ASTM C-309

Standard Specifications for Liquid Membrane Forming Curing Compounds and Curing and Sealing Compounds.

The most common concrete curing specification in use today. States that the compound must form a membrane and have moisture retention properties equalling 0.55 Kg/M² in 72 hours when applied at 200 Ft.² per gallon. Compounds are classified according to type and class.

TYPE refers to color only

• Type 1: clear
• Type ID: clear with fugitive dye
• Type II: white pigmented

Class refers to the kind of resin solids used in the compound

• Class A unrestricted: This is generally accepted as meaning nonresins such as waxes.
• Class B restricted: Restricted to all resin materials, namely acrylics, acrylic blends, epoxies and all other blends.

If a curing compound is said to be Class B, it is also considered to be an A.