The development of a disintegrating core-body for use in an art bronze foundry, which employs the ceramic shell investment process, begins with an investigation of four principal materials that will constitute the core formula. The specifications for the disintegration of the designed core-body formula fall within the parameters that are normally set and used in the ceramic shell art bronze casting process. The raison d’ être for the disintegrating formula is based on the premise that cement breaks down (spalling) after being subjected to heat above a certain temperature. It was shown that pure cement in the form of naked test bars 100 mm x 20 mm x 20 mm does indeed break down into separate pieces when fired to and above 9000C; where 9000C is the lowest recommended temperature required for sintering the ceramic shell investment mould. The addition of calcium carbonate to pure cement in the form of naked test bars, produced a more unified formula that did not break into separate pieces when fired to 9450C. However this combination of cement and calcium carbonate had a slow setting time of 12 hours and a shrinkage value of 2,3%, which were both above the parameters being sought for a quick-setting formula with a shrinkage value of below 1%. The combination of cement, plaster of paris and silica produced formulae that set within six hours and had shrinkage values of less than 1% but did not disintegrate within 72 hours. It was only after the addition of calcium carbonate to the these mixes that formulae resulted that set within six hours, had relatively low shrinkage values and showed signs of breaking up after 60 hours. It was further shown that by altering the ratios of cement, plaster of paris, calcium carbonate and silica, that the parameters for quick-setting formulae with shrinkage values of 1% and below, that also disintegrated within 55 hours, could be achieved. xvi It was also proved by subjecting these formulae to higher relative humidity conditions that the disintegrating times could be reduced and brought to below 48 hours. Selected formulae were then subjected to temperatures of between 9000C and 10000C. It was found that as the temperatures were increased so the disintegration times were reduced and were even further reduced under higher relative humidity conditions. It was found from the above experiments that the selected formula determined to be suitable in all respects as a disintegrating core-body was too difficult to remove from the hollow bronze cast when subjected to an actual bronze pour. Further experimentation using increased proportions of silica in the formula resulted in a final core-body that could be quickly and easily removed from its bronze cast as soon as the core-body had cooled to room temperature. The selected core-body formula (F21D) that was used in the final set of bronze casting procedures was found to function optimally when fired to a temperature of 9000C and could be quickly and easily removed from the bronze casts leaving a clean inner bronze surface, free from any remnants of the fired core. The document concludes by recording the delimitations and advantages of the final core-body formula F21D, as well as making recommendations based on these parameters for further study relating to disintegrating core-body formulations.

The purpose of this investigation was to develop a method of burning out expanded plastic patterns invested in ceramic shell molds. Technological information suggested that the procedure was not feasible because plastic expansion or gas combustion invariably spoiled the mold. However, burning out expanded plastic patterns would provide a practical method of using such materials in the sculptor's studio; combined with ceramic shells, the patterns would promote accurately detailed castings with ease and convenience.

Thesis (M.A.)--Reformed Theological Seminary, 1986. / Includes bibliographical references (leaves 130-136).

No description available.

This thesis deals with an investigation of the feasibility of using the multiple-piece plaster mold as a vehicle for teaching the indirect method of sculpture to the adolescent student. It is based upon the assumption that the students involved in the processes described will have had previous experience with the tools, techniques, and materials to be used. The investigation centered around the ability of the students to express themselves through the development of a sculptural form. The teacher's role was to assist the student identifying, expressing, and evaluating his individual goals against those goals established by the teacher. Instructional goals were present, but relegated to being of secondary importance to those goals possessed by the student. My research established the physical possibilities of casting both in aluminum and concrete using the multiple-piece plaster mold. Research procedures centered around the investigations of industrial methods used in forming aluminum castings in plaster molds. My investigation revealed that solid aluminum castings in plaster molds offered exciting artistic possibilities, but that rigid control of the preparation of the molds and the casting process was necessary before aluminum casting could be introduced to the students. Concrete casting was also found to be of use in the secondary class room. Prior to the introduction of casting to the students, a questionnaire was given them to determine their sculptural concepts and their past experience with materials, tools, and techniques. The information gained gave support to the exploration of the casting process. I then formulated a unit of study designed around the student's successfully completing a solid casting in either aluminum or concrete using the multiple-piece plaster mold. This unit was presented as nine separate problems to be solved in the following sequence: designing in clay, constructing an armature, modeling a temporary clay form, forming a multiple-piece plaster mold, drying the mold, casting, chasing, applying a patina, and mounting a completed casting. The project was challenging and broadening for the majority of the students involved. They were able to use past experiences with implements, materials, and processes and incorporate these into this new learning situation. Group solutions were found to be the most useful method in solving problems in each step. Evidence suggests that group learning through association and cooperative problem solving is the most valuable result of this project. Aluminum proved to be the most popular material, but from an instructional standpoint it was found to be a much more demanding and complex material. I found that it was important for the students to have had previous experience in the use of similar materials, tools, and methods to those encountered in this project. Due to the complexity of this project, prior knowledge in sculptural concepts is also clearly indicated as being necessary. I conclude with the recommendation that this unit of study be undertaken by advanced students as a summary project after several years of study.