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Subj:.COLORED FLASH,

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Date: 02 Mar 1994 10:15:32 -0500 (EST)
Subject: COLORED FLASH,
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Subj:.Colored flash, for pyro.dis

A few bits on "colored flash" from the files of the New Hampshire Pyrotechnics
Association.  Briefly, it seems to be more trouble than it's worth, unless there
is more development...
regards
dwp



Some thoughts on Colored Flash
"Light the Twelve"

After reading the November 1992 NHPA Newsletter article on Colored Flash, I'd
like to add my 'penny cracker's worth", and shed some colored light on the
subject. 
.["Light the Twelve is a shell buiilder of some note, PGII Competition
.shooter and prize winner.  Attendees at Convention have seen his work.
        In short: when he talks, listen up....]

I have had some experience in using colored flash, and would like to share some
vital information that was not in the original article.  As was stated in the
Reminder: " Flash is probably the most hazardous of all pyro compounds".(1)
Well, folks, colored flash is likely more hazardous.  As with any mixture
utilizing magnesium powders, there are particular dangers that must be dealt
with. 

First of all, the magnesium that must be used for the flash to be effective is
the granular type, of at least 100 mesh.  Atomized magnesium will produce a
handsome illumination star, but isn't reactive enough to give the flash effect.

Thus, the more reactive magnesium is more dangerous to handle. All magnesium
powders must be protected in some manner from the corrosive attacks of the
oxidizers they are in contact with.  According to Takeo Shimizu's article in
Pyrotechnica VIII, linseed oil would be most effective in protecting magnesium
from all the oxidizers used in published formulas. 

But, alas, coating magnesium with linseed oil slows the burning speed of the
composition to the point of being useless as a flash powder.  The next best
coating is potassium dichromate, which is only slightly attacked by the
oxidizers.  Although potassium dichromate is an extremely nasty chemical to
work with, it must be used in this application.  Instructions for treating the
magnesium can be found in Dr Shimizu's article(2). 

In magnesium star manufacture, which is more common, linseed oil coating and
atomized magnesium powder work quite well with all oxidizers except ammonium
perchlorate., used in strobe stars. As an added advantage, most mag stars
contain a relatively large amount of Parlon (chlorinated rubber) and are bound
with acetone, which dissolves the rubber and provides an almost waterproof
covering for the magnesium. 

In flash formulas there is no such protection from moisture.  This presents a
very real concern, especially with the red and purple formulas, which contain
strontium nitrate.  The hygroscopicity (tendency to absorb water vapor) of this
compound is quite high, leading to problems in areas of high humidity.  I can't
think of anything much worse than a large salute full of damp magnesium and
storing oxidizer, except, maybe, storing that device in MY magazine. 

I would advise anyone contemplating the use of colored flash to limit it to
small salutes, such as lambetti, thunder, cannonades, etc.  Actually the effect
seems much better in these small devices, as the smoke produced by the burst
reflects the light and enhances the color.  I would not advise using formulas
containing Strontium Nitrate in humid climates, or anywhere that moisture could
be introduced inadvertently.

It would be best not to store any device containing colored flash for any
length of time.  The colors produced by the flash formulas are not very strong.
Without some standard of reference, they may actually appear white.  All in
all, in my opinion, the effect is not worth the effort or danger. 

1) See also AFN no 124, January, 1992, What 
About Flash, by Bill Ofca.
2) Pyrotechnica VIII, Studies on Strobe Light 
Compositions, by Dr Takeo Shimizu.

Trivia Time
A few items, from Modern Chemical Magic, Lippy & Palmer.  "Modern" is a bit
misleading...  My guess is mid '50s... 

Colored Flash Powder:

Red
"powdered" magnesium  2 parts by weight
Strontium Nitrate    2 parts by weight

Green
"powdered" magnesium   2 parts by weight
Potassium Nitrate          2 parts by weight
Powdered Boric Acid          2 parts by weight
Powdered Sulphur          2 parts by weight

Haven't tested these, no idea of the "gotchas".  Not having seen details of
colored Flash elsewhere, might be a field for research, including the best way
to get "flash" as opposed to "bang". 

Ellern, Millitary and Civilian Pyrotechnics, alludes to a company in California
selling several different colors of Flash, but gives no formulas. 
A Flash from The WiZ

A note came in from The WiZ (Which wiz? The ONLY WiZ, the WiZ from the PGII.)
Some interesting ideas about flash, and its employment, originating with some
material from Westech. 

This month some compositions, then some novel applications.  Still looking for
notes on "flash without bang", which seems to be a matter of construction. 

Reminder... Flash is probably the most hazardous of all pyro compounds.  Know
what you are doing, or get help.  DO NOT ball mill mixtures.  DO NOT mill
mixtures in any way.  The ONLY known method of making flash type mixes with any
safety is small batches, by the diaper method.  The Blue employs Paris Green,
one of the more toxic compounds. 

RED:
    Magnesium powder     1
    Strontium Nitrate    1

GREEN:
    Magnesium powder    10
    Barium Nitrate      10
    PVC                  1    

YELLOW
    Magnesium powder      1
    Sodium Oxalate        1
    Potassium Perchlorate 1
    
VIOLET
    Magnesium powder       10
    Potassium Perchlorate  10
    Cupric Oxide            3
    Strontium Nitrate       3
    PVC                     1    

BLUE
    Magnesium powder        20
    Potassium Perchlorate   20    
    Paris Green (!!)         6
    PVC               1    

The magnesium should be 100 mesh, or finer. 

The color is most apparent, it seems in the light from the flash, as it falls
on other things, than in the material itself, being somewhat washed out by the
brilliance of the flash.  Any confinement leads to an explosion. 
