Good first star comp?

[tentacles]

I got a bunch of new goodies, and want to wet my feet with a star comp. Should I list what I've got? I have found plenty of formulas and tutorials, I just want advice on a good place to start, rather than trying to bash together some random formula that sounds nice.

 

Oxidizers:

AP

KP

KCLO4

KNO3

Sr(NO3)2

 

Metallic things:

CuO (II)

copper sulfate

TiO2

barium chloride

barium sulfate

strontium chloride

strontium sulfate

strontium carbonate

Zinc oxide

Zinc (325 mesh)

Al (8 mic)

Al (indian blackhead)

Al (sparkler)

Mg shavings

Mg sweepings (fine dust/granular)

iron oxide black

iron oxide red

 

Binders, random fuels:

hexamine

HCEcharcoal (20 mesh, airfloat)

diatomaceous earth

asphaltum

sulfur

PVC

saran

red gum

dextrin

 

I think that's about it

 

Also, with my last firefox order, I got a gallon of tepanol free... It seems it's used in making high end composite rocket stuff, anyone want it? I thought it might be useful in making stars or something (and I am unable to resist free stuff). But no way will I ever need a gallon of it!

[deadman]

If you are looking for a colored star. Try some of these. Not tested, but I'd like them to be. Hint hint.

 

Title: Blue star #2

Chem1: Ammonium perchlorate..............................60

Chem2: Sulfur............................................17

Chem3: Copper(II)oxide...................................20

Chem4: Dextrin (binder)..................................3

Chem5: Red gum or Shellac................................6

 

Title: Twinkling green star #1

Chem1: Magnesium powder (any lab grade powder)...........23

Chem2: Ammonium perchlorate..............................60

Chem3: Barium sulfate....................................17

 

Description: Magnesium reacts slowly with ammonium perchlorate producing ammonia and magnesium perchlorate, especially in the presence of moisture. Thus, the twinklers cannot be stored for more than 6 months, and they must be kept in a closed bag. During the smoulder phase, magnesium reacts with ammonium perchlorate in the dark. In the flash phase, magnesium reacts with barium sulfate, producing hot MgO and creating a green flame. The flash is followed by another cycle, since the flash rapidly consumes the reactants in the flash zone. 1) Binder solution: Dissolve 3 parts of nitrocellulose (smokeless powder or celluloid film) into 30 parts (w/v) of boiling acetone. If you're going to prepare these stars more than once, prepare more of the solution, since nitrocellulose dissolves slowly even in refluxing acetone. Approx. 30 parts of the solution (v/w) is used each time. Nitrocellulose is used as a binder, since other binders tend to interfere with the twinkling. 2) Mix the ingredients into the binder solution in the order they appear here. Proceed as usual. Note that acetone evaporates very rapidly and the stars usually dry within a few hours. I realize you didn't put it on your list but a small amount around 5% potassium dichromate would help with stabilizatino.

[Mumbles]

My general suggestion is for charcoal stars. You don't have charcoal listed, but I am hoping you can get it. There is one listed in the compostion section called "spider star". It is by far my all-time favorite. The tail is so thick and bushy. Another thread that might be worthy to go through is the Winokur Gltter thread. There are some antimony-less glitters. They have more of a silver tail with glitters mixed in, but very pretty none the less.

[hst45]

My personal favorite is tigertail, It's cheap, very easy to cut, pump or roll, and very easy to light

 

KNO3 44

charc. 44

Sulfur 6

Dextrin 6

[tentacles]

Thanks, guys! I do have charcoal, 20 mesh and airfloat (and no reason I can't go buy a 10lb bag of hardwood charcoal at walmart)

 

Deadman: i probably will give one or both of those a try, as I really want to produce a nice blue star as it's my wife's favorite color. would linseed oil be suitable for stabilizing? I had considered some potassium dichromate, but it sounds a bit unhealthy for me.

 

I can try taking a picture of the blue, when I try it, with my digital camera, but I don't have a videocam.

 

 

hst: is that airfloat charcoal, or a specific mesh?

[rocket]

IIRC linseed oil won’t protect the Mg from ammonium perchlorate, the potassium dichromate will though.

[tentacles]

Deadman: Well, I made about 35g of the blue stars a bit ago, and have them in my drier now (a dehydrator) - i took a small one of my batch of 25, and it burned nicely, i primed them with BP dust while they were still wet (possibly too wet, but i used 50/50 ethanol/water). definitely blue but i had it in a cup i shaped from aluminum foil for the test, with the leftover BP dust (.5 g maybe) I'll try making a starmine sometime soon if i can find a strong cardboard tube. I cut the stars about 5/16" cube

 

hst: i tried your recipe using airfloat, and they are in the dehydrator now too, though i'm pretty sure i got them too wet (30/70 eth/water this time) but i primed them heavily right as i cut them to help with that.

[rocket]

Buy adding the BP prime you may have a bit of trouble drying the stars or keeping them dry.

[hst45]

hst: is that airfloat charcoal, or a specific mesh?

 

Best answer is, it depends. Coarser charcoal will yield longer-lasting embers, so personally I use coffee-grinder hardwood for large stars for bigger shells, and ball milled finer hardwood charcoal for small stars for smaller shells. The beauty of this comp is that it's truly forgiving, and damned near anything you use will look good.

[tentacles]

Since I can set the temperature of my dehumidifier, what would an appropriate temperature be? What would everyone consider safe? 120F? 145F is the highest setting. It's the type with a fan, and the heating element is off to the side of the trays so any material that drops through the screens cannot fall on it and ignite.

 

I've been using 120F, but obviously 145 would dry faster and deeper.

[DeAdFX]

If you are the impatient kind I would only go to about 85F tops. I find that speed drying makes the stars way to weak and crumbley.

 

I find that a combination of room temperature and outdoors for 3 to 7 days works pretty well for star drying. This is of course assuming you use water/ethanol as the solvent and xanthan/guar gum as the binder. Other binder systems will of course vary.

 

100+F is kind of pushing it especially if you are mixing fairly sensitive chemicals. 100F+ might be acceptable for KNO3 based stars but that is a practice I think you should best avoid and even then I don't see much of an advantage of using anything above 85F.

[AcidBurn]

If you're drying stars at high temperature, only the surface will be dry, but the "core" will still be wet, because water(solvent) wont be able to vapour through the dryed layer of the stars. I think, that a little higher room temp. (about 26*C) is the best for drying stars.

[Mumbles]

Just to elaborate one something that was said earlier. You can't prime Ammonium Perchlorate stars with water and meal. The KNO3 will leach into the star and form ammonium nitrate and potassium perchlorate. Ammonium nitrate is very hydroscopic. You will have an agonizing time trying to dry them. If you insist on using BP as the prime, you have to bind it with NC lacquer. I'd suggest a potassium perchlorate based prime to make things easier.

 

As far as star drying temps, I often hear approximatly 100F for drying temperatures. I wouldn't go much higher than that. I figure this is about as hot as the hottest day in summer, so the stars should be alright. I don't force dry my stars, so it's whatever temp it happens to be outside that day that does the drying. The difference in drying speed between 100F and 145F won't actually be all that great. It's the dryness of the air from the dehumidifier that does most of the work. Heat does of course help by allowing more water into the air.

[tentacles]

Thanks guys! I did get some of the blue stars to light from the little 1" star gun I made from PVC conduit (conduit is less brittle than pressure pipe). The tiger tail stars lit beautifully and burned very long! I used about 1G of 8-17 mesh BP to propel it, nice "choof" sound and good lift - maybe 40 ft and I had put in 8 stars. It was drizzling outside which probably didn't help the blue stars, since I used the BP prime.

 

I thought I had heard something about kno3 and amm. perch, but I only thought to check safety info - thinking it might have been a dangerous incompatibility. I'll toss the rest of those stars in the grill next time i fire it up and make up some perch prime.

 

Mumbles: the 100F sounds familiar - I'll use that setting. I agree with the logic there also. At least none of the stars seemed to have cracked with my too-hot drying.

 

Pictures still to come - I was far too tired the other night to do more than fire off the mine twice.

[deadman]

I also believe stars work best when room temp dried and have a good air current over them. Please get some of those star pics up. Anyone else want to devote some time to the twinkling green? Eh eh?

[tentacles]

deadman: I would make the twinkling green, if I knew I could coat the Mg with linseed and be okay, but I've heard the amm perch + raw Mg is unstable and dangerous.

 

I can probably get some pictures maybe tuesday night?

[deadman]

Honestly, for the amateur you should be OK without the dichromate. I wouldn't let them sit around for more than a few months. Four at max.

As well as keeping them in an airtight container. If anyone else has cautions or reasons as why this info is wrong please post a correction.

 

So what's the verdict on pictures and/or video?

[Frozentech]

Honestly, for the amateur you should be OK without the dichromate. I wouldn't let them sit around for more than a few months. Four at max.

As well as keeping them in an airtight container. If anyone else has cautions or reasons as why this info is wrong please post a correction.

 

So what's the verdict on pictures and/or video?

Yes I have a reason. Mg or MgAl and Ammonium Perchlorate start reacting immediately and rather noticeably, with a rapid rise in temperature and a powerful ammonia smell. If enough comp is in one container, it will rise to ignition temperature and you could come to grief.

 

I learned that MgAl also reacted this way by experience when making some McClain Violet, from Tom Perigrin's IPP. I was packing comp into lance tubes and they got too hot to touch. I had to slap together an impromptu drying shed from some old siding and leave them in that. The heat dried them out fast, which stopped the reaction short of ignition.

 

According to Shimizu and others, dichromate is the only treatment which protects Mg from the ammonia reaction.

 

[edit] actually there are some exotic treatments with molybdenum compounds that are said to work also, but not used in normal pyro practice (yet).

[Mumbles]

I would not follow deadman's advice. The danger comes mainly in drying, not storage. If you can get them dry, you are relatively home free. Ammonium Perchlorate attacks magnesium metal. Dichromate is the only thing known to protect from it. Well, the only common thing at least. The reaction causes heat, which could potentially lead to self-ignition. This is less of an issue with small batches, but the star will be ruined if allowed to react.

 

Linseed oil coated Mg is still attacked somewhat. If you bound the stars with say NC lacquer or something, it may be alright though. Parlon stars bound with acetone can help to protect the Mg.

 

As far as coating the Mg with linseed oil, it's pretty simple. Mix the Mg with boiled linseed oil. About 4-5%. Stir it well and need it together until everything is coated. Spread it into a thin layer on paper or something and let it dry. This may take upwards of 3 months depending on the situation. There is a product called "Japan Drier", which is a cobalt salt solution, that speeds the process up considerably.

[tentacles]

Thanks, mumbles!

 

Still no pics, as we are experiencing a resurgence of winter here (14F + 40mph winds) that makes shooting conditions somewhat less than ideal.