Your Price: $159.00
Part Number:EOS-HB-5gal

HydroBlok (5 Gallon)

Coverage Rates (Note! rates may vary with porosity)

  • HydroBlok – You can expect one 5 gallon pail to cover 3 applications of 500 to 750 square feet of block.

HydroBlok is produced specifically for sealing heavyweight CMU (concrete masonry units). This is a user friendly product that will seal CMU structures under the most difficult conditions and leave the concrete blocks paint-able if desired. This spray on product is designed for new or old heavyweight CMU structures and will seal your blocks easily and effectively.

The wall must be clean and free of all paint, coatings, sealers, mold or algae. If the wall is a old damp wall it should be cleaned with EOS All Purpose Efflorescence Cleaner and brushed with a stiff bristle brush to remove all old contaminates. Rinse clean and allow to semi dry. If the wall has signs of white efflorescence apply a second application of EOS All Purpose Efflorescence Cleaner after the wall has been cleaned and dry. Do not apply water to the wall after the All Purpose Efflorescence Cleaner has been applied, just allow it to dry. All major cracks must be repaired at this time. Consult your EOS representative for advice on making repairs, call 1-800-259-8855.


All concrete must be clean, raw concrete, no paint or sealers. To remove algae spray down with a 50/50 mixture of Clorox and tap water. Deck brush and hose or mop down to rinse. Allow area to semi dry and apply HydroBlok with a inexpensive low-pressure (garden type) pump sprayer that you can use for both products.

Note! Always wet the block wall down with water before applying HydroBlok sealer. A good damp spray is adequate. Do not over saturate.

Application Instructions

  1. Fill your sprayer with HydroBlok and apply 3 wet applications to the walls spraying from the top down using a left right motion. Apply only enough product so as not to create run-off of the HydroBlok. A 12 inch sag in the sealer is the maximum desired. Use a left right motion for the first application, and an up down motion for the second application. Leave a shiny wet application of liquid sealer on the surface. HydroBlok will penetrate the concrete surface in 5 to 10 minutes leaving just a damp looking surface. A maximum of 30 to 45 minutes should be allowed between applications.
  2. Use a deck brush and a liberal amount of water 6 to 12 hours after the last application, vigorously brush to remove all residual sealer and purged contaminates from all surfaces that are to be painted or have other coatings or adhesives applied.
  3. Allow sealer 10 days to cure before applying another sealer, paint or topical treatment.

Note! If a wall render is to be applied wall must be free of all residual sealer by scrubbing with and deck brush and water 24 to 48 hours after last application of HydroBlok–OR–apply the HydroBlok in smaller sections using 3 consecutive applications. While the wall is still damp from the sealer apply the wall render. See wall render instruction included with your shipment.