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Re: Static Gap Stains



Tesla List wrote:
> 
> >From tesla-at-america-dot-comThu Oct 17 21:27:01 1996
> Date: Thu, 17 Oct 96 07:59 EDT
> From: Bob Schumann <tesla-at-america-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Static Gap Stains
> 
> Hello all,
> 
>         I built the cylindrical static gap (Richard Quick type)
> and have a question if anybody else has seen this happen to
> their gap. I followed Richard's instructions almost to a tee
> but I could never bring myself to permanently glue the copper
> electrodes in place. I have access to a polishing wheel that
> puts a mirror shine on them. When it is time to clean the gap,
> I remove all the electrodes and polish them. I have to go
> through the re-gap and alignment routine each time but I just
> can't get myself to touch sandpaper to them. Anyway...with
> the electrodes out, I notice vertical brown stains on the green
> SDR35 PVC innerwall between where every electrode (gap)was.
> 
> Even though I have not scrubbed at the PVC because the stains
> are harmless, they will not merely wipe off.
> I am just curious what does this. Is it the x-rays or UV from
> the spark possisbly that affects the PVC? Such as the PVC
> gets a 'sunburn'? Of course this is of no operating consequence
> as the gap works as well as ever, I just wondered what did it.
> 
> Comment welcomed!
> Thanks
> Bob Schumann


Bob, 

The brown stains are most likely from UV light altering the pigment of 
the PVC.  I would also consider heat alteration of the plastic and or 
vapor deposition of copper.  I think the UV is the real answer though.

Richard Hull, TCBOR