General Poultice Method
The General Poultice Method is a special cleaning procedure for removal of deep-seated stains, grit and grime which regular cleaning does not remove. The General Poultice Method is the process of combining the appropriate cleaning agent, often a liquid additive, with a powdered poultice which usually looks like common household cooking flour. When stirred, the mixture forms a pasta-holding medium, that concentrates its effort over a period of time by drawing the stain out of the marble and into the poultice.
The cleaning agent is the moat important ingredient in poultice. Be sure to identify what has caused the stain so that an appropriate additive is mixed with the poultice, as the liquid additive is the actual cleaning agent. For example, consider an organic stain such as coffee or tea. If the stone has been installed for several years and a whitening bleach is used as the additive, apply the poultice mixture cautiously since the General Poultice Method can potentially make your marble look cleaner and brighter than the rest of your floor, Perhaps poultice mixed with water instead of bleach might be a better choice in this scenario unless one understands that a deep cleaning of the entire floor may become necessary to make the marble look uniform in color again.
Poultice can be mixed with various liquid additives, (i.e., water, a neutral cleaner, household laundry bleach, acetone and various others*), to form a paste the consistency of oatmeal. For estimating purposes, figure a usage rate of one pound of paste per square foot surface. Apply the poultice paste to the marble with a wood or plastic spatula to avoid the possibility of scratching the surface and to ensure a uniform thickness of approximately 1/2”. Tape a plastic sheet over the area to retain moisture and allow to set 24-48 hours. Always apply the areas surrounding the stain to prevent the stain from being forced into clean stone. Remove the poultice with a wood or plastic spatula and rinse with clean water, blot excess and allow to dry.
Several applications may be necessary depending upon the specific stain. The poultice may be applied to polished, honed or flamed/textured stone as well as polished terrazzo.
* Refer to a specific type of stain below for an appropriate additive.