The percentage of GILSONITE ASH is considered to be an important factor in the analysis of natural bitumen, soils can be classified according to their type:

• Under 5% (suitable for color and ink industries)
• Under 10% (suitable for drilling and casting)
• Under 15% (suitable for construction, drilling mud, asphalt, casting and insulation)
• Under 20% (suitable for construction and insulation)
• Under 25% (suitable for construction and insulation)
The most standard test available for natural bitumen ASH is ASTM-D3174