Cork insulation; a complete illustrated textbook on cork insulation ...

172 CORK INSULATION
test consists of boiling a piece of <strong>insulation</strong> <strong>complete</strong>ly submerged
for three hours at atmospheric pressure without its
disintegrating and without its expanding more than two per
cent in any direction. Pure corkboard of standard quality
easily meets the requirements of this test, merely demonstrat-
ing in a simple laboratory way that corkboard <strong>insulation</strong> is
proof against deterioration in service from the destructive
action of moisture that is ever present at cold storage tem-
peratures.
83.—Sanitary and Odorless.—Any insulating material employed
at cold storage temperatures usually encounters
foodstuffs, and should therefore be perfectly sanitary and
free from mold, rot, appreciable odor or vermin. For these
reasons any <strong>insulation</strong> in which binders are used, especially
pitch, is dangerous, since the delicacy of many foodstuffs
makes them peculiarly susceptible to tainting and contamina-
tion.
Pure corkboard contains no foreign binder of any charac-
ter and the cork bark of which it is composed is inherently
moisture-proof. Therefore it will not rot, mold or give off
offensive odors ; and
if corkboard is properly erected, it is
vermin-proof. Cold storage rooms insulated with pure cork-
board, and finished with Portland cement troweled smooth, as
recommended by the United States Department of Meat In-
spection, are easily and indefinitely kept in sanitary and hy-
gienic condition by ordinary washing and cleansing methods.
The sanitary and odorless qualities of an <strong>insulation</strong> for cold
storage temperatures are of very real importance, and pure
corkboard is easily the standard by which all cold storage
insulating materials are judged.
84.
—
Compact and Structurally Strong.— It has been noted
that a particle of cork bark is made up of a myriad of tiny
sealed air cells, separated from each other by thin walls of
tissue of very low density, each cell containing a microscopic
bit of air. In the manufacture of pure corkboard. of standard
specifications, the particles of cork bark are sufficiently com-
pressed in the molds to eliminate the voids between the