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

222 CORK INSULATION
filler and then with a good elastic enamel, such surface will
present an efficient barrier to the entrance of moisture. An
elastic enamel is required, to withstand the contraction and
expansion of the room surfaces due to changes in temperature.
The Portland cement plaster, however, is of such nature as
to expand and contract a considerable amount, under cold
storage room conditions, so much so that it has long been
the practice to score the surface of such plaster finish in four
foot squares to confine the checking and cracking to such
score marks, or, if you wish, to provide expansion joints,
similar to the expansion joints in concrete sidewalks. The
weak points in enameled troweled plaster are these score
marks, or expansion joints, and especial care must be taken
to keep all such cracks so well closed with filler and enamel
that little, if any, moisture will contact with the <strong>insulation</strong>
through that source. To do this is not as difficult as it may
sound, or as some would have us believe; for it is, in many
cold storage rooms, entirely feasible and practical to use
enameled troweled plaster on walls with entire success, and
if to the plaster mix a small portion of some good and suitable
integral waterproofing compound is added, the value of the
plaster as a protective coating will be enhanced.
The service in cold storage rooms of cold storage buildings
is not usually as severe, from the standpoint of moisture, as is
the service in daily ice storages, milk rooms, poultry chill
rooms, and a host of small cold storage rooms in small plants
because in cold storage buildings the rooms are not, as a
rule, entered nearly as often as are the cold storage rooms in
small plants, and when the rooms in a cold storage building
are entered it is invariably through anterooms that keep
the warm, outside air from rushing directly into the cold
storage room and precipitating its moisture upon cool surfaces
of every kind. Consec^uently, the need for the most
efficient protective finish for the interior of cold storage rooms
will be in rooms operating at moderate temperatures, such as
from 28° to 35° or 40° F., in which rooms the moisture pre-
cipitated upon cold surfaces is not converted into frost
crystals, or not so quickly converted but that there is an op-
portunity for some of it to be absorbed.
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