TFC CoolCrete Stain offers a unique way to enhance concrete surfaces by introducing rich, permanent colour through a chemical reaction with the concrete itself. Rather than simply lying on top, the stain penetrates unsealed, porous concrete and reacts with free lime (calcium hydroxide) in the concrete mix to form insoluble metallic salts — this “rusting” effect creates durable, integral colour that won’t peel or wear off.
How it works & key features
- Acid based, water carried:Â the acidic component opens up the concrete surface, allowing penetration; the water then helps the reaction to develop.
- Permanent colour: the reaction produces insoluble colour inside the concrete, meaning it won’t merely be surface coating but will last as part of the concrete.
- Works on both new and old concrete:Â provided the concrete is unsealed and porous, and contains enough free lime.
Factors that affect the final look
- The age of the concrete: newer concrete tends to have more free lime, so richer colour development.
- Moisture content and environmental conditions during and after application: cooler, damper conditions tend to allow deeper penetration and more intense color development. Excess moisture, however, can cause blotches or issues.
- The type of concrete finish (floated vs trowelled vs power floated) affects density and surface lime content; less dense surfaces tend to develop more intense colour.
- The type of aggregate (especially non-reactive/siliceous aggregates) and any cement additives or accelerators can affect both colour strength and uniformity.
