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  • Overview
  • Specs
  • Coverage Rate
  • Application

Blok-lok Silane Siloxane Water Repellent For Superior Wall Protection

Rainguard Blok-lok™ Silane Siloxane Penetrating Water Repellent Sealer sets an industry standard for superior vertical surface moisture protection. Used on new construction, infrastructure and remodel projects throughtout the US and Worldwide, it’s tested to stop a 98 mph wind driven rain coming through a treated concrete, brick, block or stucco wall surface without changing the look or texture of the surface.

Made from the best water repellent chemicals in the construction market, Blok-lok is a blend of silanes and siloxanes trusted by architects, engineers and building owners looking for long lasting protection. What makes Blok-lok different? A proprietary ingredient called Micro-Lok™. This additive ensures a long lasting mechanical bond and creates a hydrophobic barrier not affected by weathering, salt, dirt, freezing temperatures, UV light and wind-driven rain.

Blok-lok is a penetrating sealer invisible after application as it penetrates completely below the surface.  It protects against damage from water, salt and freeze – thaw cycling that can cause cracks in a surface. Available in ready-to-use and money saving concentrate and super concentrate options.

Where is Blok-lok used?

  • Construction & Remodel Projects:   Exterior building|screen|retaining|parapet walls, bridge abutments, stadiums, curing compound vertical concrete
  • Homeowner projects:  Exterior brick|stucco walls, chimeys, fences
  • Non-traditional applications:  Clay tile roofs, Clay|concrete flower pots, indoor bathroom tile mortar grout sealing,  outdoor unpainted wood furniture, indoor fireplaces

Why Blok-lok Water Repellent Sealer?

  • Labor and material water repellent warranty available for 5 years
  • Easy to use Concentrates available that saves money, time and easier on the environment!
  • ASTM tested for superior performance in stopping water and salt damage
  • 100% Eco-friendly: low VOC
  • Excellent mold and mildew inhibitor
  • Does not alter surface appearance & UV resistant – will not yellow>
  • Overspray of Bloklok during application will not harm glass or other building surfaces
  • Can be used on surfaces with admixtures such as Dry-Block
  • Nationally specified by architects in CSI sections 04220, 07185, 07190
  • Comparison Chart of Concrete Sealers by


Color Clear, No change in appearance or surface texture
Sheen/Gloss Level None
Dry To Re-Coat 30-60 Minutes
#Coats Recommended 1 (2 coats if especially porous)
Application method Low pressure hand pump or airless sprayer
Where Can it be Used All vertical unpainted, porous surfaces
Apply to New Concrete 48 hours
Low Application Temperature 35F|1.7C Surface & Air
 Base  Water
VOC Content <15 g/L
Use on Material Concrete, brick, masonry, stucco, block. natural stone, EIFS, wood
Warranty Available 5 years material/labor standard –  download warranty application to register, see DOCUMENTS tab above
Full Chemical Cure 5 -7 days for full product performance

Leed 4.2 (1) point credit available Meets LEED and SQAMD low VOC requirements
ASTM D-1653 Water Vapor Transmission Rate 100% Vapor Permeable
ASTM E-514 Wind Driven Rain passed 98 mph/160 kph (98.7% leak reduction)
ASTM C67-87 Water Repellency 97% Effective
ASTM E84 Surface Burning Flame spread 0, smoke developed 0
NCHRP No 244 Series IV Salt Pounding 87% reduction
ASTM G-53 Weathering 2500 hours – no change
MPI #34 Master Painters Institute
CMU Precision Block 60-70
CMU Split Face 50-70
CMU Scored/Flute 65-80
CMU Lightweight 40-55
Clay Brick 125-150
Concrete (Dense Masonry) 125-150
Adobe Brick/Natural Stone 70-90
Stucco 100-150
Wood 150-200
Concrete Curing 250
*Extremely porous surfaces  May require 2nd application
*Textured surfaces  Decreases coverage rates


Temperature (surface|air) 35F to 90F (1.7C to 35C) and at least 5F above dew point
Moisture of substrate Less than 15%
Humidity Less than 90%
Rain No rain 48 hrs prior to, 12 hrs after application
Cure time for newly poured concrete Apply 48 hrs after pour
Application method Use low pressure hand pump or garden sprayer


CR-0607 6 oz 1 Gal Empty 6oz into 1 gal container, fill with water, shake (19 parts water to 1 part Blok-lok)
CR-0608 32 oz 5 Gal Empty 32oz into 5 gal pail, fill with water, stir (19 parts water to 1 part Blok-lok)
CR-0601 1 Gal 10 Gal Measure concentrate needed, mix with water, stir (use 9 parts water to 1 part Blok-lok)
CR-0605 5 Gal 50 Gal Measure concentrate needed, mix with water, stir (use 9 parts water to 1 part Blok-lok)
CR-0616PK 32 oz 30 Gal Case of 6 quarts CR-0608 see that sku for instructions
CR-0617K 1 Gal 40 Gal Case of 4 gallons CR-0601 see that sku for instructions

1. Blok-lok should be applied using low-pressure airless or hand pump spray equipment
2. Do not atomize material (don’t want product to spray as a mist) as it will negatively impact product performance. For power sprayers, use large tip size of at least .035 to .051. For hand pump sprayers, turn spray nozzle at end of the spray wand so product flows out more like a steady stream and keep pressure up to amke sre enough material is coming out. Spray head should be held 8 to 12 inches from the surface so material floods down the wall at least 6-12 inches below the point of application.  For horizontal applications, apply until surface is completely saturated and pooling occurs.  Do not need to backroll or sweep off excess if absorption takes place within 1-2 minutes. For quickest application rate and to ensure a completely saturated surface suggest on powered spray equipment, remove the spray tip and on hand pump sprayers, remove the wand/tip. Product will flow very quickly, in a steady stream and completely eliminate atomizing.
3. Avoid application in windy weather.
4. Trigger gun off at the end of each pass to avoid using excessive materials. Stop all applications only at corners, joints, seams, or edges.
5. Multiple coats may be applied, whiting or yellowing will not occur.  A second coat is best applied “wet on wet” which means apply when first coat is damp but not yet dry.  Use same flood coat procedure.

1. All surfaces to be coated should be clean of any dirt and grime, efflorescence, lime run, form oils and release agents, grease, mud, excess mortar, and mold and mildew, etc.
2. All cracks should be pointed or caulked. All voids, bee holes, masonry surface defects and openings such as conduits, pipes, drains, door frames, vents, air conditioner openings, electrical openings, control joints, or any dissimilar materials should be repaired using urethane or other approved patching.

Store materials in a well-protected area between 45° and 90°F. Avoid freezing temperatures, direct sunlight, and moisture. Keep away from heat sources.