Painting on concrete

Last autumn I repainted the entrance to my garage using Ronseal "Diamond Hard" floor paint. The surface was cleaned down to smooth concrete with no oil contamination and seemed an ideal surface to paint. The paint went on well and I was very pleased with the job. However, a section has now begun to flake off very badly and I cannot understand why. Any advice would be gratefully received.

Moisture is the likely problem.

Concrete needs to be absolutely bone dry. You should rub back,mallow it to dry and start again. Stabiliser might help with adhesion.

Thanks for your advice, Chris. The concrete was absolutely dry before I painted it. Also, the paint is water based so I am not convinced that this was the problem. A stabiliser might be a good idea, though, and I was wondering if an acid etch would be useful and would welcome advice on that.