GHOSTSHIELD SILA-TEK 3500: Our cost-effective, all-in-one primer, densifier and sodium-based hardener. Available in an industry leading, concentrated formula that mixes with water to makes 5 gallons. CONCENTRATED & COST-EFFECTIVE: This cost-effective sodium-based densifier is often used before polishing concrete. It also works well as a primer to strengthen and harden concrete and increase the performance of a sealer. When used as a primer it increases adhesion of a top coat sealer up to 25%. USE PRIOR TO POLISHING CONCRETE: Easily applied with a sprayer, roller or brush, the 3500 can be used on a variety of poured concrete substrates. Can be used indoors and outdoors but a sealer is recommended to be used in conjunction if concrete will not be polished. A popular choice to prime and harden new and old concrete. *Not recommended for: Bricks, Concrete Blocks / Cinderblocks, Polished or Extremely Smooth Concrete DRIES CLEAR & NATURAL: Provides a flat, natural finish. Treated concrete will not change in appearance, color or texture unless concrete is polished. This dual-function product is mixed with water prior to application and dries within a few hours of application. Once a densifier has been used, you do not need to retreat concrete in the future. Often used prior to polishing concrete to achieve a glossy finish. Color: Clear/ Natural.