Standard
STD 420-0003
Volvo Group
Version
1
Page
9
If the gloss readings, Fj, for the test pieces (glass plates) deviate by more than ± 5 % units from the mean value
and none of the test pieces is approved, test a further two glass plates and calculate the mean value of the results
obtained for all test pieces.
6.1.4.3 Calculating the fogging value F
To calculate F in %, the fogging value F
j
is first calculated for each glass plate by using the following equation:
5
100
R
R
F
05
01
15
11
j
×
=
∑
∑
−
−
where
F
j
is the fogging value of each glass plate in %
R
11
is the separate value measured on a glass plate after the fogging tests
R
01
is the separate value measured on a glass plate before the fogging tests
2
2
1
j
j
F
F
F
+
=
6.1.4.4 Standard deviation
The standard deviation of fogging factors “F
i
” for each plate is calculated using the formula:
1
4
)
(
4
1
2
−
−
=
∑
=
i
j
i
j
F
F
s
where
F
i
is the fogging value of each point of measuring in %
4 is the number of test points on the glass plate
This standard deviation indicates the homogeneity of the deposit. If the standard deviation is greater than 5 %, or if
the deposit is non-homogeneous, value “F
j
” is not usable and the test must be repeated.
6.2 Method G (gravimetric method, evaluating fogging using a balance)
6.2.1 Conditioning and drying
Before testing, the test pieces shall be dried at 23 ± 1 °C in a dessicator with phosphorpentoxide or silica gel in
accordance with table 2.
Table 2 - Drying times
Material Drying
times
Natural materials, test pieces
containing natural materials
168 h
±
2 h
Coated fabrics
48 h
±
2 h
Other materials
24 h
±
2 h
A skin will appear on the phosphorpentoxide or silica gel, which shall carefully be removed. Observe that water
absorption will create phosphoric acid. Attention shall also be paid to instructions as stated in safety sheets for
phosphorpentoxide.
