Interesting that among a bunch of formulas for colored stars in
Weingart calling for KClO3, there's a pink box star compo calling for
KClO4.  It's shellac fueled, uses plaster of Paris to impart color,
and is dampened with alcohol.  Since it's specifically a box star
compo among a bunch of recipes for cut (or unspecified form) stars, it
would be expected to be difficult to ignite and dampened with just
sufficient alcohol to allow the light pressing typical of box stars,
with their thin, lance-like casing.  However, I did succeed with it in
round stars with plenty of hot silicon-containing primer coat, and it
did give a nice shell break.

What I wondered was whether, like other shellac-fueled compos, it
could benefit from KClO3 as the oxidizer, specifically for ease of
ignition; or whether the CaSO4, like other sulfates, required the
hotter fire of perchlorate to impart color.  Might some compromise
chlorate-perchlorate mixture be suitable?

I'm also wondering whether I could get it to tail with Al flitters
without killing the pink in the head.  And yes, I know I can get pink
with a mixture of conventional red & white compos, or an over-fueled
Al red.

Robert

Interesting that among a bunch of formulas for colored stars in
Weingart calling for KClO3, there's a pink box star compo calling for
KClO4.  It's shellac fueled, uses plaster of Paris to impart color,
and is dampened with alcohol.  Since it's specifically a box star
compo among a bunch of recipes for cut (or unspecified form) stars, it
would be expected to be difficult to ignite and dampened with just
sufficient alcohol to allow the light pressing typical of box stars,
with their thin, lance-like casing.  However, I did succeed with it in
round stars with plenty of hot silicon-containing primer coat, and it
did give a nice shell break.

What I wondered was whether, like other shellac-fueled compos, it
could benefit from KClO3 as the oxidizer, specifically for ease of
ignition; or whether the CaSO4, like other sulfates, required the
hotter fire of perchlorate to impart color.  Might some compromise
chlorate-perchlorate mixture be suitable?

I'm also wondering whether I could get it to tail with Al flitters
without killing the pink in the head.  And yes, I know I can get pink
with a mixture of conventional red & white compos, or an over-fueled
Al red.

Robert

Amongst the various pieces of misinformation I've seen about the
hazards of chlorates is the assertion that the chlorate/sulphur hazard
extends to mixtures of chlorates and sulphates. This is not generally
the case, because the sulphur in sulphates is already completely
oxidized. It is true that copper sulphate should not be mixed with
potassium chlorate, because it is water-soluble and the solution has a
decidedly acidic pH.  However, calcium, strontium, and barium
sulphates are stable neutral salts, and pose no hazard when mixed with
chlorate.

On p. 19 of the 1947 edition of Weingart, that author states: "The
tendency of potassium chlorate to explode is very strong in the
presence of sulfur, sulfides, and sulfates which sometimes release
minute quantities of sulfuric acid." I think the reason for Weingart's
specification of perchlorate in the pink box star you mention is that
he erroneously believed that it would be hazardous to use chlorate
with calcium sulphate.

On Oct 12, 3:54 pm, John Reilly <strb... at (no spam) sbcglobal.net> wrote:

I haven't tried the Weingart composition you spoke of but in general,
shellac alone as a fuel doesn't burn as well with potassium/ammonium
perchlorate as it does with potassium chlorate.

That's why I raised the issue.

One thing is certain, it will smoke a lot!

They do.  Maybe an illuminated smoke trail will have to do instead of
a spark tail!  Actually the time I used the Weingart formula, it was
in color changing stars where the other layer was a "granite", so it
was smoking all the way, including the Si-containing layer of primer.

Robert