Problem with Orange star comp...

[braddsn]

Hey fellas...I have rolled 2 batches of the following orange stars, 1.5kg each, 9mm stars rolled on peppercorns, and NOT primed yet. Both batches dried for a week with a fan on them, then once they seemed dry I threw them in a 600 watt dehydrator for 4 hours. I can crush them between my fingers. I have to squeeze but not super hard.. they just crush into powder. All of my other stars are impossible to crush with my fingers. I am using dex out of the same container as all of my other stars. At first I thought maybe I forgot the dex, but I am very methodical when I mix comps, and although I may forget dex once, no way I would forget it twice, so I am ruling that out. Here is the comp: It is Jopetes forumla - KCLO4 - 48, Strontium Carbonate - 12, Sodium Oxalate - 5, Redgum - 11, Parlon - 10, MgAl - 11, Dex - 4. In the comp notes, it says you can use either Cryolite or Sodium Oxalate. I used the Oxalate, but I also have Cryolite on hand. Thanks for any pointers. Also to note, I rolled 3 other color star batches on the same day I rolled these, and all 3 batches dried rock hard. It's a mystery. It must be a chemical issue or something.

Edited March 24, 2015 by braddsn

[psyco_1322]

4% is just on the light side, I have a purple that's like that, I use 6% in it to get hard stars.

[braddsn]

psyco that's worth pondering... thanks for the idea. I guess I could bump up the dex and try it with a small batch!

[MrB]

What happens if you wet the crushed stars enough to be sure the dextrin all got properly activated, and then dry them out again? If memory serves me right, dextrin wont reactivate, so if you get any stickyness when dried, you didn't get it all activated in the first go.

And if i remember wrong, it's still a valid test, if they get harder, then you still didn't get it wet enough the first time, and if it's just the same, you were good, and the solution is more binder, or using a different wetting agent, to use redgum / parlon as the binder instead. Perhaps not quite as fun to roll stars using aceton - parlon for binding...

 

Good luck.

B!

[JOPETES]

Hello Braddsn. I have always dried my stars outdoor air slowly and never had any problems with the orange made with sodium oxalate, in fact I know professionals and formulas that are almost identical to mine PDF with more or less the same proportions sodium oxalate and dextrin. I think a possible problem is that too fast drying may crack the stars and lose dureza.Other cause may be that the stars are not shot long enough and this is very important because when it is formed round star there to be shot for a time sufficient for the mixture to be compressed and also depends on the amount of water that you are using in star formation, while excess water is detrimental. it is also important the ratio of water and alcohol, I always used about 65% water and 35% alcohol. If you use too much alcohol and little water is not readily soluble dextrin and not doing a good adhesive mission.

Cryolite is slightly better in the sense that it is less hygroscopic, that is, almost not absorb moisture.

[braddsn]

Thanks for the replies guys. I have rolled 20 different batches of stars this month and I do everything the same with all of them. All of my current stars are Jopetes formulas and they are great. I use 25 alcohol 75 water and let them air dry for at least a week on a screen with a fan blowing on them. All of my other stars dried rock solid. 2 times I have rolled these stars and they dry, but easily crumble. I will try the next batch with cryolite and see if it helps.

[Mumbles]

Have you used all of the chemicals in this formula in other batches of stars successfully? This is really just to make sure. Strontium carbonate can be kind of fluffy, and I could see it making the composition difficult to consolidate. I generally make cut stars, so they're usually a bit easier to ensure everything consolidates and all that. I've also never had trouble with 4% dextrin, but again with cut stars, everything gets significantly wetter.

 

The other thing to maybe worry about is a reaction between the sodium oxalate and the MgAl. An overly basic batch of oxalate (or cryolite for that matter), could potentially react with the metal. In this case, unlike when nitrate or sulfur is around, no indicative odors would be noticed. The by-product is sodium hydroxide, which is notoriously hygroscopic. Have you noticed them heating up at all? Using boric acid could help to buffer everything.

 

This is not just star bias You might want to try to make a batch of cut stars. It'd tell you if it's just a consolidation problem, and you'd probably also notice the composition heating up some, since your hands are in there. They'll make fine mines or cylinder shells. Okay, maybe that last part was star bias.

[braddsn]

Mumbles I was hoping you would weigh in on the chemistry aspect of this. One thing that confuses me, some folks will say when rolling stars, it's important not to over wet the comp. Other folks swear by toro, which is a slurry and is VERY wet to say the least. Then some folks say it needs to have enough moisture to activate the dex. I am not really sure what advice to follow as far as that goes. However, the reason I am stumped and posted this problem is because I am consistent with everything I do, thus I am using the same chemicals making these stars as I am all of my others. Same dextrin, same amount of water when rolling. I rolled a batch of red the same day (strontium carbonate red) and they dried rock hard. The first batch of this orange that I rolled, I primed them at the same time.. just like I do all of my stars. When they were air drying I noticed most of them were developing cracks and were easily crushable when dry. So, I tried this second batch without priming them... thinking maybe this particular comp needed to dry first before being primed. They look fine, no cracking or anything, but when I squeeze em, they just crumble, and they seem dry all the way through. I could try cutting them. I will first mix a small batch with cryolite instead of Sodium Oxalate and see what happens. The only thing I can figure is that it has to be a chemical thing, and the only major difference in this comp and all of my others is that this one contains the oxalate. Weird. One of the great mysteries of life! By the way you mentioned cylinder shells... what is a cylinder shell?

[bajadudes]

OK my 1st post but I have been doing this for a little over 25 years. I would not use the fan. On some compositions a fan will quick dry the outer layer and actually trap moisture inside. Also as a note when rolling, if the comp is being over wet with your spray while rolling you usually get bumpy/lumpy weird alien looking stars. Just something to watch for. I like to use a 50/50 mix of Isopropyl and water and usually between 4-6% dex.

 

Hey, what's wrong with Italian paper cylindrical/canister shells?

Edited March 25, 2015 by bajadudes

[braddsn]

Bajadudes, that's all I need is another guy in the cylinder shell camp!!! LOL.. j/k. The fan has never presented a problem before... I have it on low, and since the stars don't get any time in the sun, it helps a little...albeit not much, it's just a box fan. My stars are perfectly round when I am done with em so maybe that's a good sign. 4-6% dex is the range for all of my stars. Like I said, the mystery is that this batch has turned out bad twice, and if you knew how many stars I roll (about 8kg per week lately) , and they all come out great, it would baffle you too! haha... I am banging my head against the wall. I am gonna give them another go this weekend, using cryolite instead of Sodium Oxalate and just see if that's the issue. I tried to roll 2 batches of Tangerine last fall, and both batches turned out bad... and the sodium oxalate I used in them is the same sodium oxalate that I am using now. Could it be possible that there is something wrong with my Oxalate? I know it's unlikely.. but something is definitely amiss. I will post my results here when I try again, and hopefully the solution.

[Wiley]

Pssst, Brad, get some hemp twine and end disks and make a nice salami. You know you want to!

[braddsn]

Wiley! Shut it! I know in the future I will break down and make some cyls. The spiking intimidates me.

[BengalFlair]

Dear braddsn,

I am so curious with the mystery and I would like to add some points.

Shimizu stated somewhere (most probably in FAST) sodium oxalate greatly decreases the viscosity as well as the cohesive power of SGRS which might be true somewhat in case of dextrin also I think (although I don’t have any authentic data or experience in case of dextrin as well.) Some increase of dextrin or replacing it with other suitable binder might help IMHO.

I would request you to watch the burning characteristic of a pile of well dried crumbled powder of stars.

It would not burn well (might create some slag and deviation of colour) as like the fresh composition I think, if sodium oxalate already reacted with mgal as mumbles stated.

Edited March 25, 2015 by BengalFlair

[braddsn]

BengalFlair, thanks for the advice. I am going to try the composition with Cryolite next. The stars I believe are fully dry. They burn quick and completely with great color and no slag. They are just easily crushed.

[Mumbles]

Have you ever made a composition successfully with the sodium oxalate? It sounds like this may be your problem. Tangerine also contains metals. One idea might be to try a sodium oxalate based glitter. I'm partial to Lancaster Yellow personally. With the sulfur and nitrate around, you might notice more easily if it's causing a reaction with the metals.

[coogan1997]

I know this probably has nothing to do with your question brad, but i was wondering how many stars do you roll in one batch and how long does it take. I'm asking because I'm still trying to decide wether roll or pump and which would be quicker

[braddsn]

I believe the Sodium Oxalate must have been the problem. I rolled another batch a couple days ago of the orange, and used Cryolite instead, and they are already rock hard. All of the other chems I used were the same, and from the same batches. Same amount of water used rolling, same amount of dex. Only explanation is the Sodium Oxalate.

[JOPETES]

Hello Braddsn. If you have problems with sodium oxalate does not matter, use of cryolite is better as it provides slightly better color and is not hygroscopic. As I said in a previous post, I have not had any problems with oxalate and some fireworks factories are using more or less the same formula for the orange. It may be a matter of the quality or size of the particle oxalate, the finer the powder is better.

For yellow lemon and lime green cryolite use.

luck with your stars.

 

[braddsn]

Thanks Jopetes. The colors on your chart are fantastic! I rolled the pearl white tonight and it is great. I am going to pump some comets with this comp for shell rising effect. I also rolled some of the blue with hexamine.