The bottom, one middle, and the top course, are crossed or checkered in setting eight high, and Fig. 68 will show the manner of plac ing them in the kiln. The brick are set one directly over the other on edge ; the " cross-ties" shown are to hold the body and keep the pressed brick from " wabbling " or slanting from either side. Great care and experience in setting as well as in burning kilns containing quantities of pressed brick are very essential. Too hard firing in settling the kiln is liable to cause all the pressed brick to " tumble" or fall, and the fires at this stage are consequently lighter and more frequent than when the kiln contains only common brick. The pressed brick are also handled much more carefully than common brick, being taken up one at a time, placed lightly on barrows, and are carefully handled and tossed also one at a time to the setter. No extra money is paid to the setting gangs for handling pressed brick ; the work is included in the task.
In all stages the " gluts" as well as the finished green pressed brick should be protected from unequal drying ; the sheds in which they are made should have movable slat sides, which are closed during periods of strong winds.
When the " gluts" for pressed brick are made by machinery, the clay should be wet, and the brick, when they issue from the machine, should be soft enough to allow the finger to be forced into them. The gangs which re-press machine-made front brick are composed of four persons, if handled on barrows, and three if handled in the brick cars, the members of the gang being the presser, off-bearer and rubber, or sander. The brick are run through in a hurry, three thousand being a day's work. Brick made in this way are not usually suitable for the lower story fronts of fine buildings ; but, when economy is an object, they can be used in the upper portions where their defects can not so easily be discovered. This is hardly honest, but a great many neat fronts are thus put up in neighborhoods that would not justify the employment of first quality and high-priced brick.
When care is taken with every stage of the work, and the " gluts" are made very soft, and well and thoroughly sanded and rubbed, it is possible to produce pressed and ornamented brick which are not only good in appearance, but which are strong and durable, and which can with safety be used in place of first-quality brick for cornices and other work occupying a high position in buildings.
Geo. Carnell, of Philadelphia, Pa., the well-known manufac turer of hand and power brick presses, gives the following con cise directions for making fine front brick : 1. It is important that the clay should be well tempered, a
clay-tempering wheel producing the best.
2. It is necessary to have sheds built expressly for that pur pose, the roof being made so it can be opened to admit sun and wind when required ; doors are also made to protect the sides of the shed in case too high winds prevail. In sheds built this way, the brick can be dried with better regularity.
3. The brick should be moulded free from flaws or sand cracks ; the moulds, when in use, must be kept well cleaned by the off-bearer, as the accumulation of sand or dirt on the sides of the moulds, if not scraped off, will make a variation in the sizes of the brick when they come to be pressed.
4. The brick are placed on the floor to dry. When nearly dry a light sieving of sand is put over their faces, and they are then turned over that they may dry more regularly. When the brick dry too fast a damp carpet can be placed over them and sprinkled occasionally with water.
5. When the brick are ready for pressing, say when they can be handled without finger marks, the press is then taken to the brick (or vice versa) ; the brick are then carefully placed in the press mould, care being taken that they are not marked while dropping them in. The brick must be kept free from finger marks.
6. The mould, plate and lid should be kept clean ; a sharp pointed hard wood stick is best to clean the corners of the mould out with. This should be done, and the mould wiped out every few brick ; occasionally it will be found necessary to raise the bottom plate and scrape the dirt from around the sides ; after cleaning apply a little oil.
7. From the press the brick are carried with paddles and laid on their flats, about six high.
8. When the brick are partly dried they are rubbed carefully with the hand and hacked on their edges, pigeonhole shaped, for drying. By pigeon-hole hacking we mean placing the brick two on two, and reversing them every course. After they have become hard enough to handle without danger of injuring them they are placed on barrows, with pieces of soft carpet or blanket between the courses ; they are then hacked in sheds and are ready for the kiln.
9. After the day's pressing is finished take the plate and plunger out of the mould, scrape all the dirt off, wipe clean, and oil the mould, plates and plunger. By keeping the press and mould clean it will give better satisfaction.