to trust the expertise of our suppliers who offer a range of scanning tech so that we can combine scan methods in order to produce the best possible scan to preserve some of our client’s files. Reverse engineering the geometry of sculpture still has limitations, because most scanning technologies rely on line-of-sight information to generate the point cloud and subsequent mesh. There are technologies such as industrial CT that may be able to capture the complete geometry; however, they are limited by the density of the material that is scanned, the operating cost, and the space required for the machines themselves. The files are also not flawless and will often have artifacts such as air bubbles or internal structures that will have to be removed digitally. After the scan is complete, we
still require a physical version of the enlarged sculpture in order to cast the work. Over the past few years, Artcast Inc. has experimented with direct-printed positives as a means to bypass the slower and more costly enlarging processes, and as well for producing castable originals of pieces originating from 3D files. Both of our 2017 and 2018 submissions to the ICI Casting Contest were made using the technology and techniques learned in our print-to-casting process. Through our research we’ve determined that our preferred material, PMMA, is a powder that when bonded together in a binder-jetting process creates an original that may be used for casting. The prints do not require supports, are cast-ready when they arrive at the shop, can be modified in our wax room, and the gating system seems to adhere well to the printed material. Keeping the casting wall thickness even and precise at a thickness of 3/16 of an inch is often a challenge when making patterns using traditional wax on mould techniques; however, this is not an issue when using highly controllable current printing technology where not only the outer surface of the work is modeled with visual accuracy, but the interior can be digitally sculpted at a defined thickness and corners can be beveled and filled in order to prevent casting issues. Since printing is a far
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more precise and less hands-on process than brushing waxes into a rubber mould, time is saved when working directly from prints. Artcast currently has an in-house printer which allows us to print small pieces which require a very accurate fine surface. The ICI Casting Contest medallion original was printed on our machine in-house. Large sculptures, printed on industrial sized machines, are outsourced. One day we may have an opportunity to bring the larger technology on to our shop floor. However, it is still cost prohibitive. Monumental sculpture is created
by casting the piece in sections that can fit within the constraints of our shell dipping tanks, hence School of Fish was separated into fourteen printed sections to adhere to our needs. The sections that arrived were inspected and approved within hours of arrival, but there were some minor modifications made to the prints. Craftsmen also added the artist’s signature alongside Artcast, Inc.’s foundry stamp to help identify the makers of this bronze casting. The printed wax patterns integrate
extremely well in the rest of our standard casting process and function much like the regular pattern wax since the shell thickness we use for standard waxes accommodates PMMA 3D prints. Other printed materials may require extra layers and special attention during steam dewax as some materials are harder plastics. The steam dewax stage does not cause the PMMA prints to expand to the point of damaging the shell, they actually have a negative coefficient of thermal expansion. Special attention is required when we fire and burnout the shells, because the PMMA needs a higher oxygen availability to completely incinerate. Ash is never ideal so we inspect each ceramic shell and assess if repair or reinforcement is necessary. Due to the printed patterns accuracy
on School of Fish, assembly went extremely well. Because of the bronze shrinking when cooling, there will almost always be minor warping on an artwork. When making monumental work with many sections such as with this work, it was required that we pushed back the edges of the casting sections with the force of a 5 pound hammer and other
metal tools in order to properly weld the sections into a single large work. Luckily, due in large part to the digitally controlled thickness of 3D technology, the piece was assembled in a shorter amount of time than we had anticipated. Once the assembly was approved by the artist, we prepared the artwork’s surface for patination and applied chemicals to apply colour to the bronze. This specific piece has a combination of Antique Black, Cupric Nitrate, and Ferric Nitrate working in tandem to create a classic and rich patina which transforms the bronze making its surface mottled to look similar to stone. An advantage to such a patination is that it gives the artwork a monumental visual weight and gravitas by making the artwork look much heavier than it actually is or appeared before patination when it was a bare, light-coloured bronze. The timeline for School of Fish was
completed like clockwork. The pieces arrived at the shop, we inspected them within hours, and modifications were made. Over a period of two to three days the sections were already in the shell room. In stark contrast, we were working on another monumental artwork where the artist had given us their moulds from which to make waxes patterns. We were still able to make proper wax patterns to cast from the more traditional process, but it required significantly longer time and amount of labour that was not a component in the use of 3D prints for School of Fish. School of Fish was one of the largest
3D print to casting projects we have created to date, but it was also one of the most straightforward and time efficient projects as well. The control of pattern material and form allows for unexpected efficiencies to come forth which Artcast, Inc will consider for all future projects. This project has been an excellent proof of concept for us and should give all more confidence in the further value and development of the already available additive technologies in the use of casting. The future can only get brighter and more efficient in allowing for artists’ visions to come to life using such technologies.
August 2019 ❘ 13
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