Proline Decorative Concrete Systems Dura-Color Hardener CH649 60 lb Saltillo Tile Slate Dry-Shake. Proline Dura Color Hardener is a colored dry-shake hardener that is broadcast by hand over the top of freshly placed concrete and worked in with a wood float to form a dense, colored concrete ‘skin’ on the slab surface. Dry-shake color hardener is best applied to a concrete slab containing no more than a 4 inch slump and between a 5 and 6 sack per cubic yard cement content. This product is compatible with most admixtures, but avoid those containing calcium chloride. Apply PROLINEDURA COLOR HARDENER shortly after screening and floating the new concrete just as the bleed water is coming to the slab surface. It should be broadcast by hand as uniformly as possible and then worked in with a wood float. Start with the edges first then work in toward the middle when broadcasting and floating. Most colors will goon with two shakes, or coats, followed by touch up but lighter colors may require three shakes. If the surface is to be textured, then a light troweling is recommended. Over-troweling will discolor the concrete. For a textured ‘antique’ look, a light hardener color should be paired with a darker Proline Dura Antique Release and Proline texture Mats for stamping. It is always recommended that a representative job site sample be done to test the look of the color and texture combinations.