NPW Negative Pressure Waterproofer

basementNPW Negative Pressure Waterproofer is a non-flammable, non-toxic, non-acid sealer that strengthens and internally waterproofs cementious materials. NPW is a chemical hardener, densifier, and soluble chloride reducer. NPW reduces vapor emissions for application of surface coatings such as polyurea coatings, epoxy coatings, urethane coatings, as well as carpet, floor tile, sheet vinyl and hardwood flooring materials.

In conditions where salt air and humidity attack the concrete, causing oxidation of the reinforcing steel, NPW has proved to halt such corrosion activity. When NPW is applied to concrete exposed to such conditions, exfoliation or expulsion of the chlorides takes place.

NPW reacts with free alkali in the concrete forming a silica hydrogel that fills the capillaries within the matrix. This hydrogel waterproofs and seals the surface after all materials harmful to the concrete are removed. This process could take up to thirty days or longer, depending on the chloride and acidic residual concentration within the capillaries. NPW may be applied as a cure-and-seal, as soon as the concrete bleed water flashes off. When properly installed, application of this sealer reduces wait time to apply flooring or coatings to an average of 5 days. ALWAYS check surface for moisture content before applying coatings, or flooring.

NPW is a proprietary formulation of hybrid silicates containing a patented surfactant. It achieves an excellent crystalline matrix and deep penetration.

Uses: Interior/exterior, above and below grade applications for Concrete • Precast • Block • Mortar • Stone

CLEAR • No. 808301-1 • ONE U.S.GALLON / 3.79L
CLEAR • No. 808301-5 • FIVE U.S.GALLONS /18.92L

NPW has a wide variety of uses, download the Tech Data Sheet in Technical Information tab below or contact us for more information on specific uses.

  • Blocks and reduces vapor emissions through concrete but leaves concrete breathable.
  • Purges soluble chlorides and prevents re-entry.
  • Penetration depends on density of concrete and masonry substrate.
  • Does not alter bondability of concrete.
  • Environmentally friendly, water-based, non-combustible. No flammable solvents.
  • Contains a non-acid penetrating agent — resists many acids, oils, greases and salts.

NPW will reduce water vapor emissions on surfaces and reduce or block migration of radon gas. NPW is excellent on concrete, precast, block, brick, mortar, and stone. NPW IS NOT MEANT FOR APPLICATION OVER TILE, EVEN POROUS TILE, AND SHOULD NOT BE USED IN ANY TOPICAL APPLICATION OVER TILE! NPW is an excellent moisture reducer prior to application of adhesives, coatings, tile, and sheet vinyl. NPW, when applied as a cure-and-seal immediately after concrete bleed water flashes off, will reduce coatings and adhesive “green window” from 28 days down to an average of 5. NPW will block MVT (moisture vapor transfer) up to 20 Ibs and Hydrostatic Pressure up to 15 psi.

  • Ensure surface is free of dirt, debris, oils, grease, old adhesives or coatings, and standing water.†  Shake well before using. Do not dilute or alter.
  • Apply NPW with a low pressure pump type sprayer, with a fan tip.
  • Horizontal Surfaces: apply in a left-to-right pattern overlapping spray pattern 50%. After first application soaks in, immediately apply a second application in an up-and-down pattern overlapping 50%. Avoid over-application or ponding. Excess un-reacted product will leave white crystals on the surface so brush or broom excess to dry areas.
  • Vertical surfaces: apply from top-to-bottom to the point of refusal. Apply sealer in two even coats. After first coat has soaked in immediately apply a second coat.
  • On horizontal or vertical surfaces, areas that absorb sealer more quickly will require additional coats.
  • On all surfaces after second coat has soaked in, remove any  excess material from surface, and, spray entire treated area with a very light mist of clean water.
  • Keep dry and allow surface to cure minimum 12 hours, for applications with high moisture transfer allow surface to cure 72 hours.
Rough slab finish 75-200 sq. ft/gallon
Dense and smooth finish: 150-200 sq. ft/gallon
Protect all glass and glazed surfaces from overspray.
  • NPW can be mildly irritating to skin and eyes, take precautions while using this product.
  • Protect all adjacent surfaces from overspray.
  • Rinse all surrounding plant life thoroughly after application.
  • NPW is a professional product, and is very effective when applied SPECIFICALLY AS DIRECTED.

Sanding or removal of paint containing lead may be hazardous. Call 1-800 424-LEAD for details.

KEEP OUT OF REACH OF CHILDREN. Manufacturer’s responsibility is limited to the purchase price of this product.
Use the following link to download/view the Adobe Acrobat PDF for
Use the following link to download/view the Adobe Acrobat PDF for