Grout has stained lueders limestone

A. This is a common problem with some limestones. Certain grouts will bleed in. The first thing you need to do is make sure that it is dry. (I have seen some installations take months to dry.)

The best way to determine what the problem is is to take a hair dryer to the dark areas and see if you can dry them out. If not then it is stained. It is possible to remove the stain by using a poultice or Stain Sponge. I would first test a small area. You may have to have the grout removed before applying the sponge or poultice.

Both poultice powder and Stain Sponges can be purchased at www.StoneCareCentral.com. Download the Stone and Tile Care Guide for details on creating a Poultice to remove stains.

Dr. Fred

Chief Technical Director

BLEED
Staining caused by corrosive metals, oil-based putties, mastics, caulking, or sealing compounds

FIREPLACE
An opening on a hearth, served by a chimney flue, where an open fire may be laid

GROUT
A mixture of cement material and aggregate to which sufficient water is added to produce pouring consistency without segregation of the constituents

LIMESTONE
Sedimentary rock originated mostly by the decomposition of marine organism composed primarily of calcite or dolomite. The varieties of limestone used as dimension stone are usually well consolidated and exhibit a minimum of graining or bedding direction