How to Reuse Your Old Coffee Grounds for Fabrication

The focus of this work is to highlight and call into question our relationship with materials. To explore the everything between the seemingly banal or complicatedly rich interactions with materials which comprise our built environment and larger footprint on this world. The goal of this instructable is to highlight a material waste [ Coffee ], of which most of us have a personal existing relationship with, through exposing the process and physical products of such an inquiry. If nothing more, you can learn a lot about working with coffee as a material for fabrication!

In 2011 alone, we produced 8.7 billion pounds of coffee grounds as the second most traded commodity in the world, next to oil. To get an idea of scale – if we were to replace the Empire state building’s concrete with coffee, we could could build roughly 2100 Empire State buildings in a year. Perhaps it is because of our detachment with coffee, as commodity for consumption rather than plant and bean, that we often perceive coffee as material waste. So where do you get used coffee grounds from?

You can start your own compost at home and collect the grounds. Or Go to any Cafe and ask them if you can take the grounds off their hands. Most Cafes already store the used grounds from espresso and drip in its own bag for clean and easy disposal.

Please remember that used coffee grounds will mold. Coffee grounds are an extremely porous material and collect a lot of water. For this reason, if you leave them out for too long or collect old grounds (3+ days), it is most likely that your grounds will begin to smell and collect mold.

So what do I do with all these grounds after collected, one might ask? Well they are going to need further processing before you can use them well! As a note, the coffee grounds are already a highly processed material. They have been picked, dried, packaged, shipped, cooked, ground, and filtered. But there is still more to do.

Most likely your grounds will still be wet from previous use, now its time to dry them for further use. The quickest way to dry the used coffee grounds is in an oven, set to bake at about 400 degrees F for 15-20 minutes. Make sure to keep an eye out as they are liable to toast and burn. The goal is not to burn your grounds, but to dry them. An alternative method is to put them out in the sun for as long as possible to achieve a dryness.

Once the grounds are dry, there are many possibilities for working with such a unique material.

Ok, so now you are probably wondering, what do I do with all these grounds?

Well it depends on what your application is, what material qualities you want to achieve, or simply what your interests in exploring are. My own personal is primarily architectural and spatial thinking - how we might build things and what spatial conditions they might create. With this in mind, I chose to explore and research the use of coffee with Mycelium, Polymer Composites, and 3D Printing.

Each fabrication process creates a completely different material quality. As previously mentioned, its important to think about what you would like to achieve through use your material. In such a way, if you are to think hard and listen to your material, the material might inform and inspire you in ways not previously imaginable.

Thats right, grow mushrooms with your used coffee grounds! Mycelium needs organic matter to eat and grow, and used coffee grounds can provide the nutrients needed. To do this you will need (1) used and sterilized coffee grounds, (2) Mycelium, and (3) form work.

There are a couple ways to start Mycelium growth, however buying a starter kit is best to speed up the Mycelium growing process. I like to use Ecovative GIY "Grow It Yourself" kits, these guys have engineered their Mycelium spawn to grow super fast and be super resiliant. It is important to remember that Mycelium can be easily killed by mold or bacterial growth. That is why it is important to process your coffee grounds before hand in order to kill any previous mold or bacterial growth. Please research and read any instructions that might come with your Mycelium starter kit and remember to lather EVERYTHING in Lysol or Alcohol to sterilize and clean.

Once your kit has grown, or arrived grown, break up all the Mycelium into a mixing bowl. Once the Mycelium is broken down, mix about 32oz of roasted and sterilized coffee grounds into the bowl. Now it is time to put your Mycelium+Coffee mixture into its form work so that it can grow. The form work will allow the Mycelium to expand in such a way that it will fill the entire form. Make sure your form work is sterilized too! The Mycelium+Coffee will now need to sit in a dark, warm (not cold), and semi humid environment for 5-8 days while it grows. Once grow, the form work should be removed and your new Mycelium+Coffee object should be put in the oven and baked at about 200 degrees Fahrenheit until dry. The result should be a form or object made from Mycelium grown from used coffee grounds!

Fabrication and architectural applications include biomass infill, unique insulative solutions, as well as living or filtering architectural componentry. More specific process and documentation on Coffee+Mycelium to follow in additional instructable.

Coffee grounds, as a material, are great biomass for use in casting processes. The coffee grounds have a great insulative value, a unique and efficient molecular packing ability, and are readily accessible in great abundance for fill and use!

In addition to these material qualities, the used coffee grounds also provide a smooth and almost velvety finish when CNC machined as well as translucent properties when cast. My work explored these material properties through a series of casting and CNC milling studies on the 5-Axis DMS. I found that it takes great consideration and tests to figure out the correct ratio of coffee grounds to resin in order to achieve the desired effects of translucency, texture, and strength. I focused on using epoxy resins, however polyester resins work great too.

Such a material process would work great in architectural exterior/interior conditions of paneling for facades, feature walls, as well as any other sort of cladding conditions. More specific process and documentation on Coffee+Polymers to follow in additional instructable.

Perhaps one of the most interesting and difficulat applications in reuse of coffee grounds, 3D powder printing is a process which works great for fabrication. Any fine powder can be used in a 3D powder printer, however its important to achieve a powder consistency below 50 microns (think powder sugar). Grinding the used coffee grounds turned out to be one of the most difficult tasks. Luckily I was able to find a supplier who extracts the oils for used coffee grounds, to use as fuel for energy, and is left with a finely ground and desiccated waste coffee powder. Perfect for 3D printing!

Further material considerations and studies were required in figuring out powder binder solutions, machine settings, and post processing. I prefer using the old Zcorp 310 powder printers as they are easy to load and unload ones own powder as well as hack the machine for various settings. The results were impressive in the final printed objects strength, texture, and other material characteristics! While this process may not be accessible to all individuals, it is a technology that is rapidly becoming more advanced and accessible as time goes on.

The technology of 3D printing with reused coffee grounds works best for objects that cannot be produced in any other way, at least with ease of fabrication. The technology works best when it is used to print individual and unique parts rather than to mass produce the same object. In such a fashion, architectural facades/walls/forms broken down into unique tiles and pieces is a great application for 3D printing reused coffee grounds. More specific process and documentation on Coffee+3D printing to follow in additional instructable.