By Kyle Anderson, Baratza Co-Owner and Engineer
Static: the grossly misunderstood and (still, to this day) hotly debated phenomenon that plagues many facets of our lives but can REALLY (randomly) irritate those of us who grind our coffee beans daily.
As recently as mid 2011 there were breakthrough findings about the root cause of "static charges" that shatter the commonly held paradigms of what causes static. About the only remaining principle that survives from the old paradigm is that friction is a key ingredient in creating an imbalance of electrical charges, which shows it's ugly face as "static". The grinding of coffee in a burr grinder unavoidably includes a lot of friction - friction between the beans and their resultant particles, as well as between the coffee and grinder materials. In the presence of friction, dissimilar materials and non-uniform-shaped particles, the possibility of static rearing its ugly head, is ripe. Add to this, low humidity (Midwest in winter or Phoenix in the summer), varying degrees of moisture in the roasted beans, flooring and countertop materials and (yes) even the clothing and shoes of the grinder operator, and we have more variables than we can control.
At Baratza we sought out the advice and wisdom from people who spent 30+ years working with (or against!) static electricity issues. We've discussed and tested all-metal grinding chambers, grounding of the actual coffee powder, grounding of the coffee bin, and on and on - more crazy ideas than you'd care to know. We have also confided in most of the world's commercial coffee grinder manufacturers and they all have expressed the same frustration with the randomness with which static shows up. Not one grinder manufacturer has found the panacea to eliminate this messy headache. Though the experts may not agree on all the contributing factors that cause static, there is agreement that the best way to manage the static is through Electrically Dissipative Materials. At Baratza, we use IDP (Inherently Dissipative Properties) plastics for transport and receiving our ground coffee powder. These dissipative materials "bleed off" any charge, in a much better way than conductive materials (i.e. Metals). IDP plastics cost 4X what standard plastics do, but we feel it is money well spent. Unfortunately, the coffee grinder gets blamed for causing the static mess that people encounter (because the whole beans showed no signs of static), but the same grinder, in the same room, at the same time, with different beans can show no signs of static, so is the fault that of the beans? There are myriad work-arounds shared by many to minimize or eliminate this messy problem. Probably the most universally effective is to momentarily increase the humidity of the whole beans just prior to grinding (this is fancy talk for spray a LITTLE water mist or droplets on them). Obviously, this only works if you have a small quantity of beans in your hopper, else the beans on the bottom get no water.
In summary, grinding coffee beans is an activity that occurs in a system made up of numerous uncontrolled variables (varietal of bean, degree of roast, freshness, humidity, temperature, etc). With the best grinder technology and some variables in your favor, you will have minimal to no static issues. If a few too many of these variables stack up against you, then you are bound to see a static-ee mess, to some degree. When you encounter static, we encourage you to wait 15-30 seconds after the grind has completed to allow the charge to bleed away, then tap the side of the bin and all the grounds should fall into the bin.