Sika Thoroseal®-581

Contains cement, graded sand, and proprietary additives.

1 year when properly stored

Transport and store in unopened containers and keep in a clean, dry place protected from rain, dew, and humidity. Do not stack bags more than two pallets high. If dry onsite storage of bags is unavailable or if the project is located in a very wet, humid climate zone, then specify Sika Thoroseal®-581 packaged in 50 lb (22.7 kg) metal pails. 

Positive resistance to hydrostatic pressure

Negative resistance to hydrostatic pressure

Fungus resistance

Flame spread BS476:            Part 7:1971
Water Penetration                  ASTM E 514
Adhesion                                ASTM C 297
Sika Thoroseal®-581/CMU
Sika Thoroseal®-581/concrete
Stuccobase /Sika Thoroseal®-581
ASTM C 926 Stucco/Sika Thoroseal®-581
Shear bond                             ANSI 118.4 or similar
StuccoBase/Sika Thoroseal®-581/CMU
StuccoBase/Sika Thoroseal®-581/concrete

• 225 ft²/50 lbs (20.9 m²/22.7 kg) bag as a base coat at 1⁄16" (1.6 mm) dry-film thickness.
• 450 ft²/50 lbs (41.8 m²/22.7 kg) bag as a topcoat at 1⁄32" (0.8 mm) dry-film thickness.

Coverage will vary depending on surface texture and porosity.

• Sika Thoroseal®-581 must be modified with Sika Thoroseal® Acryl 60 to achieve the properties listed in the technical data section.
• Do not apply to substrates with active water leaks or moving cracks; patch all leaking static cracks and holes with SikaSet® Waterplug. Repair any other nonmoving cracks or voids with the appropriate Sika repair product and repair all moving cracks or voids with the appropriate sealant.
• Do not apply in rain or when rain is expected within 24 hours. Do not apply above 90 °F (32 °C) or below 40 °F (4 °C) or when temperatures are expected to fall below 40 °F (4 °C) within 24 hours. For hot and cold temperature applications, store Sika Thoroseal®-581, Sika Thoroseal® Acryl 60, and water at 50 °F (10 °C) to 70 °F (21 °C) before use.
• Hot substrates will affect working time and material strength.
• Variations between inside and outside temperatures may result in condensation on below-grade walls treated with Sika Thoroseal®-581. This can be alleviated by assuring that adequate ventilation exists.
• Windy, dry, or hot conditions may require rewetting of Sika Thoroseal®-581 during cure and the use of polyethylene barriers.
• Before specifying Sika Thoroseal®-581 for water retaining structures, conduct tests to determine water quality. Sika Thoroseal®-581 is not intended for continuous contact with acid or sulfate-containing water. Very soft water will have an adverse effect on Sika Thoroseal®-581.
• Service temperatures: immersion, up to 140 °F (60 °C); cleaning water, up to 200 °F (93 °C); dry air, up to 220 °F (104 °C).
• On all projects, it is recommended that a sample be prepared on-site and approved prior to the commencement of the work. The site sample should confirm the color, texture, and workmanship required until the job is finished and accepted. Retain the sample until final approval is secured.
• Allow Sika Thoroseal®-581 to cure for 7–10 days before immersion in water.
• Proper application is the responsibility of the user. Field visits by Sika personnel are for the purpose of making technical recommendations only and not for supervising or providing quality control on the jobsite.

1. Surface preparation is extremely important for proper adhesion. Substrates must be sound and free of dust, dirt, laitance, paints, oils, grease, curing compounds, or any other contaminants. Verify substrate has properly cured. Concrete should obtain 80% of design strength, typically achieved within 3–14 days. If efflorescence is present, mechanically remove it before proceeding. For extreme cases where this is not adequate, contact Technical Service.
2. Patch all holes and non-moving cracks before installation with the appropriate Sika product.
3. Relieve hydrostatic pressure in concrete block with weep holes.
4. Roughen or brush blast extremely smooth surfaces such as precast and cast-in-place concrete to ensure good mechanical adhesion of Sika Thoroseal®-581.
5. Completely saturate the substrate with water and allow the surface to dry before the application starts. A damp surface will prevent surface drag on the material, keep the substrate cool, and eliminate flash drying.

1. Mix Sika Thoroseal®-581 with a mixing liquid consisting of a blend of Sika Thoroseal® Acryl 60 diluted with water. The maximum dilution ratio is one part Sika Thoroseal® Acryl 60 (1½ quarts) to three parts water (4½ quarts). Approximately 6 quarts of mixing liquid is needed per 50 lbs of Sika Thoroseal®-581 powder. Up to 2 additional quarts of mixing liquid may be added when used as a rubbing compound.
2. For best results, mechanically mix Sika Thoroseal®-581 with a slow-speed drill and mixing paddle. Gradually add the powder to the mixing liquid while the drill is running.
3. When properly blended, Sika Thoroseal®-581 will have the lump-free consistency of smooth, heavy batter.
4. Allow the Sika Thoroseal®-581 and Sika Thoroseal® Acryl 60 mixture to rest undisturbed for a minimum of 10 minutes to fully wet out all the powder. Then mix the wet mixture and apply. A small amount of mixing liquid can be added to the mixture.
5. Pot life is 60–90 minutes at 70 °F (21 °C). At high temperatures and low relative humidity, pot life can be significantly less.

1. Apply Sika Thoroseal®-581 with a tampico brush or broom or equivalent stiff fiber brush or textured spray equipment. Spray applications of the first coat require back brushing or brooming to properly fill voids and achieve uniformity and optimum adhesion.
2. It is essential to work the first coat thoroughly into the substrate to completely fill and cover all voids, holes, and nonmoving cracks. Finish with a horizontal stroke for an even coat.
3. Allow to cure for 24 hours, then apply the second coat and finish with a vertical stroke. Above grade, the second coat can be replaced with a Sika high-build architectural coating to achieve better color uniformity.
4. On block or masonry walls, allow 5–7 days before applying a second coat to eliminate joint read-through or shadowing.

1. Sika Thoroseal®-581 shall be applied to CMU or concrete substrates in accordance with and prepared per Sika Thoroseal®-581 Technical Guide.
2. Mix Sika Thoroseal®-581 with a mixing liquid consisting of a blend of Sika Thoroseal® Acryl 60 diluted with water. The dilution ratio is one part Sika Thoroseal® Acryl 60 to three parts water.
3. Apply Sika Thoroseal®-581 at standard recommended thicknesses with a stiff fiber brush using a two-coat application. Allow the first coat to cure for 24 hours and then apply a second coat perpendicular to the first coat.
4. Allow Sika Thoroseal®-581 to cure and then directly apply Sika Stuccobase per manufacturer specifications or Portland Cement Plaster (Stucco) per ASTM C 926. Nominal thickness shall be 5/8".

Promptly clean hands and all tools with warm water while the product is still wet. Cured material may only be removed mechanically.