Re: Colored sparks

From: 	Wes A Brzozowski[SMTP:wesb-at-blue.spectra-dot-net]
Sent: 	Saturday, December 13, 1997 6:37 AM
To: 	Tesla List
Subject: 	Re: Colored sparks

On Thu, 11 Dec 1997, Tesla List wrote:

> From: 	Gary Lau  10-Dec-1997 1244[SMTP:lau-at-hdecad.ENET.dec-dot-com]
> Sent: 	Wednesday, December 10, 1997 10:51 AM
> To: 	tesla-at-pupman-dot-com
> Subject: 	Colored sparks
> Last night I placed a small wad of paper towel, soaked in water, and
> thickly covered with table salt on my torroid such that this would
> constitute a breakout point.  The streamer that originated from this
> point was beautiful - BRIGHT sodium-yellow for about the first foot of
> arc, then fading to the usual blue-violet.  Try it!
> I'm anxious to try salts of other metals - copper, barium, and  strontium
> come to mind.  Two things though.  As the arc vaporized the salt, it was
> re-deposited on the surface of the torroid, so that even after removing
> the salty wad, sparks leaving the torroid were somewhat yellow (perhaps a
> concern for purists, may also be corrosive to the aluminum tape).  Also,
> while NaCl vapors and dust are harmless, other salts may not be.

I beleive it was Transtrom, back in the '20's or '30's who actually got a
patent on this technique. What he used were chlorides of the salts.
Nowdays, people in the pyrotechnic field are aware that it's chlorine
in the vaporized material that actually helps produce the reds, greens, 
and blues from strontium, barium and copper. (Monochloride free radicals
have the useful molecular spectra that produce the desired color). Sodium
doesn't require chlorine, because it's sodium atoms that have the yellow
spectra, but since sodium chloride is so cheap and plentiful, that's what
will likely get used, anyway.

In any case, chlorides of these metals will likely get you the best
results. Have fun, & let us know how it works out...

Wes B.

* wesb-at-spectra-dot-net *       "It's a magical world, Hobbes ol' buddy...       *
*                  *          ..Let's go exploring."     - Calvin           *