Crumbly glitter stars

[MadMat]

I recently made a 100 gram batch of winokur 26 glitter stars. The formula is:

 

53 Potassium nitrate

21 Sulfur

10 Charcoal

6 Red iron oxide

6 Bright flake aluminum

5 dextrin

In an effort to "amp up" the effect I tried adding 10% T.W. titanium.

I cut these stars at 3/16". After three days and approximately 8 hours in a drying chamber, some of the stars are still crumbly (I know from experience this formula remains crumbly until completely dry). Some for the stars are nice and hard though. Size of the stars doesn't matter as I pumped three 7/16" comets out of this formula and they are all nice and hard. Has anyone ever had a batch of stars where some of them randomly have driven-in moisture? Is it possible my added titanium is causing the problem? Or the other possibility is that the mixture simply was mixed enough. I ran the mix through a 40 mesh screen three times. Hmm... I'm not sure what to think at this point

I kind of wonder if,in the future, I add titanium to anything else, if I should up the dextrin a percent or two.

Edited April 13, 2016 by MadMat

[Merlin]

I don't know why that particular batch would crumble. You had plenty dex. I can say I made the same formula as cut stars. They did not crumble but I will likely dispose of them because they burn a long time. They are 1/2 " not that size matters but I am afraid I will have fallout. I absolutely don't want any burning material reaching the ground. That's the little experience I have with W26

[MadMat]

I fixed the slow burn time with this comp. I combine the potassium nitrate, sulfur and charcoal, ball mill it for about an hour. I then add the remaining ingredients and run them through a 40 mesh screen 3 times. I've made this comp several times and have never had this kind of problem. Granted the stars take a little longer to dry then most other comps, but never anything like this. That makes me think it has something to do with the titanium.

BTW, I fired one of the hard stars out of my star gun; it looked great! the titanium did exactly what I was hoping to accomplish.

Edited April 13, 2016 by MadMat

[lloyd]

Mat,

I can't imagine that 1) the Ti could cause that problem (unless it's VERY contaminated with 'something'), or 2) that titanium would - in any way - 'enhance' a glitter. They're almost antithetical!

 

If a 3/16" glitter star doesn't dry completely in less than 24 hours, something is VERY wrong. My suspicion is not that they failed to dry, but that an adverse reaction has occurred in them, causing them to decompose.

 

Did you smell any hydrogen sulfide in the drying area?

 

Further, if glitters are not dried pretty rapidly, they can react slowly while wet, and that will eventually ruin the effect.

 

A 1/2% of finely powdered boric acid added to the formula (or the batch of wetting water) can help prevent that.

 

Lloyd

[MadMat]

Lloyd,

I don't smell any H2S. Actually, after thinking about what you said, I think you were referring to glitter comps that contain antimony trisulfide. Winokur 26 is a thermite based glitter, so I highly doubt that it would decompose while wet and release H2S.

[lloyd]

Nah... sulfur acts nearly the same, and that's not a thermite. The RIO is a catalyst, in that role.

 

Think about the proportions. I know the RIO and aluminum are 50/50 to one-another, but that's not the mechanism. Even if it WERE, the proportions of KNO3 and sulfur would still allow sulfuric decomposition reactions to occur with the aluminum.

 

Many of the Winokur formulae (even those containing only sulfur as the sulfur donor) warn of the use of more than 8% moisture. I like to use around 3%, and press, rather than cut -- in fact because of the adverse reactions that can occur. My stars, and even crossettes up to 3/4" dry in about 18 hours in a 100F drying chamber with good air circulation and moisture-removal.

 

 

Lloyd

[MadMat]

Yeah, I see what you mean. When I've made stars with this comp in the past, I've always had them dry pretty quickly. I'm not even sure if it is a moisture problem why they are crumbly. And the fact that only some of them are crumbly while others are just fine has me scratching my head.

Edited April 13, 2016 by MadMat