The Blues: Part 3
In the endless pursuit for the very best blue firework star color available, we consumed a large quantity of time and firework chemicals. I have seen what I perceived to be very good blue color firework stars. But trying to make them is not easy. I will share the results with you. After hearing a great deal about Paris Green as a blue firework chemical colorant, we decided to test this opinion.
Japanese for the Color Blue
#1 Light blue firework star, medium burn speed and slight residue.
#2 Was Weingart's pg. 132, same as #1.
#3 Would not light; think the stearin is too high.
#4 Very nice blue firework star, fast burn, no residue.
#5 Nice blue firework star that’s red at flame edge, with light carbon residue.
#6 Very nice turquoise firework star with medium speed parlon residue.
#7 Red flame no good, heavy carbon residue.
#8 Same as above.
#9 Nice blue firework star, medium speed and light residue, parlon?
#10 Very nice blue firework star, clean burning.
# 11 Very good blue firework star, medium speed, clean burning.
Note: #6 burned too hot and went into green but it could be cooled down with lactose.
Keep in mind if you choose to use these firework chemicals for your firework stars; work in small quantities; start with 10 gram batches; always wear a respirator and gloves; keep all tools clean; and never add finely divided aluminum to chlorate. Copper Acetoarsenite (Paris Green) was used in [all?] of the tests. It does contain Arsenic. Also you must see two blue firework stars together to judge the best color. Side by side, there is no better blue firework chemical than Paris Green in my opinion.
Doc Barr's Blue RocketDoc posted a message to the PML concerning a good blue sky rocket pyrotechnic formula:
Doc's quoted source: Craig Villenueva
PYROESOTERICA"Rhapsody in Blue"
Observations of Some Published Blue Pyrotechnic Formulas
Producing a viable blue firework star with good depth of color has always been challenging for the firework builder and many pyrotechnic formulas have been published over the years. To compare the relative effectiveness of some of these recipes (as well as a few unpublished ones), 16 different, 500-gram samples were worked up and tested at FPAG shoots. Data from these experiments along with subjective comments and source information follow herein, but the reader is asked to bear in mind that the focus was on producing firework stars for aerial artillery shell use only and consequently some of the mixtures regarded here as failures might still find useful application in other firework articles.
|Black copper oxide||15|
From R. Veline in J. Baechle's "Pyrocolor Harmony." Good ignition, a whitish, "washed out" blue characteristic of most metal fuel blues. A Useable pyrotechnic formula, but it’s clearly inferior in saturation to other pyrotechnic formulas.
"Morning Glory Blue", from R. Pimentel in J. Finckbone s "Green Notes", Vol. 1, Issue #3
Good ignition, another Perchlorate-based firework star composition with better color than B1 that’s probably cheaper also. Useable.
A "sugar" blue firework star containing potassium chlorate, copper oxychloride, and lactose, plus some small amounts of chlorine-donor, resin fuel, and dextrin. This proprietary pyrotechnic formula was given to the author with the request that it remain unpublished so exact component percentages cannot be listed here. Readers can nevertheless glean enough information from the description for design evaluation.
Good ignition. A chlorate composition using the classic low-temperature carbohydrate fuel system. Superior in color saturation to both B1 and B2 and one of the three-best tested non-ammonium perchlorate firework star compositions.
"Cyan Blue" From J. Baechle's "Pyrocolor Harmony". Poor ignition. Color saturation was mediocre at best. This is a substandard pyrotechnic formula.
From A. Anzalone and modified by J. Finckbone in "Green Notes" Vol. 1, Issue #2. Good ignition. This is a chlorate-based firework star composition. Taking advantage of HCB's higher fuel value and superior flame deoxidizing capacity. Color saturation was as good as B3...perhaps slightly better. One of three-best tested non-ammonium perchlorate firework star compositions. Substitution of the now difficult-to-obtain HCB is possible but should be carefully done in order to avoid adversely affecting ignition and burn rate.
A chlorate-based blue firework star containing black copper oxide, Parlon, red gum, and dextrin. This is another proprietary pyrotechnic formula "on loan" to the author that must remain unpublished. Good ignition. Somewhat brighter than the other non-metal blue firework stars. Color saturation was acceptable, but inferior to either B3 or B5.
A blue candle firework star modified by J. Baechle in the old "American Pyrotechnist" publication, originally from Lancaster. Good ignition. This chlorate composition equaled or surpassed both B3 and B5 in color saturation and may have been the best non-ammonium perchlorate firework star pyrotechnic formula tested. Again, HCB can possibly be substituted for with a watchful eye toward ignition and burn rate.
Another "sugar" blue firework star, this one comes from Dave Mayotte in PGI bulletin #47. Good ignition, color saturation from this chlorate/carbonate/carbohydrate mix was almost identical to B1 although it contained no metal fuels. This is an inferior color pyrotechnic formula.
|Black copper oxide||13.4|
T. Shimizus B48 from Pyrotechnica #6. (With dextrin substituted for rice starch.) Good ignition. A perchlorate firework star composition with a long burn time in relation to other blues tested. Color saturation was inferior and deemed unacceptable.
This formula is from "Chemistry of the Elements" and reprinted in D. Haarmann's "Pyrotechnic Formulary" and the Aug. 1993 1st Fire. Good ignition. This potassium-perchlorate augmented ammonium perchlorate firework star composition was in the minority of tested ammonium perchlorate pyrotechnic formulas in regards to ignition. Color saturation was very good and burn rate was acceptable. This is a good pyrotechnic formula.
"Winokur Blue" from R. Winokur in APFN pg. 506 and reprinted in D. Haarmann's "Pyrotechnic Formulary." Poor ignition. This ammonium perchlorate-only/hexamine firework star composition was unique among tested ammonium perchlorate pyrotechnic formulas in that its color saturation was poor. Bad ignition and bad color make this firework star composition fairly useless.
H. Ellern's "Ashless Blue" #79 reprinted in Haarmann's "Pyrotechnic Formulary" and modified by the author by substituting chlorowax for paraffin and adding dextrin. Good ignition and burn rate. This ammonium perchlorate-only firework star composition was also the only pyrotechnic formula tested using elemental copper. Color saturation was good.
This formula is from J. Baechle's "Pyrocolor Harmony" pg. 31. Poor ignition. This ammonium perchlorate-potassium perchlorate combination yielded good color saturation and OK burn rate, but its inability to take fire with standard priming techniques makes it an unacceptable firework star choice.
From D. Bleser's "Round Stars and Shells." Poor ignition. Again, a formula with good color and OK burn rate that was unable to take fire from normal priming. This is an impractical pyrotechnic formula.
This formula is from S. Majdali in the Aug. 1993 1st Fire. Poor ignition. This complicated firework star mix generated ammonia gas upon dampening but did not heat up. Burn rate was OK and color saturation was very good but as with most other ammonium perchlorate pyrotechnic formulas its inability to take fire from ordinary priming renders it impractical.
D. Bleser's blue from AFN #64, Jan. 1987 modified with dextrin binder. Good ignition. A simple, but effective, firework star composition employing a single entity fuel/color donor. Color saturation was very good, as was burn rate. One of only three useable ammonium perchlorate firework star compositions tested, its primary disadvantage may be the limited availability of copper(II) benzoate.
Since the goal of the experiment was to gain ground in the search for a better, practical blue firework star, all firework star compositions were dampened with water, cut, and tumbled in prime. No special solvents or multistage priming techniques were employed. All potassium chlorate and potassium perchlorate were formed into 1/2" cubes and primed with mealed pulverone while ammonium perchlorate firework star compositions were formed into 3/8" cubes and primed with a potassium perchlorate-based meal to avoid chemical incompatibilities with the dampened ammonium salt. Copper acetoarsenite (Paris Green) was omitted from testing due to its cost and limited availability.
When designing or selecting a blue pyrotechnic formula, careful consideration should be given to flame temperature and fuel/oxidizer primary systems. It is well known that reds, greens, and yellows benefit in both brilliance and saturation from hotter flames since SrCl(g), BaCl(g), and ionic Na (the respective spectral emitters) are stable at metal-fueled temperatures (while most of the interfering ions are not!). CuCl(g), however, is the preferred ionic blue emitter, is destroyed by such high temperatures and the flame is whitened.
Saturation is always sacrificed for brilliance and vice-versa when creating the pyrotechnic blue flame. Choosing a cooler burning fuel/oxidizer primary system will generally yield better color saturation, all other factors being equal. Below is a list of the most commonly used fuels and their relative temperature groupings:
|All carbohydrates (i.e. lactose, sucrose)|
All organic gums (i.e. red gum, rosin colophony, shellac, vinsol)
The metals (i.e. magnesium, aluminum, magnalium, titanium, antimony, antimony salts)
The primary system must not be cooled (slowed) so far that the burn rate becomes inadequate, however.
These tests also showed that hexamine, while enlarging flame size with no apparent spectral interference, clearly inhibited ignition in ammonium perchlorate firework star compositions. Of seven such pyrotechnic formulas tested, all four containing hexamine exhibited very poor ignition while the three without it ignited well. No tests using hexamine with potassium chlorate or potassium perchlorate compositions were done, but future experiments are planned.
Only distilled water was used during this experiment, as should be the case with all aqueous processing systems. This avoids potential pH problems and undesirable ionic contamination. Copper and copper salts are prone to strange reactions in the wet state, and these reactions may be accelerated in the presence of metal fuels and extreme pH. It must be remembered that copper, a component in many batteries, is multi-valent and capable of electrolytic reactions. Lancaster opined in the early 1970 s that copper salts should never be dampened in the presence of metal fuels. Experimental results and a recent accident with such a mix support this position. The author feels that metal fuels have no place in blue pyrotechnic formulas since they invariably degrade color saturation while increasing the rise of composition heat-up and premature ignition. An exception might be where thrust is desired (as in the case of go-getters) but in this situation, a waterless system of organic solvents is used. Even here, however, unpleasant reactions have occurred and caution is advised.
One possible avenue of experimentation toward improving the safety of aqueous system blue firework star compositions might be to choose copper salts with the lowest relative solubility. The author knows of no such data currently available with respect to this concept, but a partial list of solubility of the most commonly used copper salts is presented here for the reader's evaluation. Available copper expressed as molecular percentage is also included.
|Copper(I) Chloride||Very Slightly Sol.||64.18|
|Copper(II) Fluoride||Slightly Soluble||62.58|
|Copper(II) Benzoate Dihydrate||Slightly Soluble||20.78|
|Copper Sulfate Pentahydrate||Very Soluble||39.81|
The blue firework star designer is cautioned that lower solubility may make a firework star composition safer but not safe as surface electrolytic activity can occur with any copper entity in the wet state. Empirical research will surely continue in the never-ending quest for a better blue and it is hoped the experimental data and theories presented here will assist future color designers.
1. Shimizu, T. 1980. Studies on Blues and Purple Flame Compositions made with Potassium Perchlorate. Issue VI, Pyrotechnica: Occasional Papers in Pyrotechnics, Austin, Texas.
2. Baechle, J. 1989. Pyrocolor Harmony, A Designer s Guide. Jamestown, North Dakota.
3. Kosanke, K.L. 1981. The Physics, Chemistry, and Perception of Colored Flames. Issue VII, Pyrotechnica: Occasional Papers in Pyrotechnics, Austin, Texas.
- Ammonium perchlorate (CH5000)
- Barium chlorate (CH5505)
- Barium nitrate (CH5102)
- Chlorowax (CH8075)
- Copper benzoate
- Copper carbonate (CH8087)
- Copper Gluconate
- Copper oxide, Black (CH8096)
- Copper oxychloride (CH8098)
- Cupric chloride (CH8091)
- Dextrin (CH8107)
- Gum arabic (CH8131)
- HCB (hexachlorobenzene)
- Hexamine (CH8142)
- Lactose (CH8169)
- Magnalium 50/50, 200 mesh (CH2073)
- Paris green
- Parlon (CH8210)
- Potassium benzoate (CH8219)
- Potassium chlorate (CH5200)
- Potassium Perchlorate (CH5400)
- Red gum (CH8230)
- Saran (CH8248)
- Shellac (CH8255)
- Stearic Acid (CH8298)