02 BULLETIN 1136, U. 8. DEPARTMENT OF AGRICULTURE 
withdrawn for reading; obviously they must be read immediately 
unless they are of the maximum-reading type. When it becomes 
necessary to enter a hot kiln an assistant should always be on hand 
for help in case of emergency. 
DRESSING TO WITESTAND KILN TEMPERATURES 
A certain degree of protection against heat at the operating tem- 
peratures of the kiln may be secured by the use of extra heavy 
clothing, preferably wool, of heavy, rivetless leather gloves, and of 
a mask or a hood. A gas mask with a special ice-filled container 
will cool air for breathing. To secure greatest results from heavy 
clothing it should be as vapor-tight as possible from the soles of 
the shoes to the top of the head. The wet-bulb temperature, rather 
than the dry-bulb value, is the prime determining factor in the 
matter of physical discomfort. An atmosphere with a wet-bulb 
temperature of 135° F. or higher can not, as a rule, be withstood 
unprotected long enough to make entry into the kiln practical. If 
a smoke machine is to be used at such a temperature, a 2-valve 
rubber syringe bulb should be fitted to its mouthplece. 
WEIGHING KILN SAMPLES 
The samples should be weighed frequently enough to determine 
accurately their changes in moisture content. The percentage of 
moisture should be calculated immediately after each weighing, 
and a chart, showing graphically the loss of moisture day by day, 
should be maintained. The daily temperatures and humidities may 
be plotted on this same chart, which can then be compared with the 
drying schedule for the detection and the correction of differences. 
Plotting the temperature and the humidity of the schedule on the 
same sheet will provide the most convenient means for comparison 
of the schedule and the actual run. (Fig. 14.) 
KILN RECORDS 
In addition to a kiln-performance chart, it is desirable to keep 
a permanent record of the other details of each run. Forms for this 
purpose are provided by some of the kiln manufacturers and can well 
be used wherever they are applicable. Many an operator, however, 
prefers to make up his own form. 
Excepting for the most simple class of routine drying, each run 
in any kind of a kiln should be identified fully, to permit quick and 
positive reférence to the kiln-performance record covering it. Then, 
if trouble subsequently develops with any lot of stock, examination 
of its history will usually show the cause. Naturally this cause may 
be some factor in its life before it reached the kiln rather than in its 
handling through the kiln, but only adequate records will disclose 
that fact. A run in a compartment kiln may be identified by number 
or by date; both means are preferable to either alone. The record 
of a progressive kiln of necessity is kept by days; each truck load 
of lumber going through such a kiln can be numbered—it is common 
practice to do so—and then in addition should be tied in with the 
kiln record by dates showing the time both of entering and of leaving. 
