Maybe they never densified. Maybe effervescence where moisture wicking up through concrete and the minerals remain on the surface from the moisture. I would try scrubbing and extraction, densifier application, burnish off. But hard to really know without knowing the contractors steps they did. If they put a guard on at the end. If you have more information that would be good.

On Sep 6, 2014, at 12:15 AM, Stephen Webb <stephen@newlifemarblerestoration.com> wrote:

> A contractor friend had a clients concrete polished (by someone else) and she is having trouble with dust, saying it doesn't swifer off. any suggestions for a treatment? Thanks
>
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