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Re: Rubber toroids [ graphite ]




From: 	Harri Suomalainen[SMTP:haba-at-cc.hut.fi]
Sent: 	Saturday, October 25, 1997 8:45 AM
To: 	Tesla List
Subject: 	Re: Rubber toroids [ graphite ]

On Fri, 24 Oct 1997, Tesla List wrote:
> The problems of this method stretch beyond mere dependability. It's fine
> as a classroom demonstration in a beaker, but that's about it. Since the 
> rubbed graphite isn't actually attatched to the work peice in any way,

I have a bottle of commercial sprayable graphite. It contains some sort
of binder (not specified), colloidic graphite and the solvent making
it thinner.

The manufacturer tells it has good adhesion to glas, plastics and other
even surfaces. It is primarily used for repairing cathode ray tubes
(tv's, monitors). Manufacturer also mentions "excellent solution for
galvanotechnics".

>From the experience I can tell the graphite is as *very* fine powder.
The amount of binder seems pretty low. There is just enough binder
to make adhesion good. Main component is definately graphite. Hope
this tiny bit of info helps all the people not buying the commercial
stuff.

> Also, since the graphite isn't attatched to the work peice, neither will 
> the layer of plate that you build up. Expect it to chip off readily. If

Good point. However, in surfaces like a ball it is good enough to have
a surface with full conductive (metal) layer. If it has no cracs and
covers completely the surface it cannot fall off. However, I'd presume
it is easy to damage.

I just descovered one good point in using copper chlorides: if you make
a lot of PCBs you'll get lots of copper chloride for free. You're able
to recycle the copper dissolved from from PCBs. I actually did that some
years ago when I just happened to have no other copper salt around :)

I think I've also seen copper plating with *no* copper solution when
the copper came actually from the copper electrodes dissolving slowly.
Great if you have pieces of copper to be distroyed I guess. :)
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