CASTING A CHAIR : FROM SKETCH TO PRODUCTION
MATERIAL AND EQUIPMENT LIST Plaster Wood/chipboard (has to be smooth and cut to size) for base Threaded steel rods (12mm diameter) Silicone Mould Terracotta Clay G4 Damp Seal MDF board (to lasercut the positive out of) Laser Cutter SIlicone melting pot Plywood to make a frame with Nuts and bolts (12mm) Washers (12mm)
GLOSSARY CAD. Computer Aided Design (in this case Google SketchUp). Cast. The repeated copies of the original positive2 made from plaster. Lasercut. A technology that uses a laser to cut materials, and is typically used for industrial manufacturing applications. Module. One of the 16 units out of which the chair is made. Mould. A negatiive1 space medium through which a positive2 is cast. Negative. The space left by the positive where the repeat casts5 are formed. Positive. The original module3 used as a template around which the mould4 is formed. Precedent. The subject of research study for the project. Scrim. Reinforcing fibers used to strengthen setting plaster Threaded Steel Rods. A steel rod with a zinc coating with a crew thread to allow nuts to be screwed on. The one used in this project is 12mm in diameter. Vinamold. A type of organic silicone found in many shops
ACKNOWLEDGMENTS Mark Sowden
INTRODUCTION Traditionally chairs are made from wood, metal and (more recently) plastic. It is not to say that experimentation with materials have not taken place in the past. Far from it! I am not the first person to be doing this and I, certainly will not be the last. However, these experiments with materials have mostly been carried out in other facets of the design industryâ€”be it architecture or furniture designâ€”but not so much within graphic design. Again, this is not to say that I will be the first to do so and in many cases it will not be relevant at all. After all, it is hard to find a communicative justification for designing and building a chair for graphic design! However, due to the nature of the project, I believe that the chair does act as a medium of communication. The interactivity of the chair itself provides for a method of information exchange between the user and a digital world.
CONCEPTS AND PRECEDENTS The development for the chair started very early. The start of the development process saw the chair being of a more conventional shape—a solid piece of cast concrete supported by studded legs. However, the further I developed the idea the more apparent it became that the conventional chair was not justified. I had to stop looking at chairs by Charles Eames, Eileen Gray and Ludwig Mies Van De Rohe. Those chairs would not form a good precedence for the design because they do not appeal to communicative design. They are spatial designs. They take into account the vernacular of a well-lit space. It didn’t agree with the goals of what this project set out to explore—i.e. the connection between the physical and the metaphysical. Therefore, something more modular would be better suited as a precedent. The question was raised as to what would be a good modular precedent to form a design on? This project is all about how an individual (user) interacts with the space around them (be it physical or digital). Therefore, it would be logical to look at the human body to solve this—in particular the very part of the human body that is responsible for supporting and dictating the chairs that we sit on—our spine!
Opposite page (top)—The Eames fiberglass chair was one of my first studies. It was an idea that I had fantasised about. This is a piece of design that all designers have idealised at some point. Opposite page (right)—This Eileen Gray chair does not follow the conventional rules of having a symmetrical shape and the ideology behind it is bold and daring. Opposite page (left)—Ludwig Mies Van De Rohe is often considered as being the personified epitome of modernism and this is reflected not only in architecture but also in the fact that he was multidisciplinary. The chair is something that idealises that.
1. The first precedents and concepts were leaning towards things that already existed. Chairs that looked like a pastiche of the Eames fiberglass chair. 2. & 3. The design started to progress in terms of the actual shape and the playfulness of the materials used was also starting to be reflected in this design. For example, the pieces of steel rods that would hold together the concrete was starting to be considered along with the blocks of concrete that had to be cast. However, it still looked like a pastiche of an already existing modernist chair.
5. 4. Initial module design–The initial design of the module came in the shape of an “A”. These modules would be repetitively stacked on top of one another and be held together using a frame of some sort (at this point I have not yet considered the frame yet). The modules allow just the right amount of movement between them to form a gentle curve (theoretically) comfortable enough to sit on. These modules will be made of concrete and will weigh quite a lot. Maybe the materials need to be reconsidered. 5. A study of the human vertebrae. This study started to change the precedence of the design. It was this very study that started to make for the beginnings of a chair. This study made me think about the idea of how our body (especially our spine) works because of little modules. Rather than something that it set and stiff, it is formed of smaller blocks held together to produce a bigger and more fluid and flexible unit. Why couldn’t the chair I designed be like that? This is when I started looking at modules that slotted together to make a bigger and more cohesive unit.
FROM SKETCH TO CAD The next step was to lift the design from the sketchbook paper and into a digital 3D environment where I would have a much better visual idea of what the modules would look like and how they would function without having to actually make it in a 1:1 scale.
6. The first step to working in a three-dimensional environment was to reconsider that which was already considered working on paper. This shows how the design of the modules were refined and an exact measurement for the modules was worked out. All the sharp edges were also refined to make a more curved module. Scale—1:4 7. The modules were now starting to be considered truly in three dimensions. Scale—1:4 8. & 9. The modules at this point were being considered not just singularly but also in relation to one another and how they would all fit together. This helped further the design a lot more because they were not just singular objects any more. They had full form and a visible function. Scale—1:10
At this point the “chair” itself was starting to take shape. Of course it wasn’t assumed at this point that the chair would be staying this shape. It still had to go through many consultations and tests. However, at this point, the general shape of chair had started to show and would probably remain. However, there were still many details that were still left unconsidered—such as, how would the chair stand up by itself? What kind of a frame is right for this chair? Is concrete really the right material to use? Many doubts still existed considering the reality of the chair. A consultation with an expert was due.
FROM CAD TO CONSULTATION This is probably turning out to be a pretty boring read but let me assure the reader that doing it is a lot more interesting than writing/reading about it. A lot of the aspects of the design of the modules have changed since the consultation with an expert in casting and moulding.
10. After consulting it was decided that the hole that would form the structural support for the module to be supported on would have to be moved down a little bit so as to be more structurally sound. Scale—1:4 11. It would also be elongated and would now be formed of sixteen long modules (600mm in length each). This is to avoid unnecessary casting and also to make it more comfortable to sit on. Scale—1:10 12. & 13. You can see how the consultation affected the whole design. Scale—1:10 14. At this point I also started to produce renderings in order to see how the chair could look physically.
14. The development in design is something that is inevitable and should be accepted as a part of design itself. There will be many things that evolve and sometimes you even have to revisit ideas that had been previously discarded.
FROM CONSULTATION TO CAD Now that I was approaching the finality of designing the modules for the chair, it was time to start thinking about the frame for the modules. I had in mind a steel frame what would support concrete modules so that overall the chair looks very industrial. I suppose, I was trying to challenge the preconceptions about the notions and use of certain materials (like steel and concrete) in designing something like a chair. 15.
15. This sketch shows further development of the design. It has now progressed into a more final aspect. It was decided that rather than have a hole through the middle of the module (which could weaken the structure) it would be a better option to cast threaded steel with the modules themselves, thereby, strengthening the structure. It was also decided that rather than casting the modules out of concrete, Herculite plaster would be used. This reduces the time it takes for the modules to dry and be used. 16. & 17. A frame for the chair was also taken into consideration. It was unfeasible to produce a steel frame as it would cost a lot of time a money. Therefore, the frame would be made from plywood and would be fixed together using the modules.
CAD AND CUTS (LASERCUTTING) Having finalised the design for modules, the next step was to prepare a positive for the mould to be cast. The first step would be to prepare a CAD file that could be exported into Adobe Illustrator so that I could print an accurately sized drawing from. At this point I didn’t change the design with the hole as it would only add to the work but rather use the hole as a guide to cast the rod in. Once the CAD file was printed the initial method to produce the positive was to make a hollow shape for the module out of grey card. However, this method was fraught with problems since it would be impossible to make precise and accurate cuts to produce a positive. It was also going to be problematic to produce the curves within the model. Therefore, I decided to lasercut a hundred sections that measured six millimeters in thickness and stick them together. This would form the main positive for the mould. 18. 18. & 19. The illustrator file and the lasercut mdf board.
20. The final positive that has been lasercut and put together. The final positive consists of 100 pieces measuring 6mm each making a total height of 600mm. This will be the width of the chair. There are a few issues that have to be taken into consideration when putting the pieces together— the most primary of them being that unless a guide is used the pieces will not stack up perfectly. This is what has happened with the positive. I have decided to keep this ‘mistake’ because it adds to the organic nature of the chair.
RAMIFICATIONS OF CASTING
Top (left)—The remnants of the silicone that burnt and released fumes. It is important to remember that it does release quite a pungent smell and it is advised that it is used in a space with proper ventilation/extraction. This was the first attempt at creating a mould and it was not successful. It was decided after this that it would be cast in a proper casting workshop. Top (right)—The two pots that were ruined from melting Vinamold at home. You have to be very careful if ever attempting to melt silicone using domestic utensils. The temperature has to be just right and once it goes over a certain temperature it might start to burn and produce unpleasant fumes. It will also stick to the container that is used to hold it in. Also, a thermometer might also break if a proper one isn’t used.
CUTTING TO CASTING Due to the positive being quite long it was decided that the mould would have to be cast in two parts. The method would be to use as little vinamold silicone as possible (enough for it to be stable to pour the plaster in). The mould will be made in the following order:— 1. The base and the positive for the mould will be wrapped in plastic (this helps the clay separate from the positive and will form the space that the mould is poured into). 2. Clay is then layered on the sides of the positive and patted down so that it seals the positive. Dovetail grooves made of clay are also put onto the edges of the mould so as to hold the rubber mould in place when it is finally poured. It is also important that a pile of clay is placed on top of the clay “jacket” to create holes for the mould to be poured into once the clay is off. 3. Plaster is then layered on top of the clay while it is setting. Scrim is cut to size and mixed with the plaster and added to the layer to reinforce the plaster jacket. 4. Finally, the clay is removed and the mould is poured into the resulting space. This is done in two parts are put together to make one mould. 21.
21. The image shows how the mould is created using a slightly more laborious but correct way. Making the plaster jacket alone can take up to seven hours. The melting of the silicone can take up to an hour for each of the part. Therefore, creating the actual mould itself can take up to ten hours. It is important that this process isn’t rushed because the finished modules all depend on this one piece being correct. 21a. Plaster Jacket 21b. Clay 21c. Positive 21d. Negative Space
22. The inside of the plaster jacket after the clay has been removed. 23. The mould preparation showing the layers (positive at the top, clay in the middle and the plaster jacket at the bottom). 24. One of the grooves to hold the silicone negative in place. 25. The plaster jacket taken off from the top with its clay removed. 26. Cleaning the mould after removing the clay. 27. Adding a clay lip to the holes in the plaster jacket where the silicone is going to be poured so that they do not spill out of the container. 28. Melting the vinamold silicone. 29. The poured vinamold silicone cooling off after the lip has been removed. 30. The set vinamold rubber on one side and getting the other side ready for the same process.
CASTING THE POSITIVES With the mould now complete, it was time to start casting them into new plaster positives. The plaster used for this process is Herculite No. 2. This is a stronger type of plaster that bonds and sets stronger than other types of plaster like fine casting plaster. It is also important to remember that the two halves of the moulds have to be perfectly in position in order to avoid the wet plaster spilling out of the sides. A base will also have to be fixed so that it allows for the mould to sit tight. The base will also have to have three 12mm holes in them. The two on either sides will fix the mould to the base using a hex nut and bolts and the one in the middle is to allow for a threaded rod to pass through. This 12mm threaded rod will be fixed to the base board using a hex nut on both sides of the board and a washer on the underside of the board. One of the hex nuts will become a part of the module when the paster is poured. 31.
31. & 32. Mixing the plaster. To get the right consistency you have to wait for the plaster to settle and then pour out the excess waster until you get to the thick mixture. Then mix with hand to get rid of lumps and pour into the mould. 33. The mould as it stands up to take the plaster. 34 & 35. Pour the plaster to the brim of the cast. Tap it gently to remover any air bubble and leave to set for about an hour. Then, remove the mould gently and take the set plaster positive out. Make sure you unscrew the bolts for the base before you remove it. When you do have to recast make sure you clean the mould properly otherwise it may not be a tight fit.
MAKING A FRAME The frame is simple. It consists of two 18mm thick plywood with the dimensions of 1220mmX950mm. This frame contains 16 perforations that the modules slide into. Once the modules are in, they are then fastened with nuts that is tightened flush.
An introduction to casting a chair.