Hard Formula is approximately the same viscosity as 30 wt. motor oil. It is easy to apply a thin, shellac-like clear coat that will cure in seconds when irradiated with sunlight or our UV flashlight. This product is a very durable aliphatic urethane which characteristically does not yellow with age. Usage tip: Apply in shade. Irradiate with intense UV light for ONE SECOND. Wait 15 seconds. Irradiate again for one second. Wait. Complete with 30 full seconds UV light. This technique will reduce heat & shrinkage