C-Cure MultiSet 917 Polymer-Modified Thinset Mortar Guide
C-Cure MultiSet 917 is a polymer-modified thinset mortar engineered for installing ceramic tile, porcelain tile, quarry tile, and many natural stone materials in residential and commercial applications. Its factory-blended formula combines Portland cement, graded sand, and dry polymer additives to deliver excellent bond strength, flexibility, and long-lasting performance without requiring separate liquid latex additives.
Designed for both interior and exterior installations, MultiSet 917 provides reliable adhesion to properly prepared substrates while helping improve freeze-thaw resistance, water resistance, and overall installation durability. It is an excellent choice for floors, walls, kitchens, bathrooms, backsplashes, and many other tile projects.
Why Choose C-Cure MultiSet 917?
- Premium polymer-modified thinset mortar.
- Excellent bond strength for ceramic, porcelain, and natural stone tile.
- Suitable for interior and exterior applications.
- Requires only clean water for mixing.
- Improved flexibility compared to standard dry-set mortars.
- Excellent freeze-thaw resistance.
- Strong water and impact resistance.
- Professional-grade performance for residential and commercial projects.
Recommended Applications
- Ceramic tile floors.
- Porcelain tile floors.
- Bathroom walls and floors.
- Kitchen floors and backsplashes.
- Natural stone installations.
- Interior wall tile.
- Exterior tile installations.
- Commercial flooring.
- Residential remodeling projects.
Compatible Substrates
When properly prepared, MultiSet 917 can be installed over a variety of approved substrates commonly used in tile installations.
- Concrete.
- Cured mortar beds.
- Cement backer board.
- Masonry.
- Brick.
- Properly bonded existing ceramic tile.
- Gypsum board on interior dry-area walls only.
Performance Benefits
The dry polymer additives blended into MultiSet 917 help improve bond strength, flexibility, impact resistance, and freeze-thaw durability compared to conventional dry-set mortars. This provides dependable long-term performance while simplifying installation by eliminating the need for separate liquid latex additives.
Where MultiSet 917 Performs Best
MultiSet 917 performs exceptionally well in kitchens, bathrooms, showers, laundry rooms, commercial buildings, retail stores, and many exterior tile installations where a high-performance polymer-modified mortar is recommended.
Surface Preparation
Proper surface preparation is essential for achieving maximum bond strength and long-lasting tile installations. All substrates should be structurally sound, clean, dry, and free of dust, dirt, grease, curing compounds, sealers, old adhesive residue, paint, or any contaminants that could interfere with adhesion.
Concrete, masonry, cement backer board, cured mortar beds, and other approved cementitious surfaces should be properly prepared before installation. Smooth concrete may require mechanical abrasion to improve bonding, while porous concrete can be lightly dampened before applying mortar. Do not leave standing water on the surface.
When installing over existing ceramic tile, verify that all tiles are firmly bonded and properly prepared to provide a suitable bonding surface.
Mixing Instructions
MultiSet 917 is designed to be mixed with clean, potable water only. Add the powder to water while mixing until a smooth, creamy consistency is achieved. Allow the mortar to slake for approximately 15 minutes, then remix without adding additional water.
For best performance, use a low-speed drill with a mixing paddle to help prevent excessive air from becoming trapped in the mortar. Once the mortar begins to harden, do not add additional water. Prepare a fresh batch instead.
Application
Using the flat side of the trowel, key the mortar firmly into the substrate before combing additional mortar with the appropriate notched trowel. Select a notch size that provides proper mortar coverage for the tile being installed.
Press tiles firmly into the fresh mortar while moving them perpendicular to the trowel ridges to collapse the mortar and achieve maximum coverage. Periodically remove a tile during installation to verify proper mortar transfer and coverage.
Large-format tile, heavily lugged tile, or irregular natural stone may require back buttering to help achieve full mortar coverage and proper support.
Curing
Protect freshly installed tile from heavy traffic, freezing temperatures, excessive heat, and moisture until the mortar has cured. Under normal jobsite conditions, light foot traffic may be permitted after the mortar has properly cured according to the manufacturer's recommendations before grouting begins.
Installation Tips for Best Results
- Use only clean, potable water when mixing.
- Mix each batch to the same consistency.
- Allow the mortar to slake before remixing.
- Never add water after the slake period.
- Select the correct trowel notch for the tile size.
- Check mortar coverage regularly during installation.
- Back butter large-format tile when needed.
- Protect fresh installations during the curing period.
Where MultiSet 917 Performs Best
- Porcelain tile installations.
- Ceramic tile floors.
- Natural stone flooring.
- Kitchen floors and backsplashes.
- Bathroom walls and floors.
- Commercial flooring.
- Retail stores.
- Hotels and hospitality projects.
- Interior remodeling.
- Exterior tile installations.
Professional Tip
The quality of a tile installation depends as much on proper mortar coverage as it does on the mortar itself. Always verify full mortar transfer by occasionally lifting a freshly installed tile. This simple step helps identify coverage issues before the installation is completed and contributes to a stronger, longer-lasting bond.
Cleanup
Clean tools, mixing equipment, and tile surfaces with water before the mortar cures. Once hardened, MultiSet 917 can only be removed by mechanical means. Prompt cleanup helps maintain a clean installation and reduces unnecessary finishing work.
Limitations
- Not intended for use as a medium-bed mortar.
- Not recommended for installation directly over wood, resilient flooring, vinyl, metal, glass, plastic, luan plywood, or other non-approved substrates.
- For glass tile or large-format porcelain tile, use the mortar recommended by the tile manufacturer.
- Protect freshly installed mortar from freezing temperatures during the curing period.
- MultiSet 917 is water resistant but is not a waterproofing membrane.
- Use a dedicated waterproofing membrane in showers, wet rooms, and other moisture-sensitive areas.
Technical Specifications
- Product Type: Polymer-modified thinset mortar.
- Mixing: Just add clean water.
- Available Colors: Gray and White.
- Packaging: 50 lb (22.7 kg) bag.
- Suitable for interior and exterior installations.
- Excellent bond strength and flexibility.
- Water and freeze-thaw resistant.
- Conforms to ANSI A118.1, A118.4, and A108.5 standards.
- Storage Life: Up to one year when stored in a cool, dry location in unopened packaging.
Safety Information
This product contains Portland cement and crystalline silica. Avoid breathing dust and prevent contact with eyes and skin. Wear appropriate eye protection, gloves, and a NIOSH-approved respirator when mixing or handling dry mortar. Keep out of reach of children and follow all safety instructions on the product packaging.
Warranty Information
C-Cure publishes installation recommendations and technical data based on laboratory testing and field experience. Product performance depends on proper substrate preparation, installation methods, environmental conditions, and jobsite practices. Always follow the latest manufacturer instructions and recognized tile industry standards for the best results.
Helpful Resources
Explore more guides on thinset, grout, caulking, waterproofing, and professional tile installation.
- C-Cure Frequently Asked Questions
- C-Cure MP Non-Sanded Grout 923 Guide
- C-Cure MP Sanded Grout 924 Guide
- C-Cure Setting Materials Guide
- How to Remove Silicone Caulking
- How to Clean Porcelain Tile Floors
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