Once the speed has been determined and the lever set the apparatus requires merely the supervision of an operator, who may devote considerable time to helping his assistants reload another carrier while the one in the tank is emerging. Generally only a limited number of carriers are required.
When the work is to be removed between coats a large percentage can be handled without tack in a short time after it is taken from the varnish.
In the introductory carrier, parts like piano tops, which are finished on all sides, require a little additional care because of the difficulty of handling. This contingency is provided for by the use of special head pieces.
In emergencies, for rushing out an extra quantity of work, carriers holding falls, frames and small parts may be immersed in one-half the interval usually required.
For example, these carriers can be withdrawn in from fifteen to twenty minutes, whereas for carriers including sides from twenty-five to thirty minutes are required. The carriers are equipped with head pieces adjustable to meet all peculiar local factory requirements. In fact, these carriers can be constructed by the manufacturer to meet all his demands.
The number of carriers necessary depends entirely upon the volume of work to be handled. But it is desirable, when possible, to have a sufficient number of carriers to hold all the work until the varnish is sufficiently dry for rubbing. In this way a tremendous amount of labour and time is saved.
Permanent carriers, in which the work has been secured by ordinary screws, have been constructed by some manufacturers at an unusually low cost by their own machinists in their own factories.
The work in the carriers can be easily dusted by means of air-bellows or a compressed air-blower. Work finished in this manner is so clean that the usual sanding is not necessary and a considerable amount of labour thereby saved.
That the Standard hydraulic immersion system of automatic finishing of pianos has distinct advantages over the ordinary hand process is obvious even to the casual observer. Among the numerous advantages which have been effected the following seem to be worthy of special consideration:
It constitutes practically the factory's entire varnishing force.
Its use insures an even coat, free from imperfections.
Coating both sides of the work preserves the cases considerably from shrinking and warping. A great deal of labour is saved by varnishing both sides at once.
It requires very little more varnish than the old, slow, hand method as there is no waste from brushes and pots and absolutely no dripping outside the tank.