In road marking, coverage rate (m² per tonne) is directly controlled by paint density - the solid density measured after the molten material is cast into a 2 cm cube mold and left for 24 hours.
The formula is clear: Coverage = 1 ÷ (thickness × density). With a fixed thickness, higher density means fewer square metres per tonne.
For a 10,000 m² job at 2 mm thickness, you need 20 m³ of solid marking. At 1.8 t/m³, that's 36 tonnes; at 2.3 t/m³, it jumps to 46 tonnes - a 10-tonne difference from density alone. Coverage drops from about 278 m²/tonne to only 217 m²/tonne.
Ignoring solid density can throw off material estimates by over 25%, causing shortages, waste, or budget blowouts. Always request the supplier's solid density report and calculate exact tonnage using the formula. That's the only way to truly control costs and predict coverage rate.
