A TERRA-COTTA FACTORY.
The departments or divisions of the work in a terra cotta factory seem to indicate a five-storied building as the most convenient for the purpose, the divisions being as follows : The basement or first story for the milling and storage of the prepared clays and for the operations which belong to the firing of the kilns.
The ground floor or second story for the loading and unload ing of the kilns, and for the selection and fitting of the burned product previously to its delivery to the store or purchaser.
The third story for the pressing and finishing and drying of the heavier, coarser, and most bulky pieces of terra-cotta work.
The fourth story for the pressing, finishing and drying of the smaller ornamental and finest description of work.
The fifth story being reserved for the studios of the modelers and for the model and mould-making shops.
The model and mould-making shop is the most important portion of a terre-cotta factory, and like the head of a man, should be at the top, so as to be as far as conveniently removed from the dirt and noise of the other departments.
In this department are prepared the models and sculptures of the business, and the moulds from which the clay duplicates are to be made.
The idea of the architect having been conveyed to the top story, there takes a substantial form for the first time, and be comes a material having size and weight.
It then passes downward, and as in all orderly progress does not retrace its path ; if it is of a decorative or artistic quality, demanding skilled labor rather than mere material, it stops awhile on the next story to be put into its proper progression.
Panels with modeled surfaces, sculptured forms, finials, man tels, and any other delicate works, are thus done next to the top, just as all the higher employments of men, such as sculp ture, painting, writing, calculating, etc., are performed with the hands in close proximity to the head. Should the work, how ever, be of a heavy, coarse, or bulky nature, such requires more muscular force, less mental service, and a greater amount of material ; it goes a story lower to pass into its next stage of progress.
In the production of one ton of terra-cotta ware there are re quired to be used nearly 700 pounds of water, or more than 80 gallons. About 70 gallons of this surplus moisture will have to be evaporated in the process of drying, and the final 10 gallons will pass off after the work is placed in the kiln in a form known as water-smoke.
By making the factory structure several stories in height and placing the kilns at one end of the same building without any intervening partitions, it will be found that by the evaporation of the moisture the drying of the work can be carried on in a very economical manner.
Fig. 182 will be found useful for illustrating the practical workings of this method ; the sketch represents a building five stories in height, with the kilns located at the northern or cold end of the building.
It will be noticed that the kilns are placed at one end of the shops and grouped together, so as to concentrate their heating capacity in one place as much as possible. This is done in order to create a constant stream of air flowing toward them from all parts of the workshops, attracted by the well-known law which causes the heavy or cold air to rush toward the warmer or lighter air adjacent ; and these generators of draught should always be placed at the northern or coldest end of the building.
The floors and the roof are not allowed to come in contact with either the brick or iron-work of the kilns, but there is a clear space averaging eight inches all around them, which forms a passage for the moistened air to escape upward and outward, as is indicated by the arrows and dotted lines in the illustration.
This area or space is covered with an umbrella-shaped hood about eight inches above the roof-line, which prevents the rain or snow from driving into the building.