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KILZ® Waterproof Sealant is a versatile, low-odor, mold and mildew-resistant 100% Silicone sealant offering permanent flexibility in a finished seal that will not crack or shrink. Ideal for areas that are prone to water exposure, this high-performing durable formula creates a 100% waterproof finish that is water-ready in 10 minutes. Mechanical stress and strong water pressure will disturb seal of uncured material and impact performance. This product is not paintable, and is non-corrosive towards metals such as chrome, bronze, nickel, etc.

Two colors available S20 Clear and S21 White.

Available in 10.1 oz

Please check availability before visiting your local retailer

  • Ratings & Reviews
  • Preparation, Application & Clean-Up
  • Warranty / Warnings
  • Product Specifications


The surface must be clean, free of dust, chalk, oil, grease and all other loose materials.

Use on properly prepared interior or exterior surfaces to seal connection joints such as:

  • Kitchens
  • Bathrooms
  • Showers
  • Basements

Ideal for commonly found surfaces such as:

  • Most metals and woods
  • Glass
  • Drywalls
  • Plaster
  • Granite
  • Cultured marble
  • Ceramic and porcelain tile
  • Natural stone
  • Cement board
  • Composites
  • Fiberglass
  • Aluminum
  • Other painted surfaces

Apply when sealant, surface, and air temperatures are above 40°F.



  • Using proper safety precautions, cut the spout or tip of the cartridge at a 45° angle to the desired bead size and puncture the foil film. Load the cartridge into a caulk gun and squeeze the bead of caulk into the desired location. If the crack depth exceeds 3/8", use a backer rod material. Smooth the bead with a caulking tool and allow 10 minutes for caulk skin to form before painting with a brush/roller, or use a paint sprayer immediately. When finished be sure to remove and clean up all excess caulking material, and reseal cartridge for storage and reuse.
  • Application Temperature: 40°F – 100°F.

Dry Time at 77°F, 50% RH

Dry Time: @ 77°F, 50% RH
Longer dry time required in cooler temperatures and in higher humidity.​

  • Full Cure: 1 week
  • Water-Ready: 10 minutes 
  • Shelf Life: 12 months, unopened and stored in a dry place between 40°F and 80°F


  • Clean all tools and equipment with warm soapy water and rinse with warm clean water.

Masterchem Industries LLC warrants to you, the original residential consumer purchaser, that this product will provide a waterproof finish and hide hairline cracks existing at the time of original product application for so long as you reside in your home. THIS WARRANTY IS NOT VALID WHEN THE PRODUCT IS NOT PROPERLY APPLIED TO A PROPERLY PREPARED SURFACE OR CARED FOR IN ACCORDANCE WITH THE LABEL DIRECTIONS.  THIS WARRANTY EXCLUDES WATER INTRUSION DUE TO STRUCTURAL DEFECTS AND/OR CAULK FAILURE.  Color fading and chalking will occur naturally over time.  This warranty is not transferable. If this product is found not to perform as specified on the label during the warranty period, Masterchem Industries LLC will, at its option and upon presentation of proof-of-purchase (the original receipt), either furnish an equivalent amount of new product or refund the original purchase price of this product to you. This warranty excludes (1) labor and costs of labor for the application or removal of any product, and (2) any incidental or consequential damages, whether based on breach of express or implied warranty, negligence, strict liability or any other legal theory. Some states do not allow the exclusion or limitation of incidental or consequential damages, so the above limitation or exclusion may not apply to you. This warranty gives you specific legal rights and you may also have other rights, which vary from state to state. Note to residents of the State of New Jersey: The provisions of this warranty, including its limitations, are intended to apply to the fullest extent permitted by the laws of the State of New Jersey. For warranty service, call: 1-866-977-3711, or email: Masterchem Industries LLC reserves the right to inspect any and all application of the product prior to processing your claim made under this warranty.



  • Protect from freezing.
  • Not suitable for continuous exposure to water.
  • Not suitable for PE, PP, PC, PMMA, PTFE, soft plastics, neoprene and bituminous substrates.
  • Exterior applications only when applied in dry weather, and applied caulk must stay dry for at least 5 hours after application.
  • For best results, apply at temperatures between 40°F – 90°F.
  • Eye protection is recommended. Avoid contact with eyes. May cause eye, nose and throat irritation.
  • Avoid breathing of dust, vapors or spray mist. Open windows and doors or use other means to ensure fresh air entry during application and drying.
  • If vapor/mist levels cause eye watering, headache, or dizziness, wear an appropriate, properly fitted respirator (NIOSH / MSHA TC 23C or equivalent).
  • Reseal container for storage and reuse.
  • Wash hands thoroughly after handling and before smoking and eating.
  • Shelf life under normal conditions is 12 months unopened.

CAUTION IRRITANT MAY IRRITATE EYES, SKIN, AND RESPIRATORY TRACT. CONTAINS LIMESTONE, CRYSTALLINE SILICA AND TITANIUM DIOXIDE. Do not breathe fumes. Do not get in eyes, on skin or on clothing. Do not swallow. Handle with care. Use only in well-ventilated area or wear a respirator. Wear protective clothing including safety glasses and gloves. Wash thoroughly after handling. Store in a cool dry area. Do not reuse container.
FIRST AID TREATMENT: If in eyes or on skin, rinse with water for at least 15 minutes. If on clothes, remove clothing. If inhaled, move person to fresh air. If swallowed, call a Poison Control Center or doctor immediately. Do not induce vomiting.


  • Product Number


  • Packaging

    10.1 oz.

  • Color S20


  • Color S21


  • Base Polymer

    100% Silicone

  • Density

    8.6 lb/gal

  • Joint Movement


  • VOC

    < 40 g/L

  • Flash Point

    > 200°F

  • Coverage

    55 linear ft. at a 3/16" bead size

  • Meets or exceeds

    ASTM C-920 Type S, Grade NS, Class 25 NS ASTM C-834 Type OP Grade -18C