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RE: Better bottle caps

I don't know what the capacitance was of the lead shot caps.
(shotgun shot, NOT iron filings), as these were my brother's,
but I would imagine that it would not be very good. If a very
fine conductive powder were used, this could be effective
if it were tightly packed into the bottles.
I'm experimenting at the moment with this kind of thing.
I've got aluminium powder and brass and bronze powders,
purchased from a fibreglass materials store, where they are
sold for pigmenting fibreglass castings. My unsuccessful
spray was nickel....... I believe that there is an aluminium
spray that conducts, but I haven't tried that.
Another idea...... try substituting aluminium TAPE for
aluminium foil ! Can you solder aluminium tape ?
					Richard.


-----Original Message-----
From: Tesla List [mailto:tesla-at-pupman-dot-com]
Sent: Thursday, May 25, 2000 6:20 PM
To: tesla-at-pupman-dot-com
Subject: Re: Better bottle caps


Original Poster: "Michael Cox" <95moc-at-kings-school.co.uk>



What I was thinking of doing was knocking up the caps with foil outer for
toughness and a sprayed inner to get in all the cracks. They should be
quite a bit lighter than the salt solution ones and easier to move around,
you don't have to worry about spillages :) Also the idea of etching the
inside with hot conc. NaOH sounds fun to get a good surface. I might
experiment and see how they measure up agains the straight salt
soulution/foil types.

Bye the way rick, did you compare the capacitance for your solid, iron
fillings against, salt caps? Were they any better?


Cheers

mike






At 17:34 24/05/00 -0600, you wrote:
>Original Poster: "Richard Barton" <richardbarton-at-caving5.freeserve.co.uk>
>
>Hi Michael.
>                    I take it you mean the Nickel aerosol spray cans
(pretty
>expensive).
>I've tried it. The conductivity is "so so".
>I sprayed a beer bottle/salt water cap and it came out at .53 nf.
>Using aluminium foil instead, I got .65 nf. There are a couple of other
>downsides
>to the stuff too.
>a. The coating doesn't stick too well to glass. It tends to fall off in
>large flakes.
>b. It's quite delicate and if you are intending to place the bottle in a
>foil-lined box,
>the coating quickly rubs away around the edge of the bottom of the bottle.
>c. The nozzles on the cans are VERY prone to clogging up (You get a spare
>nozzle
>with the can, so they know about this problem), and even shaking the can
for
>the
>full specified two minutes, they STILL clog up very quickly and have to be
>cleared
>with a needle.
>I've gone back to foil myself.
>							Richard Barton
>Original Poster: "Michael Cox" <95moc-at-kings-school.co.uk>
>
>I came across a metallic spray in a catalogue ( I don't have the catalogue
>here, so no specs at the moment) and thought it might be the perfect thing
>to replace salt water in bottle caps. Just spray it into the bottles stick
>you electrode into the top and away you go. Has anyone else come across
>this stuff before, how good a conductor is it? I'm guessing its better than
>salt solution. Has anyone got any comments on this,
>
>
>cheers,
>
>Mike
>
>
>
>