MOULDING THE GLUTS.
" In coming to the first crude form in which pressed brick are generally moulded after selecting and preparing the clays, we shall more particularly speak of such brick as they are gen erally made in the East, that is, what is termed a regular hand made brick. They are, as you all probably know, first moulded in " glut " form one at a time by hand, and then al lowed to dry to a certain consistence before they are re-pressed. We have found that the better we can have this first "glut" or crude form of the brick moulded, the better the finished article will be.
" Many pressed brick manufacturers have been led into error by supposing that any way of getting the first form of the brick for re-pressing is good enough, that is, they will naturally think if they only get the amount of clay required for a brick in almost any shape or form, it is all that is required, taking it for granted that the press when it comes to the repressing must of course make a brick from it that will be perfect in both shape and quality. This is a great error, for the reason that there is very little material from which we have ever seen press brick made that would not show the defects caused by improper moulding, even after the brick might be most carefully re pressed.
" One of the first qualities that is required in a good press brick is for it to have a fine surface or skin on the sides and ends of the brick, as they are the parts that are exposed to view when laid in the building.
" This skin should be smooth and uniform and not broken, and we find by experience that the only time to get a fine sur face to the brick is in the first moulding of the " glut " brick. As you are aware, that is done by the proper application of a coating of moulding sand on the outward surfaces of the brick in the process of moulding. That is, each proportion of clay required to make one single brick is thoroughly rolled in fine moulding sand and the moulds are also coated with it, and the sand not only gives the brick a fine skin or coating, but it also causes the brick to slip freely from the moulds. This, I think, has been one of the main difficulties that have been met with in making brick by machinery and then re-pressing them for front brick.
" In making brick with what is termed a soft-clay machine, the clay, as a rule, is forced into the mould in a raw state, and we can only depend on what sand we can get on the inside sur face of the mould to form the coating of the surface of the brick when finished.
"Then again, the sand that is generally required to be used in making brick with a soft-clay machine in almost all cases is too sharp to form a coating to the brick, for the reason that very sharp sand will not combine properly with the clay to form the skin to the brick. You will find that when too sharp a sand is used, instead of adhering to the clay and forming a smooth un broken surface to the brick, it will become detached as the brick dries and rub off very easily, and of course leave the brick with a rough and broken surface.
" In moulding brick with what is galled a stiff-clay machine and then re-pressing for front brick, we do not think this trouble is met with to such an extent, for the reason that no sand at all is required to make the brick slip, as the clay is forced through the die of the machine in a square form called the web, and then cut by wires into the individual proportions that are required for each single brick. By taking a very fine sand (powdered clay would answer as well) and applying it to the web of clay as it passes from the die of the machine, we think that the matter of coating the surface of the brick to form the skin that we have mentioned can be accomplished if the sand ing is properly done.
" Now in giving you what we shall only call our own ideas concerning these two classes of brick machines that are most used in the making of the glut' for pressed brick, we will state that we have never used any kind of machine for the making of pressed brick at our yards, nor do we know of any ever used in Trenton, so you can see that we are not talking in favor of any one brick machine, nor on the other hand do we condemn any ; but we have simply mentioned these facts about them in regard to their making a good pressed brick, and to bring out any good point any of you may have to give us on the use of brick machines in the moulding of gluts' for pressed brick.