Metal Forms And Ornament

Cast iron forms for ornamental products are frequently used. These are cast in a foundry from wood patterns made for that purpose. The degree of ornament that can be given to any concrete work depends largely upon the skill of the wood worker who makes the pattern from which a cast iron form is cast.

Commercial Forms

Except for the practice obtained in woodworking and for the pleasure of doing the work, it does not pay to attempt to manufacture concrete molds for some kinds of objects. This is particularly true of forms for concrete block, concrete brick, plain concrete fence posts, etc. By far more satisfactory results can be obtained when making these products if some one of the many commercial molds now on the market is used.

Proper Planning Of Forms

Planning forms or molds for ornamental objects so that they may be removed from the object without injury to it requires in some instances considerable forethought. Division points must be along such lines as to give the least resistance or friction when removing parts of the form. At no point should any section of the form bind or cling to a projecting part of the concrete object, as the least sticking to the concrete makes it likely that a portion of the surface will be marred or broken. Molds for fluted columns, for instance, may have to be divided into eight or more sections so that they can be removed without injury to the concrete. Even the mold for a cylindrical object may have to be divided into three or more parts. There is no possibility of injuring the product when removing such a form from the concrete if the form has been properly divided. If a form of this kind were to be divided merely into two parts, it is possible that the division line would not make the supposed halves equal, hence one section would bind or cling to the cast. This applies with but few exceptions to all circular molds. As the average projections can be planned so that the greatest length will come at a division point or in such a position between division points that the mold will not cling when removed, such planning should be a part of the form construction. Cores for objects that are hollow must be planned so that they also can be readily withdrawn without hammering or pounding or without exerting any force on the object that might tend to burst it while the concrete is soft.

Examples Of Division Of Forms

Elsewhere are examples illustrating the points just brought out and showing how forms must be planned so that the various sections will part from the concrete without injuring it.