Stone
Restoration
Consolidation
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.
Filling
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.
Hardening : 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.
Strengthing : Stone strength is usually the result of an increase
in stone density brought about by binding processes.
Grinding : 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.
Polishing : 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 marble.
