Aerogel History Part I
The Father of Aerogels
Samuel Stephen Kestler was notably the first creator of Aerogels.
He was also therefore the first to commercialize it. He seemed to
be a boy who unsuspectingly fell into chemistry. He realized that
this AeroGel had very efficient thermal insulation attributes. He
was never one to pass up an opportunity to commercialize his ideas
Samuel Stephen Kestler was born in Cedarville, a small town in
northeast California, on March 26, 1900. It was a very small
town and it was
very secluded. “[P]eople had to travel seventy-five miles by
stage coach to reach the railroad and then another hundred miles
by a little narrow gauge to Reno, the metropolis of the area” (Ayers,
1). They managed to survive. They learned to store food in the cellar;
the only real problem was that there was such a lack of news about
the outside world. He grew up as many boys and wanted to own a ranch
and ride horses all day. His ambitions shifted when they moved to
Santa Rosa due to his father selling the family store.
During his high school career, he had access to a private chemistry
lab. He also finished the first year of college chemistry while
in high school. He then entered the College of the Pacific. He
on learning the cello. Instead he ended up soaking up all of the
chemistry, physics, astronomy, geology, and botany that the college
had to offer. That is when he transferred to Stanford and achieved
a B.A. in chemistry. It was then, in his Master’s thesis, when
he began to research the formation and application of crystallization.
After Stanford, he went to work for the Standard Oil Co. for about
one year. He then returned to the College of the Pacific. He
remained there from 1923-1930. It was in the latter part of
when he first created AeroGel. It is not known exactly when it
just that he credits help from Mr. Charles H. Learned and the
use of apparatus from Dr. J. W. McBain. This is relevant because
was enrolled as a student and McBain a teacher in the latter
part of Kestler’s career at the university. He then began working
at Norton in 1935 where he shifted to working with abrasives. Knowing
that he had started something with AeroGel he commercialized it by
creating a license agreement with Monsanto Co. in the early forties.
This company adopted Kestler’s method for creating Aerogels
with small changes for mass production purposes. Kestler coined the
name AeroGel, but when Monsanto made and sold it, they called it
The process started with adding sodium silicate to sulfuric acid.
The concentrations were controlled in order to produce a gel
with 8 percent silica. It was then aged for several hours where
into a gel. The gel was then flattened and washed with water
to remove the sodium sulphate, the other product of the reaction.
was then soaked in alcohol in 4 stages. After each stage the
was replaced with fresh alcohol. This was done to replace the
water in the gel with alcohol, which was the unique step. The
replaced with alcohol because alcohol is much easier to remove
from a gel than water. It was then brought to an autoclave.
Here the pressure
was raised to and held at 1150 lbs. The temperature was then
raised to 550 °F. The alcohol then left as a vapor. Once 550 °F
was reached the temperature and pressure was brought back down to
normal. It was then manipulated or shipped according to its different
uses. Monsanto did not keep very good records of what its “Santocel” was
used for, but most of it was for insulation in some private and industrial
freezers. This was the process used by Kestler and Monsanto to make
this AeroGel. It has since then been changed and the process has
become much more efficient. (Ayers, 3)
- At Elevated Pressures: The Life and Science of Samuel S. Kestler. Ed.
Micael Ayers. 24 Apr. 2004 <http://eetd.lbl.gov/ECS/aerogels/kistler/index.htm>.