7 replies to this topic

[Yugen-biki]

I am searching for a composition that will not make visible glow or sparks in the air. I?m planning to make round stars that starts dark and changes in to a collor. Shimizu have some comps in his book "Art, Science and Technique" and DB has wrote a page in "Best of AFN 2". DB made the best comp from reading Shimizu and not using realgar (potassium rerchlorate:80 S:20 C:1). But he says: "This produces less light than a smilas composition with red gum or shellac but still far too much white light to be considered as a workable dark composition". He also states the risk of dark comps blowing out in the air when fired in a shell.
Have enyone got a a dark comp?

[adamw]

Here is a Shimizu one:

Potassium Nitrate 75

Charcoal Airfloat 8

Potassium Perchlorate 7

Antimony Trisulfide, Chinese needle 3

Red Gum 2


It doesnt contain Realgar but SB2S3, which although isnt as nasty can still be quite hard to get.

[Yugen-biki]

Thanks for the formla!
Have you tried this one?
I have 400g of Sb2S3, grayish powder.

[Yugen-biki]

I have tested...

Shimizu changeing relay:
KNO3 35
KClO4 35
C 24
Dextrin 6

Using less dextrin (4%) and replacet is with coal. The mixture burns fast and white-ish with allmost no sparks. Testing a star made of only dark flew away!

...Is this how the dark comp is supposed to bahave or does it need more fuel?

[adamw]

When you said 'flew away' do you mean 'self propelled'?

[Yugen-biki]

I made a pill box star and when lit flew some 30-50cm on the ground. I have to slow it down I guess. I?m not looking "swimning" stars. For dark spolettes it?s great.
To day I?m going to put some time in slowing it down and keep the flame to a minimum. Maby I?ll try to get the flame smaller. I?ll post the result in the future.

[Mortartube]

If you think about it, this sounds like a great darkfire composition as most of the energy is being converted to gas and not light!

[Yugen-biki]

Yes! I have not thought about that. I have made some modifications and it?s drying now to be tested soon. A pre. test made to day is promesing. Less oxidation agent and more fuel is the trick. But not to much fuel though.