Fig. 7.—Rockingham (Raw Lead) used.
50·9 per cent. solubility.
50·9 per cent. total lead.
Ground-laying, colour-dusting, and aerographing to be done under locally applied exhaust ventilation. Proper receptacles to be provided for cotton-wool used and waste cotton-wool to be burnt. No short-sighted person to be employed to do either glaze or colour blowing, unless wearing suitable glasses, and certificate to this effect to be entered in the Health Register.
Litho-Transfer Making.
[25]—Transfers for the decoration of earthenware and china are made in special factories, of which there are seven, employing 257 persons. The patterns are impressed in the ordinary chromo-lithographic fashion, but as the enamel colours, containing high percentages of lead, are dusted either mechanically in the machine, or by hand by means of a pad of cotton-wool, danger from dust is great in the absence of maintenance of a negative pressure inside the dusting machine and an efficient exhaust draught behind the bench where the final dusting with flour, to remove the superfluous colour, is done. In one factory, before a fresh colour was applied to the adhesive pattern on the sheets, the machines had to be cleaned as far as possible of the previous colour used. To do this it was necessary for the attendant to enter a closed chamber at the back of each machine, so as to supply the powder to the hoppers which feed the rollers, or to clean them by means of a brush, sometimes as often as every half-hour. The upward exhaust ventilation applied to the interior of the machine tended to draw the dust created in brushing past the worker’s face, and led to severe incidence of poisoning. The remedy suggested by Pendock[26] was to dispense altogether with the need for entering the chamber, to maintain a slight negative pressure inside the machine by downward exhaust, and to remove the dust by means of a small vacuum cleaning plant.
At the same factory the flouring bench was in the same room as the machines, and the locally applied exhaust drew its air-supply from the general atmosphere of the room. Apart from faulty arrangement of the exhaust ducts leading to effects of too local a character, dust was drawn from other parts of the room, including the machines, so much so as to necessitate frequent cleaning of the glass hoods. Poisoning among those employed in flouring occurred. To remedy this, an air-grid with curved inlets at intervals of 2 inches apart, leading into a trunk in connection with a fan, was placed along the back of the bench and under the top of the glass hood. In order, however, that its action should not interfere unduly with the general ventilation of the room, but be, in large measure, independent of this, a somewhat similar grid, introducing air from the street outside, was fitted along the front of the bench. The whole arrangement was operated by one suction fan. Ten cases occurred in this factory in the year before this arrangement was carried out. In the three years since, three cases only have been reported. In the ten years 1900-1909, 48 cases were reported among 257 persons employed.
Vitreous Enamelling.
[27]—Surfaces, such as sheet iron for advertisement signs, cast iron for baths and gas stoves, copper for copper letters and tablets, brass for jewellery, and glass for lettering and decoration, are treated with glaze or enamel colours, which, either in the mode of application or subsequent treatment before final vitrefaction, give rise to dust.
In the manufacture of advertisement signs, glaze is swilled on to the sheet of iron. After drying, it is fired or vitrified, and upon this surface as many other coats of glaze are applied as may be wanted. As soon as the colour is dry, lettering is effected by brushing away the dried (but not fired) glaze exposed through stencils.