Every morning when I get up, I use this coffee grinder to grind beans for my morning coffee.
When I remove and subsequently open the top of the bin, I often find that enough static electricity has built up in the grounds/bin that particles of coffee will literally fly out of the bin and onto my hand and the counter, making a mess. Coffee will also be stuck to the sides of the bin to varying degrees, making it necessary to rap the bin on the counter in order to dislodge the particles from the sides. Of course, more then fly out and increase the mess on my counter.
I have made some observations of a few factors that seem to affect this:
- It happens to some degree with most beans, but I've noticed that the darker the roast, the greater the static charge. It's the worst with French Roast (my favorite), which is also oily since they add oil to the beans in the roasting process.
- The coarseness of the grind doesn't seem to matter except that a coarse grind produces heavier particles which don't tend to fly as far.
- Cleaning the bin had no observable effect on the static.
- Waiting a while after grinding doesn't seem to do much to alleviate the problem. I've ground the beans and waited 10-20 minutes before removing the bin and observed no apparent decrease in the amount of static.
- It is worse in winter when the air is dry, but I don't really let my house get too humid.
- Google reveals that this problem is not specific to any one brand or model of grinder, but seems to plague most burr grinders.
My questions are these:
- What is the cause of this static charge in the grinding process?
- What modifications can the end-user make to either the grinder or the process to prevent static buildup?
- How could this be eliminated in the design itself?