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.
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. 😉
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To increase epoxy pot life keep the components cool and work in a cool room. Mix it in a cup then pour into a shallow lid or tray to keep it cool. Use a brush or a roller to apply the epoxy. Using a container for dipping concentrates the epoxy which speeds the temperature rise time and shortens pot life.
I like the cup with the pebbles, you could put it on the bookshelf and call it “art”.
Using a shallow lid would be nice, but for the dipping, air bubbles shall be able to rise. Tried this without success. Next time I will build a special cup in the exact shape of the board I dip into.