard – the idea is to form the quill when it’s soft – then put it in hot sand to harden it. I had to try it. I soaked the quills to soften them, cut them to my specifications (I find that cutting a hard quill often causes cracking – and often the slit doesn’t form well) then I heated up sand @ 250 degrees celsius and put in the quills. I must say that I am quite pleased with the results. The quills are hard – but formed to a precision I wouldn’t be able to attain with a hard quill. (Admittedly probably due to my lack of expertise with cutting quills.) Notice that the quill is opaque after it’s taken out of the sand – this is a sign that it is hard.