aapua

Hi everyone again,

just to share 2 ideas I finally tested few days ago.

The first one is about the method to get the burst charge. Instead of coating rice or whatever I used swab or some other type of soft foam plastic. Cut it into pieces of 5x5x5 mm.This time I used regular mealed BP (75/10/15) with +5% of Dextrin and +5% of DarkPyro Aluminium. I added water to get nice "soup" and put the swab into it. The foam takes pretty nicely the mixture in it and dries, making pretty hard pieces. The performance wasn't too good, though. It was too slow. Probably it's better to use perc/s/c micture with some extra Al. But this is my next experiment, I wasn't in my lab when making this, and I hadn't perc there. Anyway, this method helps to make the burst charge very easily and quickly. The disadvantage is that in bigger shells you have to use some hard neutral fillings, the foam is physically not hard enough.

The second idea is to use a very special epoxy-glue in the mixtures. The glue I got is Wessex Resin's CASCOPHEN RS 12 A with resin hardener RXS 22 A. The good point is that the stars dry within 24 hours, the mixtures with this glue are very stable, and you can prime stars before they dry. Though, because of high content of different elements it was pretty hard to get good green and blue, with red there was no problem.

For red I used:

KClO4 - 50%
Sr(NO3)2 - 25%
Hexamine - 10%
Al DarkPyro or Mg - 2%
Resin RS12A - 10%
Resin hardener RXS22A - 3%

After drying very hard, ignites easily and burns quite a long time.

Any comments are more than welcome.

Regards,

Aapua

Just a short comment / question. A fireworks symposium will be in 18-22 April, in Japan, Otsa. I just wander if somebody of this forum's people is going to go there? I hope I personaly will...

Hi there,
a question this time.
I know there are many companies in UK that sell colored sparklers. Would someone please describe them a little bit? What is interesting to me, is how good is the color (I know there are red, green and blue sparklers)?

Thank you

Hi everybody and greetings from Estonia!

First. Forget about things like "I have only KNO3 and sulphur and coal and sugar, but would somebody pleas tell me how I can make blue, green and red colors with only these chemicals?" Does not matter, you do pyrotechnical stuff for your own pleasure or for others to see, you need some special equipment and chemicals. The part of technology is a weak side to me, but I know pretty something about chemistry and pyrochemistry.

A suggestion. There are pretty many sites where you can find a huge amount of mixtures, some of them are really good, some are not. But, if you happen to find a russian site, you are lucky one. Cannot say it about all russian sites, but at least some of them have materials stolen or just got from different research labs of Russia. And these works are good.

A good site (it worked a week ago, but last few days it was down. I hope it would be fixed again) is www.pirotex.by.ru - if you happen to read russian.

Now finally about chemicals.

UROTROPINE. I would say it is the God's gift. Use it as a fuel and you see what I'm talking about. One more good thing - it helps you make mixture, that gives big flame, but burns very slowly. Only be careful - the burning of urotropine is something different. First it melts, and if you use too much of it, it kills the flame and the reaction. But, using A BIT too much gives extra golden sparks, so the effect in the sky is markable. Always would be good to use al-powder in the mixture. It helps to "carry" the burning zone. Don't be afraid - the color becomes even more bright, but remains good and clear. The wellknown fact is (although the mechanism of it is not known) that you can make good colors even with the simple stable chlorides - BaCl2, SrCl2, CuCl2. Use urotropine, the chosen cloride and magnesium powder (works pretty well with aluminium powder too). This is useful, when you don't have nitrates or something else. But, the question of oxygen source remains.
Sad thing might be that in order to get good clean colors, it would be nice to have some AMMONIA PERCHLORATE. Although potassium is very weak colorant, I say it just destroys the possible good colors. Especially bad is KClO3.
As a binder, I would suggest to use dextrin. The drying time is long, OK, but the slower the drying process, the better the results. If you have mixtures containing huge amount of aluminium powder, you may have noticed it is pretty complicated to mix it with water. It is a good way to solve the problem - use first a small amount of acetone, mix it well, let it dry a bit, and only then add water. Now your work is easier. For the mixtures with big amounts of C dust you may do the same.

Few mixtures as well.
RED.
Sr(NO3)2 - 35
NH4ClO4 - 35
Al powder - 10-15
Urotropine - 10-15
Dextrine - 5

For beautyful GREEN simply replace Sr(NO3)2 with Ba(NO3)2.

The blue color is something that amazes me. In this case, urotropine does not give so especially good results (but they are good anyway). Calomel is good, but expensive and poisonous. What you may find, is copper acetate - it works very well, CuO and Cu(NO3)2 do well, too. What I use, is something odd - Cu(NO3)2 * 3CuO. Of all tested chemicals it gives the best result. A good BLUE with simple chemicals:
NH4ClO4 - 40
CuO - 10
Cu-acetate - 10
Cu(NO3)2 - 15
Urotropine - 12
Al powder - 8
Dextrine - 5

For YELLOW I use sodium oxalate.
Just play with chemicals - use urotropine to get big flame, have 5 - 20% sodium oxalate in the mixture, choose oxygen source and that's it.

For the beautiful ORANGE take the mixture for red, and add +1%dextrine and +5-7% Na2C2O4 (sodium oxalate).

Somebody asked about PINK?
This is my way:
Sr(NO3)2 - 30-35 (32)
NH4ClO4 - 30-35 (32)
Al powder - 25-35 (30)
Dextrin - 5-10 (6)
Burn VERY bright, but a little bit too fast. I call the color BABY PINK.

SAFETY, SAFETY and once again SAFETY.
These chemicals together - urotropine, al-powder, ammoniumperchlorate and some nitrate - are reactive when moist. Just smell it - you can feel ammonia? This is what I'm talking about. Do the mixture only in small amounts and at once do the work with it till the end. The more water you use, the higher is danger.
Do an experiment - make a mixture, for example for red color, add water to get a mixture like a creamy soup and let is stay. Soon the smell of ammonia grows bigger, the mixture starts to bubble, the mixture "grows" and hardens. When you touch it, you can feel it has become hot. Wait even more and you can see self-ignition. I just want to say that when you use these chemicals, be careful and dry your ready-made stars ABSOLUTELY COMPLEATLY.

Few words about covering the stars.
There is an interesting chemical I use. K3[Fe(CN)6] or red blood salt (this is direct translation from both estonian and russian. I have no idea, how you might call it in english). Anyway, it is very common and cheap chemical.

The primer I use is:
KClO4 - 50
K3[Fe(CN)6] - 20-25
C dust - 20-25
Dextrine - 5-10

I cover the stars 3 times.
1. Take 2-3 parts of star mixture and 1 part of primer.
2. Take 1 part of star mixtur and 2 parts of primer.
3. Use only primer (I often decrease the amount of dextrine for the last covering).
The stars ignite very well and easy, the main color would be seen immediately and there is a very nice tale of golden sparks behind the flying star.

And the last but not least. I said urotropine stars give big, brigth flame and burn slowly. The star (without primer, just the main mixture) of about 5x5x5mm burns up to 7 seconds. Now make pump or cut stars, covering only one side with the primer (there are many ways to do that). For the cylindrycal 75mm b**b I use up to 300 gr of small, longlasting stars (maybe 500-1000 pcs). Can you imagine the picture in the sky?!?!