When sourcing chemicals like Potassium Nitrate, Barium Nitrate, or Aluminum Powder, purity is the most critical factor. You must ensure a purity level of 99% or higher to guarantee predictable chemical reactions. Additionally, particle size (mesh size) significantly affects the burn rate and effect; for instance, fine powders are used for flash effects, while granular forms are for sparks. Always request a Certificate of Analysis (COA) for every batch to verify chemical composition and moisture content, which should be below 0.2% to prevent degradation.