Natural stones age and weather with time. Binding of loose particulate is a desirable process when it is necessary to arrest degenerative processes. Limestone and sandstone are both excellent candidates for binding processes which replace lost minerals which hold the stone together.
There are many types of potential binding agents including various polymers (acrylic, urethane, silicones, polyesters etc.) as well as mineral based silicates available. Caution must be exercised in the evaluation of a potential binding agent as the physical compatibility of the binder with the stone is critical.
Binding agents and processes are underutilized today primarily due to lack of historical data regarding suitability and lack of knowledgeable restoration specialists.
It is sometimes desirable to fill cavities in natural stone in order to decrease maintenance costs, avoid mechanical trapping of soils and contaminants or for design considerations.
Some stones may be chemically hardened in order to resist abrasion more effectively. Limestone may be hardened by a number of chemical processes including silica impregnators, silico-fluoride treatments, or binding processes may give a hardening effect.
Stone strength is usually the result of an increase in stone density brought about by binding processes.
Grinding is the historical method of restoring a worn and weathered stone surface to it’s original cosmetic condition. It is also the pre-conditioning stage for polishing with oxides. Silicon carbide and diamonds are the most common abrasives used.
This is usually a mechanical abrasion process sometimes coupled with chemical action. A typical polishing compound is composed of aluminum and/or tin oxides and water. Oxalic acid is used as an additive for polishing some marbles.
Be sure to check back often for more tips and tricks.