BASF MasterSeal 590 in a 10 lb can, formerly Thoro Waterplug, is a one-component, quick-setting, Portland-cement-based hydraulic repair mortar compound that instantly stops running water through holes or cracks in concrete or masonry. Masterseal 590 - Waterplug - expands as it sets to lock into place even under constant water pressure. Masterseal 590 is very fast setting so it can stop running water and develops high strength quickly, is fully hydraulic so it can set above or below water, is shrinkage compensated so it expands to lock in place and is one component so it mixes easily with water only. Masterseal 590 - Waterplug - is ready to topcoat in 15 minutes with appropriate product to minimize downtime and with its durable, non-metallic, non-gypsum formula it maintains volume stability over time. Masterseal 590 can be applied in cold temperatures and put to use in any weather conditions.