A short arc lamp is optimized for improved thermal performance characteristics. The temperature control pins includes a supporting pin for supporting a substrate, a heater being arranged within the supporting pin and is close to a top of the supporting pin, and a cooling system. The sealing means substantially maintains the pressure differential between the chambers by segregating high pressure fluid in the second chamber from low pressure fluid in the first chamber. A machine which can be set to mix the ingredients and water in the correct proportions on site is also described. The front and rear drums are rotated by a concentric clutch that is nested in the rear drum.