Field marking dusts are generally created using ground calcium products. These limestone-based materials are located in deposits all over the continent but were formed differently depending on location. In the mountainous regions along the east and west coasts, the limestone deposits were subjected to tremendous heat and pressure during formation. The result is a metamorphosed limestone commonly known as marble. Limestone deposits formed between the two mountainous regions, in the central part of the continent, usually will be softer material formed by a sedimentary process.
Differences in particle size, shape and hardness of these two different materials dictate brightness and flow properties of their respective ground material. The one common denominator with these products though is that when they are ground, they all have fairly angular surfaces to the particles. It is this angularity that causes the materials to mechanically interlock and bind up in the hopper. The result is bridging and a reduced flow through the dry line marker. When the chalking material is poured into the hopper, air is introduced and fluffs the material so that it flows better. As the marking machine is moved along, the vibration slowly settles out the air and the particles start interlocking. The particles become tighter and tighter compacted in the hopper and bridging occurs. This greatly reduces or stops flow of the marking material through the machine.
The best way to reduce this problem is to only pour enough material into the hopper that is needed to line that field. All of these materials are widely mined and produced across the continent and are inexpensive when purchased near enough to their processing location so that high-cost shipping can be avoided.