Release Powder Causes Streaking

Applying release powder with a heavy hand or on a slab that is too
wet can result in streaking.

Question:
Why did I get black streaks on the surface of this stamped concrete slab after removing the residual release powder, and how do I get rid of them?

Answer:
As the photo shows, the streaks of black release powder appear to be oriented in the direction in which the powder was thrown. This often occurs when too much material is applied at one time or on a slab that is too wet. Hard, clumpy release powder can also contribute to streaking. Always roll or “fluff” the powder in its container before application to break up any clumps. Also take care to cast the powder evenly across the slab rather than downward.

Another consideration is proper dispersion of the pigment in the release powder. If the material is not mixed properly at the manufacturing plant, streaking like this can occur. Always retain the batch number or a sample of the material so the manufacturer can run a test to verify if this was the cause of the problem.

Removing these types of blemishes can be difficult. You can try lifting the streaks of powder by scrubbing with a dilute acid solution. Another option is to disguise them by applying a stain or tint.