Tutorial on static electricity in grinders - Page 5

Grinders are one of the keys to exceptional espresso. Discuss them here.
flyguyjake
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#41: Post by flyguyjake »

Thanks so much for that tip!

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FotonDrv
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#42: Post by FotonDrv »

Barry Bayer: Thanks for those static facts!
That Light at the End of the Tunnel is actually a train

Netphilosopher
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#43: Post by Netphilosopher »

bdbayer wrote:Well, I have to weigh in on this topic. I usually stay out of these debates because people with their own experiences will always contradict the facts of static electricity.

My "opinions" are based on 17 yrs of working all day every day in the field of static control. so here are some facts based on my knowledge of the science:

The glass funnel is an insulator, it will hold a charge whether grounded or not.

Plastic bins are the same as the glass funnel, insulators and can not be grounded.

Touching a burr will not ground it unless you are connected to ground yourself. It may create a small sudden discharge but the charge will rebuild.

Wearing no shoes does not ground you unless you are standing on a grounded surface.

Charged coffee grounds will attract to anything that is metal whether grounded or not because a charged surface (the coffee) will look for a ground reference or an oppositely charged surface.

I have done tests with my AC ionizing equipment and this is the best way to kill the charge. This equipment creates a field of positive and negatively charged ions that will neutralize anything in the field. These products are what I sell but they are way too expensive for a home coffee setup.

Here is a test for you folks to try. It's called passive ionization. Take something multipronged, like a fork or one of those tined things you hold turkey slices with, and ground (to earth ground) all the tines. Hold that about 1/4" from the coffee grounds. When a static field is felt by the sharp grounded points (the sharper the better) it excites a flow to and from ground naturally generating a small passive ionized field. As the coffee grounds pass in front of the sharp grounded point it should become reduce the charge. You could do this by hold a fork in one hand (just above the coffee grounds path) and touch the sink with the other.

The problem with this theory is that it takes about a 5kV charge to excite that flow. If your charge is lower it may not work. I could measure the charge on some coffee from my Maestro but the field will be read from the bin and the coffee grounds. I have no static problem on my Mazzer.

Just some thoughts based on the facts of working with static in industrial applications, try it and see if it works for coffee.

Barry Bayer
Thanks.

Would an aluminum comb work? Or a steel flea comb?

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civ
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#44: Post by civ »

Hello:

First of all, thanks for your input.
Static is one of our natural enemies here at HB. =-)
Buttercup wrote: Charged coffee grounds will attract to anything that is metal whether grounded or not ...
This has been exactly my experience, no matter how much I tried to get the grinder 'grounded'.

Long time ago, when I was an enthusiastic audiophile and vinyl records were static fiends, I purchased an anti-static 'gun' which greatly helped in reducing surface static helping do away with 'most' of the dust that clinged to them.

I think it was called "Zerostat" or something like that and it was fairly expensive. When used, it gave off a particular 'ozone like' odor. (needed to get it close to your nose to actually smell it)

I once had a hand held piezoelectric gas range lighter which seemed to work more or less the same way, except that instead of shooting ions, it made sparks when you squeezed the handle.

When trying to find a solution to the static problem in my Cimbali Max, I went looking for something that would do something similar to the Zerostat and came across this:
Ion Generator

Buttercup wrote: This equipment creates a field of positive and negatively charged ions that will neutralize anything in the field.
I have not tried it yet (need to find a 220v model) but from what I understand, it won't work as it only generates negative ions. Am I correct?

Once again, thanks for your input.

Cheers,

CIV

Edit:
Found the Zerostat ...

Question answered.
Zerostat
Seems that it generates both positive 'and' negative ions.

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bdbayer
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#45: Post by bdbayer »

Would an aluminum comb work? Or a steel flea comb?
Yes, that would probably work. I measured my grounds this morning and only saw about 300 volts. I think Baratza is using a static dissipative material on their bin though. If this is all the voltage we are dealing with my suggestion will not work.
When trying to find a solution to the static problem in my Cimbali Max, I went looking for something that would do something similar to the Zerostat and came across this:
That looks like a small high voltage ionizer and it is exactly what would do the job. The Zerostat is a manual version of this technology. It generates positive ions on the pull and negative on the release (or visa versa, I don't remember). Just use it with fast trigger pulls and be sure to keep it aimed at the target both pulling and releasing. Too slow and only one direction will result in added charges.

Barry Bayer

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civ
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#46: Post by civ »

Hello:
bdbayer wrote: That looks like a small high voltage ionizer and it is exactly what would do the job.
That would be great.
But the web page says it generates negative ions, says nothing about generating positive ones.

---
"Compact negative Ion Generator cleans air impurities and provides a fountain of fresh air. These negative ions are the same type that are produced in a thunderstorm."
---
bdbayer wrote: The Zerostat is a manual version of this technology. It generates positive ions on the pull and negative on the release (or visa versa, I don't remember).
The page says:
---
"How it Works
... when the trigger is squeezed, positive ions are generated and when the trigger is relaxed, negative ions flow."
---

Unfortunately a Zerostat runs about US$135, has to be used quite close to the object (like inside the doser) and is a 'throw away' item once it stops working. =-/

I wonder if just as there are 'negative' ion generators like tone I posted earlier, there are 'positive' ion generators. One could then use one of each in tandem which would then (theoretically) produce equal amounts of each type of ion.

Does that idea hold any water?

Thanks for your input.

Cheers,

CIV

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bdbayer
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#47: Post by bdbayer »

I wonder if just as there are 'negative' ion generators like tone I posted earlier, there are 'positive' ion generators. One could then use one of each in tandem which would then (theoretically) produce equal amounts of each type of ion.
I have never seen a small positive ion generator, air purification is usually done with negative, but that is out of my area. The way AC type ionizers work is that the ions are generated by boosting line voltage to several thousand volts. The positive ions are generated on the top side of the sine wave and negative on the bottom. Oxygen molecule are charged by the corona discharge coming from those sharp pins. IF you only have one polarity you are adding charge.

If the unit you have pictured only generates negative it is probably just hooked to one side of the AC circuit. I I wonder if the same device would generate positive if hooked to the opposite side of the AC line. Might be something to ask an electrician. This device just looks like it boosts the voltage. the drawback is that it looks to be what we call "hot" in that the pins are not resistor limited or capacitively coupled. You would get quite a shock if you touched one of the pins.

That Zerostat has really gone up since my days with viny, but with what we spend on machines???

Barry Bayer

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Peppersass
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#48: Post by Peppersass »

It appears that the problem is the lower funnel. Has anyone tried simply removing it and grinding directly into a paper cup sitting on a riser? I thought I had seen a photo of that, but looked back through all the HG One threads and couldn't find one. I did find a photo of grinding directly into a Melita filter with the lower funnel removed. Obviously, you have to get the container close enough to the bottom of the burrs so that coffee doesn't spray all over the place.

It also occurs to me that it might be possible to coat the inside of the funnel with a non-toxic substance like the stuff they use to seal marble kitchen counter tops. Would that just act like the glass insulator, or would it block the grounds from being attracted to the metal?

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Terranova
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#49: Post by Terranova »

Peppersass wrote: It also occurs to me that it might be possible to coat the inside of the funnel with a non-toxic substance like the stuff they use to seal marble kitchen counter tops. Would that just act like the glass insulator, or would it block the grounds from being attracted to the metal?
From various coatings which I have tried (25 or so), I took the most promising one which is a mix of PTFE (something like Teflon) and ceramics which is applied at a temperature of more than 400°C.
It has an anti grip / slide and easy clean effect.
My grinder is laying there in parts, but very soon I can tell if it has an effect on statics.
The golden funnels are Titannitid (TiN) coated on the outside and also the burr mount got the ceramic stuff (underneath).
Transition is under the O ring. (the O ring is semiconducting)


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JohnB.
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#50: Post by JohnB. »

I've removed the stock HG-One funnel & grind into a plastic AreoPress funnel sitting in a paper cup. If I mist the beans lightly before grinding I have no static issues. If I don't use the RDT mist the grounds build up on the bottom of the burr carrier, come up around the lower edges of the carrier mount & can be a pain to brush off. Any grounds clinging to the plastic funnel sides fall down into the cup as soon as the funnel is moved.
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