4 replies to this topic

[bigtonyicu]

Hi everyone,

I was doing some reading and someone was talking of separating the layers with of colour in a colour changing star with something called "Dark Fire" he didn't give the composition all he said is it's a high binder & Charcoal, low sulfur & KNO3 black powder. it's a very slow burning composition around 2 sec/mm.

So I've tried to make something that would meet those criteria and I'm not having much luck
KNO3 52%
C 43%
S 5%
Dextrin +9%

it gives me something that burst at about the right speed but it's still producing lots of light and spark

does anyone have a better formula,

that mix if good for hot star but seam to wash out the beginning of cold star so blue looses lots of it's beautify

Edited by bigtonyicu, 16 July 2008 - 04:46 PM.

[digger]

Hi everyone,

I was doing some reading and someone was talking of separating the layers with of colour in a colour changing star with something called "Dark Fire" he didn't give the composition all he said is it's a high binder & Charcoal, low sulfur & KNO3 black powder. it's a very slow burning composition around 2 sec/mm.

So I've tried to make something that would meet those criteria and I'm not having much luck
KNO3 52%
C 43%
S 5%
Dextrin +9%

it gives me something that burst at about the right speed but it's still producing lots of light and spark

does anyone have a better formula,

that mix if good for hot star but seam to wash out the beginning of cold star so blue looses lots of it's beautify

I assume that you are talking about a dark relay compound. 2 seconds per mm sounds a little on the slow side. There are compounds listed in Shimizu's book The Art, Science, and Technique. If no-one else pipes in with the formula I will list one later (by the way they are KP based from memory)

[digger]

Try this Shimizu dark comp

Potassium Nitrate 75
Charcoal Airfloat 8
Potassium Perchlorate 7
Antimony Trisulfide, Chinese needle 3
Red Gum 2
I assume it can be bound with SGRS or Dextrin at 4% - 5%

[bigtonyicu]

Try this Shimizu dark comp

Potassium Nitrate 75
Charcoal Airfloat 8
Potassium Perchlorate 7
Antimony Trisulfide, Chinese needle 3
Red Gum 2
I assume it can be bound with SGRS or Dextrin at 4% - 5%

thanks, I'll give that a shot, should be rolling some stars in the next week or so

[Bonny]

Here's another one you could try:

Changing Relay #2
Source: Shimizu[1], page 187
Comments: This type of composition is put between two color layers in a star to create the illusion that all the stars change their color clearly and simultaneously in spite of slight deviations in manufacture.
Preparation:

Potassium perchlorate.............................81
Red gum...........................................13
Soluble glutinous rice starch.....................6


On another note, I've been rolling up a batch of tigertail to blue (Shimizu B-70) and the change seems quite fast as the TT burns off so quickly. I used a 50/50 mix to change over. I have only tested on the ground, but I should be building a shell soon.