18 replies to this topic

[Mortartube]

I thought I'd post this here in this section as it deals with ball milling. I recently purchased some ceramic baking beads which are used for baking pastry blind, i.e holding it down when you partially cook an empty flan case.

I was going to try these as ceramic media in my mill. They are made of a hard baked beige coloured clay and are about twice the size of a baked bean each. They seemed ideal BUT.

Last night I held two of them in my hands and struck them together (like rubbing a flint and steel together) in a completely dark room. They sparked. Not huge or very luminescent sparks but there were definitely sparks in a dull red or very dull electric green/blue.

I would doubt that they would suffer such an impact in a mill but you can't be too careful. I wonder if anyone here with ceramic media wants to try the same thing, impacting their ceramic media in a pitch black room. I would be interested at the results.

On a different note try tearing some sellotape from a roll in the complete darkness. That sparks too.

[digger]

I thought I'd post this here in this section as it deals with ball milling. I recently purchased some ceramic baking beads which are used for baking pastry blind, i.e holding it down when you partially cook an empty flan case.

I was going to try these as ceramic media in my mill. They are made of a hard baked beige coloured clay and are about twice the size of a baked bean each. They seemed ideal BUT.

Last night I held two of them in my hands and struck them together (like rubbing a flint and steel together) in a completely dark room. They sparked. Not huge or very luminescent sparks but there were definitely sparks in a dull red or very dull electric green/blue.

I would doubt that they would suffer such an impact in a mill but you can't be too careful. I wonder if anyone here with ceramic media wants to try the same thing, impacting their ceramic media in a pitch black room. I would be interested at the results.

On a different note try tearing some sellotape from a roll in the complete darkness. That sparks too.

I have two types of ceramic media, both above 96% alumina which I have been using for milling for some time now. I will bang a few together tonight to see if I can reproduce your results.

[Mortartube]

Thanks Digger. You have a bang tonight and tell me how you get on. lol.

Seriously, it would be interesting to know the result. I actually found the brightest sparks were produced by pressing the media together hard and then striking it sharply, like striking a match on a matchbox.

This media is slightly rough on the surface.

I await your report 007.

I have two types of ceramic media, both above 96% alumina which I have been using for milling for some time now. I will bang a few together tonight to see if I can reproduce your results.

[portfire]

Interesting. Did you notice any chips, scratches in the beads Mortartube?

Digger, do you have any ceramic media from inoxia, as this is what I've been using for BP for 3 years. It would be interesting to see your results, maybe on video, IF they spark that is.

[Mortartube]

These beads are slightly rough and are designed for baking purposes. The sparks are so dim I don't think a video camera would get them. It has to be absolute darkness.

Striking them together like a match on a matchbox works pretty much every time if you apply some pressure.

[cooperman435]

Sounds like your describing Quartz being struck together?

Just a coincidence or could there be an explanation?

[digger]

Sounds like your describing Quartz being struck together?

Just a coincidence or could there be an explanation?

Yes it definitely sounds like a piezo effect going on. This can also happen with alumina compounds.

[cooperman435]

Thankyou Digger I was racking my brains trying to recall piezo effect!

[digger]

Well then!!

I have tried used 40mm inoxia media and no sparking was evident. These media are very smooth.

I tried some new 30mm grinding media that have a rough surface and it was very easy to get these to spark.

Finally I tried some 30mm media that have been in use for some time. It was possible to make these spark, but it was very difficult to do so.

So there we have it folks as has been stated in the past ceramic can spark.

[cooperman435]

Well I just tried with my lead media and I really cannot get it to spark! Tried with all 4 sizes too but nothing :-) lol

[digger]

Well I just tried with my lead media and I really cannot get it to spark! Tried with all 4 sizes too but nothing :-) lol

Ha di Ha

[Mortartube]

Thanks for trying that. I will have to get some from Inoxia. I agree that it may be the piezo effect. There may be a percentage of quartz in the beads that I have.

[Arthur Brown]

It's probably a matter of degree! I worked in a photo lab for years and even masking tape makes sparks if unrolled too quickly by hand but you can only see them if your eyes have fully acclimatised to the total darkness. The energy is too low to have an effect though.

[Valec]

I think the light produced by tape ist harmless. As far as I know, it is produced by so called Triboluminescence and it's cold light, like it can be produced by luminol (in that case, chemoluminescence). Triboluminescence also occurs with sugar crystals I heard; you can put sugar crystals in a coffee grinder and watch them in the dark, and sometimes you can see a bit of light output (which is what I was told - I haven't tried so far).
So, light isn't always produced by sparks and thus not always dangerous IMO.

[wjames]

erm....the light you see from sugar is in fact piezo-electic. happens when bonds are broken in a crystal....you should see a DL sized envolope spark when you tear the gluey bit off !....to worry you further, potassium sodium tartrate, which, you may or may not use in pyro, also "sparks"...pvdf does to......along with....wait for it.....YOU ( well, your bones)

as for the ceramic media......thats piezo electricity through and through......and for those of you who are sceptical....find a lighter with an electric ignition..the sparky type.....remove the "sparker" and break it with a hammer....in the bottom you'll find lots of tiny ceramic balls..if i remember right, they are known as PZT....lead zirconium titanate.

pzt is top notch stuff...its everywere...cars, mobiles, pc's....space shuttle....they even used it in nuclear blast protection..


guess who studied it at uni ?

back to valec.....

i played with some very strange crystals once, perhaps you can identify them for me.....they "glowed" under mechanical pressure, blue it think, but then if you"stirred them" they glowed another colour, and if you shook them, yet again, another colour.....ever heard of that ?

Edited by wjames, 31 August 2008 - 11:05 PM.