-15— 
Revised Recommendations for Azobenzene 
Dr. W. E. Blauvelt 
Department of eles al Cornell 
’ March 5, 1944 
The best method of fumigating with azo~- 
benzene in houses having steam is the use of 
O% azobenzene power, made into a paste with 
water a paint on the steam pipes. The 
70% azobenzene powder is available from the 
following companies and through most dealers 
in floriste' supplies, umer the following 
trade names. 
Azofume 70-Plant Products Co.,Blue Point, 
ABZ Fumigant-Atlas Powder Co., mation: 
Hypozene-Hydroponic Chemical Co., eee 
Mite-Y-Fume-Andrew Wilson Ino., sprinetieia, 
Hot water pipes are not satisfactory for 
vaporizing azobenzene powder. In houses with- 
out steam, fumigation can be done with lamps 
or hot plates as described later. Azobenzene 
pressure fumigators and other devices not re=- 
quiring lamps are being developed and look 
very promising. 
DIRECTIONS FOR USE OF 70% AZOBENZENE POWDER 
1. Caloulate carefully the cubic capa- 
oity and amount of fumigant required for each 
house, and record this for future use. A 
satisfactory dosage of 70% azobenzene powder 
for most houses is 1 pound per 40,000 oubic 
feet of space. 
To calculate the oubioc capacity multiply 
the length of the house by «Lith by the aver 
age he » in feet. (To get the average 
height, measure the height from floor to 
ridge and floor to eave, add and divide by 2). 
For example: A house 250 feet by 50 feet has 
250 x 50=12,500 square feet area, If the 
height at the ridge is 20 feet, and the height 
at the eaves 7 feet, then 20 plus 7 = 2/7, and 
27 divided by 2 = 13 1/2 feet average height. 
Then 12,500 x 13 1/2 s 168,750 oubic feet, 
To calculate the number of pounds of 
70% azobenzene powder required, Arete the 
number of thousand cubic feet {the nearest 
whole number) by 40, For example: If a 
house 18 168,750 ocubio feet, then 169 divided 
by 4o = 4.2 pounds, or 4 pounds, 3 ounces. 
2. IMPORTANT - Pick a time to fumigate 
when you can maintain the proper temperature, 
The best temperature is around 75 degrees F., 
with a range of 70 to 85 degrees. Lower tem—- 
peratures are more dangerous than higher ones. 
A drop in temperature below 70 degrees during 
fumigation is very likely to cause injury, 
while temperatures have often gone to 90 or 
even 95 degrees without causing any important 
injury. Fumigation may be done either in the 
daytime or at night depending on the outside 
temperature. In cold weather it is best to 
fumigate in the daytime on a oloudy day, with 
moderate temperature, and little or no wind, 
starting at 9 to 10 A.M. 
3. Weigh out the required amount of the 
fumigant into one or more pails, Add water 
either by measure or a little at a time, and 
stir to a smooth thin. paste the consistency 
of paint. One to one and one-half pints of 
water per pound of powder is about right. 
4, By means of a 3- or inch paint 
brush (a No. 1 oval varnish brush is excel 
lent), apply a thin coat of the paste to the 
upper surface of four cold steam pipes the 
length of the house. Treat two pipes near 
the sides and two near the middle of the house, 
In extra wide houses treat one pipe per ten 
feet of width. To insure even distribution, 
treat 4 or 5 feet of pipe, skip 2 feet, and 
repeat, then go back and apply any material 
left to the blank spaces. 
5. Close the vents and get the tempera 
ture up to 75 degrees before starting the 
fumigation. This can be done while applying 
the material. Then turn on one pair of vapor 
izing pipes, or half of those treated. The 
heat melts the azobenzene, which then fumes 
off as a visible orange colored vapor. An 
hour and a half later turn on the rest of the 
treated pipes. The first set may then be 
turned off or left on, depending on the tem 
perature. 
6. Keep the vents olosed for six hours 
from the time you turned on the first vapor 
izing pipes. Keep the temperature around 
degrees or above for the entire fumigation 
ae “Then ventilate. 
7. Ventilate for at least 3 hours with 
plenty of steam on and vents adjusted to drop 
the temperature slowly (3 or 4 degrees an 
hour), This is Peps 
DIRECTIONS FOR USE OF AZOBENZENE CRYSTALS WITH 
LAMPS OR HOT PLATES 
For vaporizing with lamps or hot plates 
azobenzene crystals should be available from 
the same companies handling the powder form, 
The dosage for azobenzene crystals is 1 
pound to 57,000 cubic feet, or I ounce by 
weight to about 3,500 cubic feet. By using 
one lamp or hot plate for each 7,000 cubic 
feet, the total dosage will be 2 ounces by 
weight for each lamp. A 1 1/2 fluid ounce 
jigger holds approximately ounce by weight 
of azobenzene crystals when level full, Thus 
2 level jiggerfuls is the total amount for 
each lamp at this spacing. The crystals 
should be vaporized over a period of 2 to 3 
hours. To be safe, it is best to put in one 
half the amount (1 level jiggerful) at the 
start, and the rest at the end of an hour to 
an hour and a half. Adjust the heat so that 
