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Stone Mason® Flex Concrete Filler

Product Description
Installation and
Technical Literature
Application Tips
and Instructions

Water-based, easy-to-use Stone Mason® Flex Concrete Filler is designed to fill horizontal cracks and expansion joints in concrete or masonry surfaces where joint movement is anticipated.


  • Ready-to-use and self-leveling
  • Dries gray to match most existing concrete
  • Suitable for both exterior and interior use


  • Each 946ml (1 quart) bottle will fill 23m (76') based on a 6mm by 6mm (1/4" by 1/4") crack

SDS Sheets

Stone Mason® Flex Concrete Filler SDS Sheet Download PDF      

Surface Preparation

Thoroughly clean surface area free from all dust, dirt or other loose materials, using a wire brush if necessary. Stone Mason® All Purpose Concrete Cleaner is recommended to remove oil and grease contamination. Surface area must be dry, however, if the temperature is 27°C (80°F) or above, lightly dampen the area with water mist before applying.


Mix by inverting, shaking and/or squeezing Concrete Flex bottle before opening to ensure a uniform mixture.


Each 946 ml (1 quart) bottle will fill 23 m (76') based on a 6 mm by 6 mm (1/4" by 1/4") crack.


  1. Remove the protective cap and cut the tip of the nozzle to desired size.
  2. For deep cracks add fine sand to approximately 6 mm (1/4") from surface. Complete by filling with Concrete Flex.
  3. For narrow cracks it may be necessary to thin material by setting the bottle in hot water for 10 minutes before use. Press or trowel sealant into crack.

Drying Time

Dependent on wind, temperature and relative humidity. Under normal conditions at 21°C (70°F) and 55% RH, allow 7 to 10 days for complete cure. The surface is typically dry-to-touch within 1 hour following application.


Use soap and water while compound is still fresh.


  • Maximum crack depth should not exceed 6 mm (1/4"). Maximum crack width should not exceed 51 mm (2").
  • Not recommended for use in heavy vehicular traffic areas.
  • Do not apply if rain is expected within 24 hours or if temperature is expected to drop bellow 10°C (50°F). Do not apply to frozen or frosted substrates.
  • Store at a temperature above 5°C (40°F) and keep container tightly sealed.


Avoid contact with skin and eyes. In case of eye contact, flush thoroughly with water for 15 minutes and get immediate medical attention. KEEP OUT OF REACH OF CHILDREN. KEEP FROM FREEZING.

The consumer shall satisfy themselves of the suitability of this product for the intended purpose. Weather, applicator's skill and surface conditions are beyond manufacturer's control. We, therefore, limit our liability to replacement of defective material only, within one year of proof of purchase.