Quarter 2: Developing a Design and Fabrication Process
4.021, FALL 2018
In the second quarter of 4.021, rather than being given a material and told to design a product which fulfils a certain function, we were challenged to develop our own design and fabrication process. Through a series of translations, we moved from a 1D process to one which would produce a 3D form. We then analysed the properties of that product to determine a measurement that it could perform. These measurements could be based on a huge variety of things, from weight to the diffusion of light, to sound frequency.
THE "REVERSE" DESIGN PROCESS
The assignment we were given was to transform a 1D object, like string (which is close enough to 1D if you look at it from far enough away), first into 2D and from there into 3D. This is the basis of many design and construction methods, like using 2 by 4s to build a house, or yarns into textiles. Techniques we were presented with included the standard braiding, weaving, and coiling, as well as more exotic things like spanning tape between columns to create tunnels. In practice, we could also begin with planes, and shapes if our fabrication method demanded it, which could be transformed by folding, creasing, etc. I initially started off with chain-mail like arrangements, and exploding-toilet-paper-stars.
For me, the breakthrough came when I began messing around, quite literally, with hot glue. Initially my concept had been to use hot glue to create a base shape, and then fix it using an
aggregate, like sand. Perhaps if I gradually melted glue while piling sand on top, I could create a 3D termite-style construction. The sand, however, held the heat too well, and the glue didn't solidify in time to ward off the collapse of the structure. While the idea of using sand, a 0-dimensional object if you will, was cute, I had to go look for something else.
Water and Ice
That something I found in water. Where sand traps heat, water draws it away from the glue, transforming this material, which I had previously considered useful at best, into something truly remarkable. The molten filaments that had previously all flowed together were now held apart by thin layers of water and maintained their shape. Bubbles got trapped in the glue, and shapes began to form. Glue also has a curious property when you melt it into a fluid like water, which has a slightly lower density than itself. Only the topmost part will actually float, while the rest is forced under, allowing 3D structures to form.
It got even more interesting once I began thinking about hot melt (a more accurate name for hot glue) as possessing a shape in its own right, one which could be represented in this very clean fashion. It turned out that there were two ways that I could create an effective 3D structure. The first was by using glue as a mould. Since it solidifies when it's cold, I tried to spread it over ice, which created some fantastic shapes, some of which resembled baskets.
While this basket idea could have made my life much easier, as the "measurement" we had to take was effectively implied by the form itself, I took issue with this process for a couple of reasons. First, the shape of the ice pile, as well as the pattern of glue (a grid, as projected onto the x-y plane), were arbitrary and did not arise naturally from the process of melting itself. Second, it was too much of a metaphor for global warming (ice melting due to being covered with hot plastic? Yikes! Not sustainable.)
(If I had known before starting what a dreadful pain this decision would turn out to be, I might have stuck with the basket and the ice.) Hot melt, upon encountering water, has a second interesting behaviour I wanted to investigate further. I found that the glue strands would adopt starkly different local and global geometries when they encountered a fluid:
To understand why this happens, one must look at what actually happens with glue once it cools in a fluid. This is best demonstrated by studying the patterns formed on fluids of different densities, as shown below:
More dense Less dense
As one can see, in water, the glue forms a plane of coils which are gradually pushed underwater by the added weight of more glue.
In Simply Green, less force is required to push the glue under. While the glue still spreads out across the surface of the fluid to create loops, these occur on several planes, and the final shape is more three-dimensional.
Finally, with rubbing alcohol, the glue sinks straight to the bottom. Here it creates a small pile, much as it would on the surface, though it does not collapse as quickly because it cools faster when immersed in liquid.
To apply this to the disparity between local and global geometries of glue strands: surface tension causes melted glue to float. The duration of floating ultimately depends on the density of the fluid. As the glue is pushed out of the way by new material, it spreads out over the surface to form these loops. If the fluid is dense, the loops will stay on the surface for longer and bond into planes. Once these planes are pushed down by the weight of new material, there is a layer of water between the new loops forming on the surface and the old planes. Hence, several layers can be formed, connected by a single filament of glue. When one pulls on the glue, these separate out to long strings, as seen in the image above. (These can be many meters long).
Local: planes consisting
of tangled loops
Global: planes held together by long filaments
I was quite partial towards these strings. They fulfilled the assignment and arose from the process naturally. There were just a couple of problems: first, how do I present these such that the beauty of the individual planes becomes visible on a larger scale, and second, what... exactly... is this measuring?
On the first count, even I could recognise that the strings did not have huge potential as sculptural objects. The interesting part was too small, the global geometry was not super appealing. Also, the filaments were very fragile, so anything I made out of them would fall apart under its own weight.
Not that that stopped me from trying... (spoilers, they fell apart.)
Left, above: a possible, web-like arrangement
Right: gif of melting process
Since getting a computer to generate a vector for me would be a challenge, I chose to hand trace the shapes. I was then able to use that to design around that to a diagram of my process.
In order of decreasing depth. Note the larger bulb on the glue with the shallowest container.
For the next step, I had to figure out what exactly I could declare as "measurable". That meant gaining a better understanding of the behaviour of the glue, so for the next few weeks I experimented and iterated by changing every possible variable I could think of.
This included height, the temperature of extrusion, the temperature of the water, the depth, and the density of the water.
One of the more curious things I discovered was that that the size of that somewhat unsightly bulb at the top of the vector drawing (above) could be controlled by limiting the amount of glue which protruded above the surface. Once the glue was solidifying without fluid to support it, it formed a lump, as one might expect of hot glue. Hence, if one melted the same amount of glue in different depths of fluid, one might create different bulb-to-string ratios.
Different variables (clockwise from left: height, temperature, density) and their effect on the geometries of hot melt.
One particularly regrettable rabbit-hole I wandered down, shortly after I discovered how to manipulate the bulbs, was that of my aspiration to create "art". (I thought I had learnt my lesson years ago, but every time I try to do art when I should be doing design, it comes back to bite me.) Specifically, I had hoped to create a mobile or chandelier-like structure.
Below is a selection of images showing how just how poorly that particular experiment turned out.
Research, and journalling the process
It seemed like a good idea at the time. However, I had to admit to myself that this was not an appropriate way to treat the material. I was artificially trying to impose rules onto the glue which were foreign to its natural behaviour. Hence, I went back to the drawing board.
From line to plane to volume
The objective of the original assignment had been to translate an object in one dimension into three dimensions, so I retraced those steps. Using low heat, such that the string would be thick and not form loopy planes, I created a line.
With a slightly higher heat so that the contours would be visible, I returned to using ice, effectively draping glue over it, such that the resulting surface would, like a stiffened fabric, adopt the shape of the mould. The plane reminded me a little of a mountain, and curved inward slightly, causing me to wonder what would happen if I did the same, but for a closed volume?
The most natural geometry for a liquid to adopt is a sphere. Spheres have the least surface area for a given volume, so I reckoned they would be a good place to start. As we were nearing the end of the semester, Christmas decorations abounded. As a part of a plan to make the naturally produced volumes more visually appealing, I had ordered clear plastic baubles to encase them. Now, I repurposed them. Instead of being another separate system from the glue, I coated the sphere with the glue.
... now this had potential.
With and without supporting structure
Now that I had a presentation concept, I experimented with refining it. The most drastic physical change I had observed while making my measurements resulted from changing the temperature at which the glue was melted. This made sense: the viscosity of the glue necessarily depends on temperature, else it would be useless as hot glue. If it is cooler, it makes bigger loops, so the overall structure of layer on layer of such loops is less dense than if the glue were hotter when it impacts the surface of the ball, or surface of the water. (I also played with removing the supporting structure, but this just made the ball sag, and it was difficult to extract, in any case.)
Video illustrating variations in temperature
One thing I noticed as the structures grew increasingly elaborate and layered was that the uniform colour caused much of that detail, particularly the depth, to be lost. In order to alleviate this, I experimented with different ways of adding colour to the balls. The most obvious thing seemed to be to add colour retrospectively, which I did with food colouring. However, I found that, regardless of whether I dyed the water beforehand or drizzled food colouring onto the shape retrospectively, the colour would simply slip off the slippery plastic.
My solution was to use coloured hot glue. Since these are only available in a much smaller size than the glue sticks I had been using, I bisected them and melded them onto the primary glue stick. When exposed to heat, they would blend and create a coloured strand of glue which permeated and enhanced the structure of the sphere.
Comparison of different colouring techniques (dyed water, straight dye, bicomponent glue)
Video of bicomponent melting process
Note: while I had been primarily working with Simply Green, to create the final models, I used water. The colourless fluid made for more aesthetically appealing documentation, and the density was sufficient that I could create loops by allowing the glue to spread across the surface.
Timelapse of production method
Layers: clear, blue, clear
Credit: Isabella Hirt for 1/2 of the 200°C vector
Since I had these beautiful geometries, I was curious to see what the real-world implications would be. The thing that seemed most apparent to me was force of impact. Like the crumple zone of a car, I assumed that the springiness of the plastic tendrils would reduce the time over which collisions occur. Translated, this means that despite having the same mass, since I used the same amount of glue on both the 200°C and the 400°C sample, the 400°C ball, having no padding, would impact with a greater force. To verify this, I measured the deceleration with an accelerometer. (Acceleration is directly proportional to force).
The two downward spikes are the moment of impact. Remaining spikes are bounces of the ball and noise. As you can see, the area under the spike, which is known as the impulse, is the same. This means that the overall change of momentum was the same for both balls, which is to be expected for objects of similar masses impacting at approximately the same velocity. The interesting thing is that the 400°C ball has a much longer, narrower spike. The impact, therefore, took place over a shorter time span. To keep a constant impulse, the acceleration, which can be considered proportional to the force, was greater.
Translation: if you have the choice, don't get hit by the 400°C ball, get hit by the 200°C ball. It will hit you less hard.
BONUS WORK (GLOWBALL)
In order to conclude the saga, I wanted to apply everything that I had learnt to make one final product. This included using different temperatures to create balls of different density and structural integrity, interweaving the blue lines of glue to bring out structure, and using the surface tension of water to enhance natural geometries and coiling behaviours.
Rather than starting with a preexisting plastic bauble, I made this ball from scratch, turning glue until I had a spherical base I could build off. Working in layers (of low temperature clear to create form, low temperature blue to bring out the form, and high temperature to consolidate structural integrity), I gradually constructed a melon-sized sphere. Because there would be a much greater depth of complexity in this final piece, I also chose to interweave string lights, which were thankfully waterproof, to highlight the structure from within.
A FINAL NOTE
This project was quite challenging for me. I got quite flustered about midway through, as the whole time I could see that there was potential in the fabrication process, but I could not figure out how to visually express the weightless, beautiful qualities that I saw in the strands of molten glue in such a way that other people could see it as well. It will forever amuse me that, even as my deadlines approached, it was Christmas and the festive decorations of the season that solved my problem. By exposing me and the people I consulted to objects (baubles) that I would not otherwise have considered, I came up with new ideas and new methods. It just goes to show that inspiration can come from anywhere.