Currently I am working on the coating for the foot part of the plant watering sensor. Here I already tried a wide range of techniques and materials. At the moment, epoxy seems the perfect material choice – so I am trying different resins and hardeners to get the best results.

Some hardeners are very reactive and produce a very strong exothermal reaction. While I read and prepared everything meticulously for a new process as usual, I still get sometimes very bad surprises.

For the process, I dip the foot parts into the epoxy resin and hang them up for drying. To waste as few as possible epoxy resin, I used very small plastic cups for dipping.

The exact material of this plastic cups is very important I learned. You should never use something which will react violently with the mixed epoxy resin, as you can see in the next picture.

lucky-resistor-1

The cup literally started burning after a few minutes and I had to drop it outside on the forecourt to prevent any disaster. In the picture you can see the remains of the process: A beautiful frozen epoxy block, in the middle of the melt down. The cold air outside rapidly cooled down the process, so the burning stopped.

Mental notes for the next experiments:

  • Use only cups where you exactly know the material.
  • Keep a stop watch running with the pot time, assume 20% shorter time as specified.
  • Prepare an evacuation/meltdown plan. 😉