MAKING.
Any good wire-cut brick machine can be used for making the brick, provided only water from the lubricating die is allowed to come in contact with the clay while it is being moulded.
In England nearly all brick which are to be enameled are made by hand.
It is of great importance that the size of the mould should be such that when a proper allowance has been made for shrink age, the brick, when placed in the press box, shall fill it as uniformly as possible, and of just right proportions to enter the box cleanly.
In employing machinery, care must be exercised in order that none of the oil used for lubricating the cutting table or rollers, or any other portion of the mechanism where oil is commonly used, is communicated the green brick.. Brick containing oil cannot be successfully enameled, and all brick which contain grease of any character must first have such grease removed from their surfaces before they are dipped.
Paraffine and olive oil are the best lubricants to be used on all machinery to be employed for the making or pressing of brick which are to be enameled. Such lubricant oils as are generally used for brickmaking machinery must, under no cir cumstances, be employed. It is desirable that a lubricating die, whose only lubricant is water, should be employed with stiff clay machines used for the making of the brick. The brick should be made stiff enough so that when they come from the cutting table they can be hacked on the hot floor seven or eight courses high, and they should be allowed to so stand without any further bundling until the steam has been dried out of them. One great trouble with brick made by machinery is that sufficient attention is not paid to the adjust ment of the die of the machine. The die must be a little
smaller than the mold-box of the press, otherwise the brick require dumping to make them pass free and clean into the press box. Another trouble with machine-made brick is that sufficient care is not exercised to keep them free from finger and thumb marks, and from other defects which materially lessen the value of the finished product. When machinery is under the management of careful and intelligent men, there is no reason why the machine-made brick should not fully equal those made by hand. If made by hand an experienced moulder must be assigned to the work and brass molds only should be employed ; no sand must ever be used—only water to make the brick slip clean from the mold—the molds being dipped in the water-tub after every two brick are made.
The brick are made on a hot-floor the same as other fire brick. The floor upon which the brick are placed to harden must be only warm, not hot, and the off-bearer must put the brick on the floor very carefully, in order not to destroy their perfect shape. Iron plates, however, are apt to oxidize, and this oxidation becoming incorporated in a minute quantity with the edge of the brick lying on the plates, has a tendency to discolor the body and glaze, causing the brick to look very unsightly. The flat sides of the brick are usually depressed— the name of the firm manufacturing the brick being in one de pression and the initials in the other. This gives the mortar a better hold and also makes the brick easier to burn.