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

220 CORK INSULATION
slight variation in the height of track rail.) The width and
height of cold storage doors are always specified as "the
dimensions inside of frame" or "door in the clear." In the
case of the no-sill type, the height of the "door in the clear"
is understood to be the dimension measured from the lowest
point of frame at top of door to the concrete floor level in
doorway. (Consult manufacturers for detailed cold storage
door specifications.)
99.—Interior Finishes for Cold Storage Rooms.—It has
been noted that when water is precipitated on the plastered
surface of an insulated cold storage room, by the condensa-
tion of moisture from the air upon a cool surface, a part of
such water is absorbed by the plaster by capillarity, which
slowly disintegrates the plaster while placing a portion of
such moisture on the surface of the <strong>insulation</strong> directly behind
the plaster. <strong>Cork</strong>, unlike other materials, will not take up
this water by capillarity, but such water may by gravity find
its way into the corkboards through possible small interstices
or voids between the particles of cork bark that comprise tlie
sheet of <strong>insulation</strong>.
It has also been noted that the modern corkboard product
of maximum worth must be compact and free from voids to
the greatest possible extent, although the nature of the raw
material, and the manufacturing process that must be fol-
lowed, do not permit of the elimination of all voids, especially
surface voids. Water in contact with corkboard on the walls
of buildings can be expected to penetrate the <strong>insulation</strong> to
some extent at least, such penetration having been known in
extreme cases to reach a depth of as much as an inch or so.
Thus it should be evident that the finish over the cOi'-board
<strong>insulation</strong> on cold storage room walls should have more
than passing attention, but the subject has long been neg-
lected and not until comparatively recently has it had serious
attention.
Portland cement plaster troweled smooth and hard for the
finish coat over the last layer of <strong>insulation</strong> is much better
than plaster floated ; because the troweled plaster is less porous
and possesses less capillarity. This fact does not seem to be
appreciated by many, however, for plaster floated has long