Remocal of water based concrete stain

[RobertN]

We stained our concrete patio with water based stain a couple years ago. It needs to be redone. We would like to redo it with an acid based stain.

How can I remove the old stain? It is flaking in some spots. I tried a pressure washer, taking care not to remove the cream layer of the concrete. That is hard to do, and still get the other stuff off... It took over an hour to do a 5x2' section; I have almost 700sqft to do.

The acid stain pamphlet says not to use acid to wash the concrete; the acid stain will not take if this has been done.

Any idea's?

 

[beenthere]

What is the 'cream' layer of the concrete? Referring to a color layer, or referring to the trowelled top finishing layer?

Does the stain penetrate this top layer?

Is sandblasting a possibility?

Wonder what the 'acid stain' people say about removing the old stain, and why acid to remove would present a problem?

The acid stain looks interesting, and am thinking about it as a potential for using on outdoor concrete.

 

[RobertN]

The "cream" layer is that top layer that is troweled when the concrete is poured. The acid stain would penetrate that, which works better than the water based stain which does not.

If the concrete is cleaned with an acid, then it also affects to properties of the concrete(I do not know the details). Once that happens, an acid based stain will not work properly.

Sandblasting is possible, but it will affect that top smooth concrete layer.

this is the product the local company carries Brickform

 

[Ozarker]

I have never removed stain from concrete before but if I needed to, I think I would try Citrus-Strip and then follow that with a bleach/water solution for a final cleaning.