73 replies to this topic

[cplmac]

I think a lot of the "BP Observations" don't translate to flash. Granulation for one isn't really done with flash, rice hulls would only serve as filler (not necessarily a bad thing, saves comp), you don't really need any expansion room with flash definitely less than a third, a thicker shell would increase the heat and contribute to washing out the color, and on your last point I completely agree reports in the air are almost always superior. I also agree with you on the Mag, not on the oxidation though. I have a red flash comp that is very overfueled and looks great.

Strontium Nitrate.........30
Strontium Carbonate.....20
Magnesium 250 mesh...35
Parlon........................15

red flash pot, balanced towards color over report

I just folded the comp in some kraft paper and squibbed it.

[Creepin_pyro]

From REC.PYRO:

mikes2653

"On the blue report - colored flashes CAN be done, though most of them
I've seen are red, green, or yellow. Yellow is the easiest, and lately
I've seen some reds and greens that have been much improved. Blue
flash is a more difficult proposition than the other colors for the
same reason that blue stars using metallic fuels are problematic. High
illuminance washes out blue color, while Mg or Al are prone to
unwanted reactions with many copper compounds.

A friend of mine got a "bluish" report by modifying the old dark
report composition (potassium chlorate/antimony sulphide/sulphur). He
simply substituted copper sulphide for the antimony sulphide. I
suspect this could be improved a little by adding a few per cent of a
high-Cl content chlorine donor like HCB or Saran. Needless to say such
a mixture is quite sensitive and is neither suited for the unskilled
experimenter nor for use on an industrial scale."

[MDH]

Yeah. No shit a little sensitive...

Even then how does one go about obtaining copper sulphides? Sigma Aldricth, a specialty canadian company who distributes chemicals, is starting at $180 a kilogram for a highly purified product.

[BigBang]

What magnesium are you using?
Mesh, shape...

Ive been using 170mesh flake, and 200mesh spherical Mg, but the results have been dissapointing with both.

I have just started tests using 250mesh Magnalium, and the results are, surprisingly, a lot more positve.

This mix gives a much better red than with Mg, but the report is not as loud, but still loud enough!

SrNO3 60
MgAl 35
Parlon 5

[BrightStar]

I have just started tests using 250mesh Magnalium, and the results are, surprisingly, a lot more positve.

Interesting the magnalium is working for you... I have in my notes something labeled as 'Red Flash - working':

Sr(NO3)2 55%
MgAl (fine flake) 35%
Potassium Perc 10%

This is loud with a reasonably good colour but Karlfoxman tested it in a previous thread and believes it wasn't much better than his standard 50/50+5.

Re the chlorine donor, I think that PVC powder might be less flame retardant than parlon and adds some fuel value as well. Worth a try.

[BigBang]

Ive always used parlon in colour comps, but it does seem to slow down the speed of reaction quite a lot. The difference between adding 5% and 10% is quite dramatic. I will get hold of some PVC and give it a go. Hopefully it will work better. Thanks for that tip.

[MDH]

Bump!

No thanks to Mr. Tease-Me-much Mumbles, I've found a number of coloured whistle compositions which could alternately be used as coloured flash or report compositions.

The composition involves creating benzoates from weak bases (carbonates).

I believe another member here may know about it as he was involved in an experiment much like this at the science forums.

Barium Perchlorate, 65
Barium Benzoate, 30
PVC, 5

Potassium Perchlorate, 60
Copper Benzoate, 30
Copper Oxide, 5
PVC, 5

And so on.

Just waiting for that orange or aqua whistle. Mmm.

[BigBang]

I was recently given these formulas, havent tried them yet, (except for the yellow, which works well), but i have it from good authority that these are tried and tested formulas! They are biased slightly more towards speed of reaction than colour, so make good salutes.

#Be very careful if you try these, because of the chlorate/sulphur mix. They are old formulas, but apparently work well


Green

Potassium Perchlorate 6
Barium Nitrate 3
Flake Aluminium or v. fine Magnalium 5

Another Green #

Barium Nitrate 7
Potassium chlorate 3
Sulphur 2

Red

Potassium perchlorate 6
Strontium Nitrate 3
Flake Aluminium or v. fine Magnalium 5

Another Red #

Potassium chlorate 2
Strontium nitrate 5
Sulphur 2

Yellow/Orange

Sodium Chlorate 3
Flake Aluminium or v. fine Magnalium 2

[MDH]

I made the #1 green. It doesn't look green inside a salute casing although it's plenty bright. I think I will try adding some of my home made chlorine fuel of mystery and see how it works.

My generally recommendation overall is that we stick to magnesium and almost always include chlorine. If extreme colours aren't possible, washed out ones would also be fine in deliberation to what colour we are trying to convey (Peach I have made with calcium sulfate, magnesium and strontium nitrate with a tad of PVC donor. It took a small amount of 5/3/2 nitrate flash to ignite however. The flame was orange and the light was just a touch pink-reddish).

On another note I made blue flash but it's definitely pure white inside a salute casing.

[BigBang]

I also tried the first green and i got the same results. Unconfined it was OK, but in an aerial salute, only a faint green, that you'd barely notice.

I altered the formula to

Pot. Perchlorate 2
Barium Nitrate 4
Magnalium (10micron) 3
Parlon 0.5

This was slightly better, not as loud, but more colour, but still fairly faint.

I will have a play with the others, and see if i can tweak them to the best balance of colour/loudness.

I would have prefered to use Mg, but the finest i have is approx 50micron. The Magnalium i have is more reactive cos its much finer, so i used it instead.

[pyrotrev]

Yeah. No shit a little sensitive...

Even then how does one go about obtaining copper sulphides? Sigma Aldricth, a specialty canadian company who distributes chemicals, is starting at $180 a kilogram for a highly purified product.

Make it! - dead easy if you can get some fine copper powder.

[MDH]

Try Barium Nitrate, Barium Carbonate, Magnesium and a chlorine donor if you have access to all of these. I think generally speaking the less "clutter" we use that distorts the colouring compounds, the more colour we will have. So cut perchlorate, etc.

[ultrabuf]

Try Barium Nitrate, Barium Carbonate, Magnesium and a chlorine donor if you have access to all of these.

I have all those, what ratios do you think would work well? Like maybe
4 BaNO3
2 BaCO3
1 Mg
.5 PVC
I have no idea what ratios would be good I'm just throwing some numbers out there.

[Bonny]

I have all those, what ratios do you think would work well? Like maybe
4 BaNO3
2 BaCO3
1 Mg
.5 PVC
I have no idea what ratios would be good I'm just throwing some numbers out there.

You could try looking up some flash formulas on the pfp database and then maybe working from there.

[MDH]

Magnesium and carbonates alone actually deflagerate very quickly so I think you're fine, although you may want to up the magnesium content a little bit.