The paper I chose to read was, Designing a Sustainable Material for 3D Printing with Spent Coffee Grounds, by Michael L. Rivera, S. Sandra Bae, and Scott E. Hudson. The purpose of this paper was to discuss the use of Spent Coffee Grounds for prototyping and experimenting in 3D printing driven by sustainable practices. According to the research paper, “…though energy consumption is the largest driver of 3D printing’s environmental impacts, material choice can significantly reduce the amount of energy used if the material can be printed without heat. Material choice can further reduce environmental impacts if its components are non-toxic, abundant, renewable, and compostable,” (Rivera, Bae, & Hudson, p. 295). For example, a common thermoplastic used in 3D printing, PLA, often ends up in landfills and are known to take up to 100-1000 years to degrade. Even though PLA can be recycled and reused as printable filament, this option poses issues with resource accessibility and becomes very energy extensive.
During the project discussed in the paper, the authors wanted to design and discover sustainable material and resources that were accessible and attainable to the general public. Ideally, the goal was to find and work with material that can be printed without heat, is renewable, is non-toxic, is primarily produced from local waste, and is compostable. With that being said, the material choice for this experiment was Spent Coffee Grounds (SCG), which avoid thermal energy consumption; are recyclable and compostable; and are easily made and accessible within our own home. In order to work with SCG, 3-4 other components were used; Carboxymethyl Cellulose, Xanthan Gum, water, and occasionally Beeswax. These subsequent materials were chosen, because: Carboxymethyl Cellulose is a biodegradable water-soluble polymer (serves as a binding agent for spent coffee grounds and increases viscosity for printing); Xanthan Gum is completely biodegradable and prevents spent coffee grounds from separating out of the mixture and increasing its viscosity and degree of shear thinning; water is used to combine all components; and Beeswax was explored as a coating for these objects to prevent dissolution (may slow down biodegrading, but is still known to biodegrade within two weeks). Since prototyping with 3D printing often leads to wasted material, it’s important that these objects can be recycled back into printing material, also in a sustainable way. Some examples of prototyping used with SCG for this specific paper was ornament necklaces, planter pots, and compostable expresso cups. This workflow was tested by initially printing the object using the SCG, degrading it back into printable material using a coffee grinder, and re-printing the object again. During this process of test printing, it was also discovered that there were slight errors in the length, width, and height (all below 2%) in comparison to the PLA printed versions.
Some other challenges that were observed were: dry and printed spent coffee ground material was considerably weaker than PLA (tensile strength); it exhibited less control during 3D printing in comparison to engineered thermoplastics; and may result in shrinkage (though this may be seen as a negative thing, it could allow for control over working with biodegradable shape-changing interfaces). A few other challenges and constraints that came up were: unlikely to achieve the same level of quality (surface defects but no impact to overall function) with SCG in comparison to thermoplastic material; concerns regarding longevity since spent coffee grounds are meant to be biodegradable over time (though a positive quality for purposes that are designed to be temporary); may take a while to dry and is known to shrink, causing frustration to users (shrinkage can be mitigated by scaling objects prior to printing); needs to be printed on a relocatable substrate and becomes difficult to print large overhanging parts since previous layers don’t tend to be as supportive; and as previously mentioned, these prints to tend to be more brittle and weak. This paper co-authored by Scott Hudson provides great insight and research into not only experimenting with different materials in 3D printing, but also finding sustainable materials and methodologies that aren’t hurting our environment meanwhile being easily accessible to the general public.
The colloquium talk focused on the future of computing power in human computer interaction. Scott Hudson uses the concept of Moore’s Law (where computing power is expected to double every two years) and the notion that almost nothing has happened yet. He adds that everything that is going to happen is still ahead of us and that we are only at the beginning of this law. I believe his second and third exemplars from the colloquium best relate to the paper I chose to read. In the second exemplar, we are eventually led to ponder about interactive devices where user action reconfigures an antenna printed on paper (how do we make them and interact with them). Scott Hudson introduces the third exemplar as a new capability of making the world rather than just “bringing information into the world.” Some examples of this can include experimenting with new types of materials or new types of printers. Now going back to the paper, he discusses how working with conductive and shape-changing material, “could enable creating impermanent devices that change their shape or sensing functionality as an indicator of their biodegradation. Such devices could support applications in HCI that extend to wildlife sensing and agricultural monitoring. With HCI researchers continuing to develop and explore new smart and morphing materials, we believe there is a huge opportunity to design a new generation of materials that are functional, sustainable, support prototyping, and enable the creation of interactive devices,” (Rivera, Bae, & Hudson, p. 307). Since in the colloquium, the future of 3D printers involve knowledge around how functional objects require skill, using sustainable materials for prototyping would be the greatest way that sustainable material use can support extended research in HCI.