100 DEPARTMENT BULLETIN 12 16, IT. S. DEPT. OF AGRICULTURE 
4. The amount of galvanizing or spelter coating will be determined in accord- 
ance with the methods for testing the amount of spelter coating on culvert 
metal. 
5. Chemical analysis to be conducted in accordance with the standard method 
of chemical analysis of plain carbon steel. A. S. T. M. A 33-24 (3). 
65. METHODS FOR DETERMINING WEIGHT OF COATING 
ON ZINC-COATED ARTICLES 
(A. S. T. M. standard method 
■J), serial designation 
Sue p. 1) 
a 00-^4, except as indicated. 
SHOP WEIGHING TESTS 
Select a pickled and washed sheet. Stand the sheet on edge and allow to 
drain for two minutes. The water remaining on the sheet will then amount to 
approximately 0.01 pound per square foot. 
Weigh this sheet with an accuracy of 0.05 pound, and subtract the weight 
of the water to obtain the real weight of the uncoated sheet. After galvanizing, 
reweigh the sheet. The increase in weight represents the coating. 
Where greater accuracy is desired, wash, dry, and weigh 10 sheets: then coat 
and reweigh. 
To determine the weight of coating in ounces per square foot, divide the 
weight of coating in ounces by the area in square feet in the sheet or sheets. 
SAMPLING 
(a) Sheets. — The laboratory samples for determining the average weight of 
coating upon a .ualvanized sheet shall be taken as follows: 
A 2 1 /£-in«h strip shall be cut transversely or diagonally across the middle of 
the sheet with its ends approximately 1 inch from each edge. Three samples, 
12 * t by 2 1 /! inches, or of equivalent area, shall be accurately cut from the 
middle and the two ends of this strip. These samples shall be cleaned with 
gasoline or benzol, then with alcohol and dried thoroughly before proe/eding 
with the test. 
The weight of coating in grams on a 2 1 / 4 by iy± inch piece (5.08 square Laches) 
is numerically equal to the coating in ounces per square foot. 
1 6 ) Wire. — Select either exactly 1 foot of wire or a definite length of wire as 
given in Table 8. depending upon the diameter of the wire after stripping. 
Clean the wire with gasoline or benzol, then with alcohol, and dry thoroughly. 
When using exactly 12 inches of wire for the test and obtaining the loss of 
weight (weight of coating) in grams, the formula is as follows: 
Loss of weight in grams 
Ounces per 
quare foot of actual 
surface. 
7.422 X diameter in inches of stripped wire 
It is sometimes more convenient to use a length of wire, as given in Table S, 
such that the loss in weight (weight of coating ) in grams will numerically equal 
the ounces per square foot of actual surface. 
Table 
-Lengths of wire to give grams of coating which are numerically 
equal to ounces per square foot of actual surface 
Size of wire B.W. <;. 
Diampter 
Length for test 
Si?eofwireB.W. G. 
Diameter 
Length for test 

Inches 
340 
.300 
.284 
.259 
.238 
.220 
.203 
.180 
.165 
.148 
Inches 
6H 
7H 
9 
10H 
Centi- 
meters 
12.1 
13.7 
11.5 
15.9 
17.3 
18.7 
20.2 
22.8 
24.9 
27.7 
10 
Inches 
0.134 
.120 
.109 
.095 
.083 
.072 
.065 
.058 
.049 
Inches 
14H 
17 
im 
22^ 
24V 8 
33 
Centi- 
meters 
30.6 
1 
11 
34.2 
2 
12 
37.7 
3 
13 
14 
15 
16... 
43.2 
4 
49.5 
5 
57.0 
6 
63.2 
7 
17..... 
18 
' 70.8 
8 
83.8 
9 
