Conductive Paint Art
Skills: Rhino, CAD, Laser Cutting, Design, Testing, Prototyping, Excel
Role and Background:
This was a personal project that I did after I was gifted conductive paint as a birthday present. After thinking of ways to use it, I decided that I wanted to make an art piece using the paint that lit up LED lights. Now I’m not very good at painting, so I decided to laser cut the outline that I wanted to make and put the paint in that. And because I was going to be using a fair amount of conductive paint, I decided to learn how to make my own.
I also entered this project into the 2017 Maker Summit competition, and won under the category “3D printing and Laser Cutting”.
There were multiple challenges that had to do with working with the conductive paint since documentation on it is pretty sparse. While doing the project, I needed to figure out how to make my own paint, make sure that the paint could carry enough current for what I wanted to do (because the paint has a resistance), create a circuit with the paint (without having any short circuits around the LED’s), and determine how to get the paint into the laser cut pattern I made without making too much of a mess because the paint mix that I ended up using had a high viscosity (it was closer to paste).
Making and testing the paint: After researching DIY conductive paint, I determined that the best recipe for me to use involved acrylic paint and graphite powder. After ordering the materials, I found out after my first attempt that the graphite powder that I got had flakes that were too large (it wouldn’t carry a current). So I had to order more graphite powder that was finer, and my second trial did work.
When testing the conductivity of the paint, I tested three different ratios, and compared them to the control (straight acrylic paint) and the commercial brand paint that I got for my birthday. As expected, as the ratio of graphite powder to acrylic paint increased, the resistance of the paint decreased. Increasing the ratio also had the secondary effect of increasing the viscosity of the paint and making the paint slightly grayer.
With the results I got from my experiment I next went to excel to help me figure out if the project I wanted to do was possible, and if so, how many LED’s I could use and how large I could make my project (if the path is too long the LED's won't light up). To start, I found out the voltage drop and current usage of the LED’s I wanted to use, then chose a battery set-up (4 AA’s in series) to further constrain the problem. From here I varied the path length (size of my project), resistance of the paint I was using, and number of LED’s I was using until I came to a solution that I believed would work.
Designing, Laser Cutting, and Assembly: Once I confirmed that the idea would work and had a relative idea of the size that I could make it, I went to creating the design in Rhino. I had an idea of what I wanted to design (essentially a tree with circuit roots). This design had the advantage of having all of the LED’s in parallel, with the LED’s (mostly) equidistant, which made it easier later on to make all of the LED’s the same brightness. To create the design, I found images online similar to what I wanted, which I traced in Rhino and then merged together.
With this done, I needed to create a complete circuit with the paint that couldn’t have any “short circuits” that would skip the LED’s. I achieved this by creating a design that had 3 panels; the first panel was the design that would be seen in the front, the second was a solid sheet in the middle, and the 3rd panel finished the circuit on the back. To complete the circuit, I drilled holes at the location of each LED, which acted as the bridge between the front and the back, and I also drilled a hole through to the center of the front piece which connected the front side to the battery pack. Since the circuit on the back panel didn’t need to be artistic, I made the paths wide to minimize resistance, and would allow me to use the backside to manipulate the resistance later (by adding and removing paint) to get all of the LED’s the same brightness.
Once the design was completed, I laser cut the parts out. Then I stained, finished, and glued the sheets together.
Adding the Paint: Next was getting the paint into the laser cut outline. This was difficult because the paint was very viscous and the paint needed to be applied thickly. After problem solving, the solution I came up with was putting masking tape over the laser cut outline (to minimize leakage, and applying the paint using a syringe. Even this solution wasn’t perfect, and required some post-cleaning using rubbing alcohol to wipe off any bleeding of the paint onto the surface.
I then added paint to the back, but not as thick as in the front, so that I could later add paint (decrease the resistance) to modify the brightness of the LED’s.
The final step was adding the LED’s and battery pack to complete the surface. All of the LED's litup the first trial, but varied in brightness, so I needed to go through a couple iterations of adding paint to the back until all of the LED's were close to the same intensisity.