Mix 5 grams of Zinc Silver and 2 ml of water on a glass plate with a spatula. Cover the resulting slurry with a quartz plate or, if necessary, a glass plate that is transparent to UV light. Cover a part of the upper part of the quartz plate with black paper, and place the entire glass plate with 5 minutes of potassium under a mercury-quartz lamp 20 cm away from the light source. Remove the black paper through 10 cents of gold, and then observe the difference in color between the covered part of the pulp and the covered part.
If the zinc-silver white is not light-resistant, the part covered by the black paper will have a lighter color; but for the light-fast zinc-silver white, no such difference can be seen.
The mercury quartz lamp should be closed in a special box when in use, and the operator should wear blue glasses, because the light is very harmful to eyesight. At the same time as the main test, it is better to carry out a control test (check test) with lithopone, which is obviously not fast to light.
As the light source for ultraviolet light irradiation, nPK-2, nPK-4, nPK-5 and nPK-7 types of high-pressure mercury-quartz lamps with different powers are widely used. Mercury quartz lamps of the type nPK.-2 are used in the paint industry (Fig. 34). These lamps can be used in AC circuits with a voltage of 127 volts (nPK.-4 lamps) and 220 volts and a frequency of 50 Hz with suitable switching devices. It can also be installed in the DC line according to the special machine circuit diagram. When used in the AC trunk line, the electrical parameters of this lamp are listed in Table 14. The electrical parameters of the lamps powered by the AC rear circuit are listed in Table 14.
The working position of the lamp is horizontal (the allowable inclination angle of this position should not exceed 15°). It is not allowed to place the lamp in another position, because it may overheat the bright pole and shorten the ignition time of the lamp. In order to prevent the risk of scalding and avoid ozone, when using this lamp, the safety cover designed by BB Kapace B 57 (BB Kapace B) can be used.
In Table 15 are presented approximately zero data for the relative distribution of energy on the spectrum irradiated by nPK type lamps (energy of spectral lines 3650/63A).
