Un-static-ing plastic

Last year I bought myself a good but inexpensive automatic burr grinder for my coffee.  It grinds from a hopper on top down into a plastic cup in the bottom.  hit a button, wait 20 seconds, pull out the cup and dump into the filter or french press.

The plastic cup is super-static-y, and when you try to dump the grounds in the filter, your hand, the countertop, and everything else gets covered with ground coffee.  I tried hand washing, dishwasher, I even sprayed it with static guard which worked until I washed it off.  I thought about replacing the cup with something else, but it's very specific in design.  It has a cover and a little chute that lines up with the outlet of the burr.  It also has a safety switch that it won't grind unless the cup is in place.

I'm guessing that something about the grinder itself is charging it.  I've learned to deal with it.  Having wet hands helps a bit.  So this isn't a real "how do I fix it" thread, more of a "let's discuss static and maybe I'll learn something" thread.

In reply to Curtis73 (Forum Supporter) :

Two prong plug or three?  My first thought admittedly not fully awake is convert the grinder to three prong plug and ground the chassis if there is one.

2-prong.

I have a feeling it's all plastic except the motor and the ceramic burr.  Still worth a shot.  I could try it with a wire screwed to something and jammed in the ground hole of the plug.

I'm thinking about sawdust dust collection systems...

When using plastic or PVC pipe, the friction from the movement of wood shavings through the pipe can create static electricity which can cause a fire. To reduce the risk, we run a copper wire through the pipe and ground both ends.  
 

Maybe something similar in the top hopper of the machine?  Perhaps just a grounded copper wire loop through the hopper (avoiding grinding blades).

Wild assed guess.

Back when Ethyl Corp's Visqueen Films Division was still making polyethylene sheeting in the States, they would drape a conductive tinsel that looked just like the stuff you'd wind around your Christmas tree across the moving plastic sheet.  Presumably, it would conduct any accumulated charge through its wire core to ground.  The act of grinding coffee beans results in the grounds whirling around inside the plastic cover which, much like shuffling your shoes across carpet, collects a static charge.  This time of year, I'm guessing the air in your domicile is extremely dry.  Adding water vapor to your air via a humidifier may be the most effective way to remedy the problem.  Or you could try rubbing it with some conductive tinsel. 

In reply to SV reX :

Easy to do and worth a try. 

I have also been involved in static discharge through plastic pipes and tanks. These were oil well pump lines and plastic tanks used to collect well pumped oil and waste water which where exploding from accumulated methane gas. They had to put continuous grounding wire inside the pipes and tanks. When they used to be all metal, they where self grounding. I agree on trying to ground things with a third ground wire plug.

The design makes it a little difficult to access the hopper or the cup, but I suppose a drill could fix that.  Maybe stab a coil of solid THHN down through a 1/8" hole in the top.

In reply to 1988RedT2 :

No real whirling.  They don't really move.  It's a burr grinder, so think more like pepper mill instead of the old school spinning blades.

Curtis73 (Forum Supporter) said:

In reply to 1988RedT2 :

No real whirling.  They don't really move.  It's a burr grinder, so think more like pepper mill instead of the old school spinning blades.

Ah, yes.  I looked back at your picture and I saw that it wasn't the whirly-type grinder I have, but rather a burr-type--consistent with your standing as a sophisticated gentleman and drinker of well-brewed coffee.  Regardless, you still have some movement as the coffee falls into the hopper.  I maintain that grounding done to the motor will have little to no effect on the static in the coffee hopper.  However, as my wife is fond of telling me, I have been wrong before!  And besides, being well-grounded never hurt anybody.

I have the same problem, but mostly it goes away if I let it sit for 2-3 minutes after grinding.

You can spray the beans with water before grinding: https://www.tastingtable.com/1402572/spritz-coffee-beans-water-before-grinding-mess-free/

I haven't tried that yet because I have a whole hopper full and trying to spray the beans at the bottom would be a PITA and the issue isn't that bad for me.

I like the idea of drilling a hole near the top of the plastic hopper and inserting a stranded copper wire into the hopper and just hooking that up to the outlet's grounded plastic cover screw. Assuming it's a properly grounded outlet. 

In reply to SV reX :

We manufacture a lot of hoses for pvc pellets, gasoline drop and vapor recovery hoses that are an issue with static.  We have a copper wire embedded inside the helix and you ground the ends to the fittings and check them via an ohm meter.  

SVreX is on target with his ideas.  

It is a properly grounded outlet.  I was fortunate when I bought this ancient house that it had already been fully rewired in 2012 with a new 200A panel.  Once I re-configured so that the grounds and neutrals had their own buses, I'm even down to less than 9V phantom.

I guess I'm really looking at GROUND COFFEE.  See what I did there?

The only time "coffee grounding" is proper grammar?

If you sit thru enough years of annual ESD training you start to remember stuff... except no, not really.  (The annual FOD training did work b/c I remember that oatmeal does not belong in a jet turbine.)

Anyway: anti-static "neutralizer" fans for electronics work by spitting out a balanced quantity of airborne positive and negative ions.
All of the charged non-conductive surfaces attract the opposite type of ion so everything ends up equally neutralized and happy.

The thing about non-conductive surfaces is that they don't conduct.
You have to touch every bit of every surface to remove the charge sitting there.

An interior ground-grounding wire might help some, but I don't think it will completely neutralize the static electric charge on every individual coffee particle.
I think fundamentally you have a slightly different problem compared to preventing a dust collector or storage tank system from turning into a massive HEI capacitor.

Unfortunately most of the DIY ionizing air purifier circuits seem to generate negative ions only.  Maybe there's a 50% chance that will help?
Link to Big Clive's page on ionizers.  Also an obligatory link to (-) ions, because Tool.

If you had airlines plumbed into your kitchen, you could get an anti-static air gun.  Sure it'll make an even bigger mess, but c'mon, it's an excuse to get an Ion Gun in the 10kV Range!!

In reply to Oapfu :

Thanks for the info. So, you just need to get a ZeroStat III gun like we used to use on our old LP records.

In reply to Oapfu :

Yeah, I suspect the real question is... are the beans giving up electrons to the grinder, or is the grinder giving up electrons to the beans?  If I knew that, I'd have a better idea of where to go.

I'm hopeful for the ground wire trick.  The nice thing about static is that it's generally pretty high voltage, so conductivity is kind of relative.  I can shock myself on a doorknob that is screwed into an old 2x4 stud in a wooden door, so hopefully it might make a difference.  This morning I tried touching the cup to the screw on the faceplate.  I think it helped a little, but it's not enough of a test to rule out the fact that it might just be more humid today.  I think it was just my brain wishing that I completed some funky science experiement.

In reply to VolvoHeretic :

This also desperately makes me want to try my powder coating gun on my coffee

I used to un-static my button down shirts with a rattle can of stuff.  I wouldn't trust it to to be "food grade" but wonder if it was sprayed on the outside of the plastic cup, would it still work?

This happens in ammo reloading, too. Powder sticks to the plastic funnel. Wipe all the plastic down with a dryer sheet. I had a box just for that purpose, but my wife used them for laundry. Weird.

Wet spoon? - https://youtu.be/T0Dh1W40ILY

914Driver said:

I used to un-static my button down shirts with a rattle can of stuff.  I wouldn't trust it to to be "food grade" but wonder if it was sprayed on the outside of the plastic cup, would it still work?

I did try static-guard which worked until I washed it off.

matthewmcl said:

This happens in ammo reloading, too. Powder sticks to the plastic funnel. Wipe all the plastic down with a dryer sheet. I had a box just for that purpose, but my wife used them for laundry. Weird.

Mmmm.  Fresh Linen coffee.  :D

Old_Town said:

Wet spoon? - https://youtu.be/T0Dh1W40ILY

 

Way too simple and not enough math for a GRM solution

(but I'll try it)