Best Method for Coloring Step Faces

Applying a paste made with color hardener is an effective, easy way
to color step faces. Using the same hardener that was applied to the
flatwork portions of the project helps to ensure color uniformity.

Question:
When stamping and coloring a set of steps, how do I get the risers, or step faces, to match the treads and adjoining patio surfaces?

Answer:
This can be accomplished with dry-shake color hardener or integral color, but using color hardener often achieves the best results. When using integral color, timing is everything. No matter how smooth the surfaces of your forms, some toweling will need to be done to the faces once the forms are removed. This means removing the forms while the concrete is still wet enough to take a trowel and be imprinted, but not too wet so the stairs slump and lose shape. This can be a tricky proposition, depending on the number and size of the steps.

When using the color hardener method, you can pull forms the same day (with a much longer set time if desired) or after many days. When you’re ready to color the step faces, you mix the hardener with a concrete polymer glue – acrylic or polyvinyl acetate (PVA) work best – to create a paste that you apply with a trowel as if icing a cake. By roughening the step faces a little after removing the forms (a light broom finish works well) you provide a better surface for the color hardener paste to grab onto.

Note that with both methods, knowing the best time to imprint the concrete is important to achieving good results, so experience is critical. The water-cement ratio of the concrete is also important. Do not add water to the step faces when using integral color, as this will dramatically lighten the color. When using the color hardener method, strive to make the color hardener paste the same consistency and slump as the concrete was when the hardener was applied to the flat surfaces. This will ensure a more uniform color match to the flatwork areas. Be careful of using color hardener paste for step faces when integral color has been used on the rest of the project. There are many variables to control, so achieving a good color match becomes very difficult.