" If stones abound in any quantity they should be separated from the clay by a roller crusher, or if they be not large and of a limestone formation, a disintegrator or pulverizer to reduce them will answer. In the latter contingency the crushed stones form an integral part of the clay and are worked up with it. Experience alone can demonstrate whether they deteriorate its quality or are otherwise objectionable.
" The pugging process which follows is one of importance, as upon its thoroughness depends largely the uniformity of your material. A pug-mill, in addition to the one which usually forms part of the machine, relieves the latter of excessive strain and better prepares the clay for all future work upon it ; in fact, by its use the clay is thoroughly prepared before reaching the machine, whose only remaining duty is to strike out the brick.
" In sanding the moulds for use with the machine, a fine sand giving a rich, red color, is required. Where this is not obtain able, good results can be had by using moulding sand, or the dust from the rattle, procurable in any foundry. Sieve through a very fine sieve, not less than No. 6o.
"Tempering clay by a wheel and moulding by hand is still followed in many localities. Results from this method, although slow, have always proven satisfactory and profitable.
" What machine, if any, is best adapted for re-pressed brick? I have seen very excellent brick made on all machines, hence I do not advocate any kind of machine or any special mode of manufacture. The machine is but the agent for putting the gluts into shape ; for producing the necessary amount of clay in each. This, I claim, can be done successfully by any of the good ma chines now on the market, other conditions being favorable. As to the machine best adapted to the manipulation of any special clay, it is a question to be determined only by actual experience or trial with it.
"The re-press, although a small machine, plays a no less important part in the production of fine brick than larger and more expensive ones. The press should at all times be kept clean and its working parts oiled. I commend the method in use in some of our yards which requires the pressman to clean and oil the press thoroughly at the completion of each day's work.
"The dies of the press should be frequently dressed or re-lined, and the plungers packed out to fit snugly therein ; perfect brick may not be expected from an imperfectly con structed or partly worn die, as each brick will take on all the imperfections of the press die.
" I am frequently asked how much pressure is required to re-press a brick. I have never yet attempted to answer this question, and will not do so here, but will say : When the edges and corners of the brick are perfectly developed, the end sought by re-pressing is attained. Multiplied tons of pressure will not do more.
"A skilled workman who can exercise judgment in handling and working the press should operate it. When the press is in operation the die should be wiped off with an oiled rag or brush after each brick is pressed, or as often as required to prevent adhesion of the brick to the die. An oil suitable for this purpose is composed of coal oil one part and lard oil three parts, or coal oil and engine oil in the same proportion, or coal oil and rancid butter ; the latter being warm and mixed makes an excellent lubricant.
"The little paddles by which the brick are removed from the die after pressing must present a smooth and even surface to the brick, and should be rubbed off occasionally to remove accumulations of clay, or redressed when their surfaces be come uneven by wear.
"The drying sheds I consider as necessary to the produc tion of good pressed brick, as the press and other fixtures. By their use the sun is excluded, the air currents are con trolled, and you are better able to produce brick of an even temper throughout, without which good results in re-pressing are impossible. Brick dried in the sun or out of doors, dry hastily and unevenly ; their inner portions remain soft and mushy while their surfaces are crusty, and their corners and edges dried prematurely ; thus rendering them unfit for the re-press. The brick must dry slciwly and regularly. This result can be obtained by the drying shed.
" The drying shed can be arranged with racks similar to an outdoor rack for drying. They should be built wide enough apart to allow the trucks and presses to be wheeled between them, and not so high but that the pallets of brick can be re moved from the top shelves easily. Boards running length wise with the shed can be hinged, forming an easy manner of regulating the air currents. A moderate degree of artificial heat can be introduced to advantage.