Removing White Powdery Substance From Cinder Block
The element you cannot remember is basically is calcium salt calcium that is in all concrete. If there is excess moisture, it can be carried to the surface and deposited when the moisture evaporates. Since the block are probably not "cinder block" (very rare for the last 40 years) real cinder block could also contain many different salts since they were made from waste materials that are not economical now due to the availability of higher quality aggregates.
It is an alkali and can be neutralized by an acidic product (like vinegar) after the excess is brushed off. The good thing is that it lets you know where the excess moisture is coming out.
Last edited by concretemasonry; 04-12-2012 at 03:34 PM.