Has the formula for making crayons changed over the years to make them harder?

The earliest of crayons didn't have uniform tips like they do today. Most of them were hand carved or even when they were machine carved, the didn't have the flat tip they do today; they went to a very fine point. Another change you don't see is that many assortment boxes contained a brass or metal crayon holder so you wouldn't break your crayons while coloring with them. Crayons were generally very small in early years. They thought that small children had small hands and therefore needed small crayons whereas they've since realized that larger oversized crayons make it easier for small children to control. The sizes have changed over the years. The most common sizes found in the late 1800s and pre-1920 era were 28, 14 and 7 and none of those sizes are now available. They've switched to 8,16,24,48,64.