Slow gold question

[braddsn]

Hey fellas, I fired a shell a couple nights ago with slow gold stars. At least half of the stars were broken up/pulverized when the shell broke. Regular MCRH, no booster, 4" shell I then pulled out my box of slow gold stars and checked them, and they are pretty easy to crush between my fingers. I am trying to figure out if I forgot the dextrin or not. Should they crush between my fingers like that? My other stars (colors, D-1, etc) will not crush between my fingers no matter how hard I squeeze, they are super hard. Are slow gold stars perhaps soft because of charcoal content or something? Just want some input before I throw these stars out. Thanks!

[Arthur]

Are you sure that they are really dry? If so I'd consider crumbling them and adding some dextrin and re forming them. Could be hard because the Ti flake will destroy mill jar or media and some of the charcoal is meant to be coarse. I use a disposible medical syringe for slow gold -saves cutting up a nice tool.

[braddsn]

I rolled them on peppercorn cores. They are very dry. Thinking i may have forgotten dex.

[TYRONEEZEKIEL]

Too much dextrin may slow the comp down. If you can screen it through a 40 mesh and it all passes just fine, I'd say you forgot dextrin. How long have they been drying?

[enanthate]

They might have become driven in, the outside is dry and won't let the moisture in the core out. Ive never experienced this myself, but i think they would crumble easily.

One way to be certain is to crush a few stars, weigh them and let dry, weigh again after a few hours.

 

You didnt make new dextrin before this batch?

 

Arthur, do not mill Ti. The media would be the least of your concerns in that case.

[Livingston]

Just make sum star mines with them!! I would agree with your gut! you forgot the DEX!!!

[braddsn]

They are dry for sure. I rolled em about 3 months ago. But I just got a chance to load em in a shell. I am just wondering how easily they can be crushed between two fingers. Obviously, colored stars are impossible to crush.. they are hard as rocks. But being that this is a high charcoal content star, I thought maybe it would be easier to crush. Livingston, thanks for the idea, that is exactly what I am gonna do with em!

[GalFisk]

I haven't made slow gold myself, but my very charcoal-y TT stars with 5% (or is it 7%) dextrin are uncrushable.

[Mumbles]

The slow gold stars should be uncrushable as well. I'd go with forgotted/shorted dextrin, or it was somehow poorly activated.

[skid68]

Did you roll them with some water? If you rolled with alcohol only, the dextrin will not activate.

Edited January 16, 2015 by skid68

[Arthur]

Basically crush and rebuild them

[enanthate]

They are dry for sure. I rolled em about 3 months ago. But I just got a chance to load em in a shell. I am just wondering how easily they can be crushed between two fingers. Obviously, colored stars are impossible to crush.. they are hard as rocks. But being that this is a high charcoal content star, I thought maybe it would be easier to crush. Livingston, thanks for the idea, that is exactly what I am gonna do with em!

"Driven in" means the outside is dry while inside is wet. Doesnt matter if they have been drying for a year.

 

It is most likely that you forgot the dex tho :>

It only happens once!

[GalFisk]

As for how a star can become driven in, it happens when the outside dries so quickly and thoroughly that it creates an impermeable shell around the moisture/solvent still inside.

[braddsn]

Ok guys looks like from what you all are saying I forgot the dex. All of my other stars are un-crushable (with my hands). Good to know that slow gold is no exception. I will load em in starmines and make some new ones! Thanks!

[AdmiralDonSnider]

One other possible explanation is that you were using another batch of dextrin than you were in case of your color stars. In particular I am thinking of white dextrin instead of yellow one. I had very bad results using the former, white variety, stars were easily crushed by hand. Back then I learned that white dextrin requires plenty of water to be activated properly, much more than is used in star rolling. It is better suited to sparkler production.

[braddsn]

I discovered the problem.... I decided to take a closer look at the stars. I have 4 tupperware containers for each color of star that I have, (1 container for each size). The first container I picked up, I noticed moisture on the inside of the lid. Needless to say, you guys were right. Not dry. I dumped the whole batch into my dehydrator, and in 2 hours they were dry and hard as rocks. Lesson learned. I actually rolled that batch some time ago, before I had my dehydrator. Now that I have the dehydrator, my method in drying is much better. I let em air dry on a screen with a fan for 24 hours, then put them in the dehydrator for 3 or 4 hours. This method gets them dry for me every time.

[enanthate]

Haha, youre better off deleting that last post mate ;p

 

I know that you are "sure" this time, but really, have you checked the weight of 10 or 20 stars when drying that way? 24 + 4 hours sounds little to me, depending on the size obviously.

Let them sit for another 24 hours and check the weight again, just to be sure. Not that its crucial, but some stars perform better when really DRY.

My 16mm pumped takes 5 days to dry completely, in a warm and dry room.

[FlaMtnBkr]

I was going to post about double checking they were dry but didn't because it sounded like you had it figured out. But one way to check is to put them in a zip lock bag with some air in it and set in the sun for a while. If there is still some water it will show up as condensation on the bag.

 

Some bigger stars can take weeks to dry if they are dried naturally and take a lot longer than you would think. Another way to check is to cut one in half and make a scratch all the way across. It should behave the same and leave a dusty scratch across the star. You can also weigh them until they stop losing weight each day but if they get driven in some they may not lose much and seem dry when they aren't. So it's best to double check with any method.

[psypuls]

I have 200g of slow gold running in my ballmill right now, I wanted to try something different so I interchanged potassium nitrate with sodium nitrate.

I hope that there will be no trouble awaiting me doing this. I expect longer drying time that's all.

[pyrojig]

I hope your slow gold is just the base comp ( without metal) being milled. Milling with metal is a dangerous thing, and could lead to an explosion even in a bp based comp. I only mill BP ( or bp based charcoal comps) in a mill. Never color or metal laced comps.

[psypuls]

of course, thanks anyway

[pyrojig]

Awesome, just never know the experience of some folks on here . Some comps do benefit from milling , but usually it is minimal or very short milling of the base comp. .I find that most charcoal stars can be screen mixed with very good results . ( usually the chems are milled separately beforehand ) . I find that milling increases burn speed too much in most comps, and reduces the charcoal tail to a short one. I do however like the faster charcoal star comps for mixes with lots of Ti or FETI , for use in spider shells .

[MondoMage]

I have 200g of slow gold running in my ballmill right now, I wanted to try something different so I interchanged potassium nitrate with sodium nitrate.

I hope that there will be no trouble awaiting me doing this. I expect longer drying time that's all.

As I understand it sodium nitrate is hygroscopic. So it's entirely possible that your stars may never fully dry.

[GalFisk]

Sodium nitrate has a critical relative humidity of 72.4%. If you can keep your %rH below that (using heat, dehumidification or both) they should dry fine.

To compare, calcium chloride (used as a deliquescent dessicant) has a crH of just 22%.

[psypuls]

So Might I be able to put them in the oven for a day or two? on 100C