MasterSeal 590: Waterstop Repair Mortar


  • Nonmoving (static) cracks and holes with running water or moisture seepage
  • For immersion service
  • For anchoring vertical bolts
  • Basements
  • Foundations
  • Retaining walls
  • Sewers
  • Fast-setting
  • Fully hydraulic
  • Shrinkage compensated
  • One-component
  • Ready to topcoat in 15 minutes with appropriate product
  • Durable nonmetallic, non-gypsum formula
  • Formulation available for cold-weather applications
  • Stops running water; develops high-strength quickly
  • Sets above or below water
  • Expands to lock in place
  • Mixes easily with water only
  • Minimizes downtime
  • Maintains volume stability over time
  • Use in all seasons and climates

Product Data Sheet

Safety Data Sheet

Sealant Quantity Calculator

1 in stock (can be backordered)

MasterSeal 590: Waterstop Repair Mortar

MasterSeal 590 is a one-component, quick-setting, portland-cement-based hydraulic repair mortar that instantly stops running water through holes or cracks in concrete or masonry. It expands as it sets to lock into place even under constant water pressure. Questions? Contact us

1. Pre-dampen the substrate prior to installing MasterSeal 590.
2. Place MasterSeal 590 with minimum working, kneading, or rubbing.
3. Force MasterSeal 590 repair mortar into cracks or holes and hold in place (without twisting) until set is fully achieved.
4. Just prior to final hard set, 590 may be “shaved” with a trowel until flush with the surrounding surface. Always shave from the center out, in the direction of the bond line.
5. If the repair area is dry at the time of placement, keep substrate damp for 15 minutes minimum, using a fine spray misting of water, before and after placement.

1. To seal static cracks at the junction of floors and walls, rout or cut out the crack at least ¾” (19 mm) wide and deep, slightly undercutting if possible.
2. Flush away all loose debris, dust, and dirt with clean water.
3. Force 590 into the prepared crack with a round tool or margin trowel until a set is fully achieved and smooth out to form a cove at wall-to-floor junctions.
4. Keep damp for at least 15 minutes.

1. To stop active water from running through concrete and masonry, cut out crack or hole to a minimum depth and width of ¾” (19 mm). Always square cut or undercut when possible; do not “V” cut.
2. Start at top and force 590 into crack. In areas of great pressure, do not place MasterSeal 590 into opening immediately. Hold 590 in hand or on trowel until a slight warming occurs. Then press MasterSeal 590 firmly into opening.
3. Do not remove trowel or hand pressure too soon so as to provide some confinement to MasterSeal 590 expansion during its set. Do not twist MasterSeal 590 during placement or disturb during set time (5 minutes).
4. After placement to stop the active water flow, carefully cut and “trowel shave” the patch level with the surrounding surface.

Masterseal Waterplug

590 Use and Install


Weight 50 lbs
Dimensions 15 × 15 × 18 in