11 replies to this topic

[Vic]

I was reading this firework formula for golden rain dating from pre 1920

1 lb saltpetre
4 oz meal powder
4 oz sulphur
1 oz brass dust
2 1/4 oz sawdust
6 dr glass dust

It calls for glass dust in the formula, can anybody tell me the part it plays?

[dr thrust]

im guessing red sparks?, id like to see it in action.
lots of weird and wonderful stuff in early pyro how successfull it was, we can only guess unless we knock a bit up and test it
kentish has a gerb formula that calls for 1 part "porcelain grains"
ive also seen bp based "blasting powder" formula with horse dung , powerful stuff apparently

[Deano 1]

Be careful who you ask advice on golden rain, you may need a shower

[dr thrust]

i remember seeing other formula containing glass dust here , and on page 194 its got to be a spark generator , similar to iron fillings ?

[Vic]

im guessing red sparks?, id like to see it in action.lots of weird and wonderful stuff in early pyro how successfull it was, we can only guess unless we knock a bit up and test it kentish has a gerb formula that calls for 1 part "porcelain grains"ive also seen bp based "blasting powder" formula with horse dung , powerful stuff apparently

I'm sure you are right Chris, but interestingly in the same book there is a portfire formula that also calls for glass dust.

3 ½ lb saltpetre
2 ½ lb sulphur
1 lb meal powder
½ lb antimony
4 oz glass dust
1 oz brass dust

[dr thrust]

erm,thinking about it perhaps yellow, not red sparks i was thinking about heating the end of a glass tube in a flame , but look at the color of the flame glass blowing
its yellow, then i remembered something in the back of my mind " sodium glass"
one of the components of glass production is sodium carbonate!
so maybe a moisture proof sodium source for your comps

Edited by dr thrust, 04 April 2011 - 07:25 PM.

[Mumbles]

Do you guys think it could just be something to agglomerate sparks? There is some brief mention in Glitter by Oglesby, and Pyrotechnica II about coarse material extending the glitter tail potentially by providing places to agglomerate the melt, IE it forms bigger drops. Something like this would make me think of a real golden rain.

Most standard BP type compositions cannot burn hot enough to melt glass, and even if it did what would happen? Nothing in it can burn, it's all fully oxidized. Nothing else is strong enough to really use it as an oxidizer either.

[crystal palace fireworks]

I was reading this firework formula for golden rain dating from pre 1920

1 lb saltpetre
4 oz meal powder
4 oz sulphur
1 oz brass dust
2 1/4 oz sawdust
6 dr glass dust

It calls for glass dust in the formula, can anybody tell me the part it plays?

Vic,

Here`s a reply I got from a few lab chemists/experts at the `British Society of Scientific Glass Blowing` that may help with your question on glass dust.

I quote;

Hi Keith

As I am not an authority on the subject I have had a discussion with some of my learned friends and here are some of our ideas:



The glass dust, probably soda glass, would give off a bright orange colour when heated at a high temperature. That would be my guess anyway!!

That and reflection would be my thought as well ,though it could help with the reaction.


You know what they say, get two glassblowers together and they'll give
you 4 different opinions...

I actually think the glass dust is used as a sort of spacer for the
ignitable materials. The sulphur would give nice blue sparkles while the
glass powder would allow gasses to build up inside the shell to make it go



Hmmm dangerous stuff glass dust as we all know.

Familiar with pixie dust, similar effects? ..



Pixie Dust Luster is finely ground mica. Mica is a glassy mineral that shimmers and sparkles as it changes direction in the light, especially when it is ground to a fine powder. Mica is found naturally in various colors, such as shades of Gold, Silver and Copper. Pigments are often added to change the color. Some of these pigments hold up in the heat, or at least provide a shimmer of that color. For example, the violet Mica is a very dark violet in its cold form, but only leaves behind a shimmer of violet when heated. This shimmer looks very much like the iridescence of a Mother-of-Pearl shell. Really neat. The greens are also dark in the cold powder but leave an iridescent shimmer of green on your bead after it is heated. So does the blue, orange and other colors. The copper, gold and silver remain true to their color when heated and applied to glass.



Mica is a mineral that is mined and used in various industries. Sometimes it is actually used as a replacement to glass, they use mica sheets in greenhouses instead of glass as it has unique heat resistant properties. Without being an amateur scientist Mica is for all intents and purposes a fire retardant material.



Glass has different melting points depending on what the composition of the glass actually is. Standard soda lime glass (the most common kind of glass) melts at something on the order of 1500 °C, or about 2700 °F, while top drawer silicon oxide has a glass melting point of in excess of 2300 °C, or some 4200 °F.

I hope some of this information proves useful.



Regards

Terri

[Vic]

Thank you all for your replies.

So no visible sparks, maybe just a glow of light from the glass if it gets hot enough and that is probably doubtful, so it has to be as Mumbles has said to agglomerate the melt.
I would think there could be a problem with blocked chokes if choked, which leads on to why the saw dust delay why not just tame the mix instead?
I would do some experimental work but I have no time before the AGM but if anybody else would like to try and who has some experience working with the like, please try.

[dr thrust]

reading up on glass, borosilicate glass has the lowest melting point 800 deg c
its main use is in lab glass , reagent bottles and the like
so if you were a budding back in the day pyrotechnician/ chemist and you were after a bit of glass dust, broken lab glass may be easily on hand?
just a theory...
would the glass dust not burn up if it was finely divided enough?
ill always remember first watching in disbelieve a pile of finely divided pyro aluminium burning lit just by a match, and yet we cook with ali pans every day

Edited by dr thrust, 05 April 2011 - 10:06 PM.

[Mumbles]

I was thinking about pure silica when I mentioned BP couldn't burn hot enough to melt glass. It certainly should be able to melt borosilicate. Borosilicate glass, being a "hard" glass, should definitely have a melting point higher than soda lime glass (being "soft"). One of the above numbers isn't right, and I'd lean toward the value of 1500C for soda-lime. A quick, un-confirmed, reference has a number closer to 650C. In fact, quite a few of the given values in crystal palace fireworks post seem to be quite off. Pure silicon dioxide has a melting point in the vicinity of 1700-1800C.

Except perhaps for pure silicon dioxide crystals, the rest of the melting points are quite approximate. Glasses being amorphous solids, or pseudosolids depending on how you look at it, have very ill-defined melting points. Most values are approximations of their softening temperatures or where they begin to act more like traditional but very viscous liquids.

Given this info, it very well could melt, but it still can't burn as it is completely and totally oxidized. Aluminum is a far different case being able to burn very easily by combining with oxygen. I'd still put my money on an agglomeration aid, whether or not it ends up molten.

It shouldn't be hard to figure out. I'd think a few tests with a somewhat granular glass powder, and some with extremely fine powder like fumed silica or something, should be able to tell if it just acting as a nucleation site or is actually melting or contributing to some degree. I guess you could use coarse and fine alumina (MP 2000C) or even zirconia (MP 2700C) or zircopax (zirconium silicate, MP 2550C).

[MDH]

It doesn't specify what alloy the brass is.

Various forms of glass have been used in thermite before (with aluminum and sulfur) and it seems to me like it may cause a delayed themite reaction in the air allowing small twinkles of gold light to appear.

This composition really isn't useful without specifics, much like a glitter...