Materials variously treated with sodium silicate were studied until enough
information was obtained to find a way to solve the problems that have
prevented sodium silicate from being the used as a fire retardant. These
problems are: 1) water solubility (miscible with water), which results in
extensive leaching when exposed to water, 2) cracking, chipping and
peeling of treated surfaces, and 3) surface granulation. During flame
tests it was discovered that sodium silicate formed a foam-like material,
and this material was found to have become water insoluble, yet its
elemental composition had remained virtually identical to that of the
unmodified sodium silicate. This investigator proposes that under the
influence of heat and dehydration, sodium silicate undergoes a
polymerization process resulting in particles sizes too large to dissolve
in water, and then developed a mechanism to explain how the process could
occur. The temperature and moisture conditions in treated samples were
then manipulated to cause the polymerization process to occur while
protecting the wood from damage. Thus samples were prepared that were
both water insoluble, and possessed effective fire retardant properties.
These samples also proved to be stronger than untreated wood, thus
providing an improved product that was fire retardant and moisture
resistant. Since aqueous sodium silicate can be combined with other
inorganic fire retardants, this technique is a potential method for
making any inorganic fire retardants moisture resistant. This represents
a potential breakthrough in fire retardants that has been sought for
approximately 100 years. In addition, sodium silicate treated samples
were made moisture resistant by the application of a micro-thin layer of
silicon monoxide to the surface of samples. This technique, also never
tried before, represents a second method for providing moisture
resistant, fire retardant substances.