Some strange properties of SGRS

[Potassiumchlorate]

If I'm not completely incompetent and have myself to blame, I think this deserves a special thread. It isn't chemistry to be precise, since it's more of the physical properties, but it suits best in chemistry, of course.

 

Am I the only one who has experienced that SGRS doesn't work in silver stars and TT stars but very well in compositions with high oxidizer contents and organic fuels?

[Potassiumchlorate]

No-one? This is embarrassing and frustrating. I know that my SGRS is good, but it seems that I'm doing something wrong when it comes to stars with high metal or charcoal content.

 

I still have some 100 grams of dextrin of good quality and 1 kg of dextrin of a more dubious quality (a friend bought it from the same source, and he says that it is too weak; I haven't tested it yet, though), but I'd like to use SGRS instead, since it's both much stronger and protects better against water once really dry.

[FREAKYDUTCHMEN]

TT should work fine. In some comps it won't work.

[WSM]

No-one? This is embarrassing and frustrating. I know that my SGRS is good, but it seems that I'm doing something wrong when it comes to stars with high metal or charcoal content. I still have some 100 grams of dextrin of good quality and 1 kg of dextrin of a more dubious quality (a friend bought it from the same source, and he says that it is too weak; I haven't tested it yet, though), but I'd like to use SGRS instead, since it's both much stronger and protects better against water once really dry.

 

Maybe a search through Dr. Shimizu's book, "Fireworks, The Art, Science and Technique" will reveal some useful information about using SGRS in various compositions. It's worth a try, anyway, as he has written more about it than any other author I'm aware of. Let us know what you learn...

 

WSM

[Peret]

No-one? This is embarrassing and frustrating.

It's Thanksgiving Day in the USA, so any US members within shouting distance of a woman preparing the banquet were running around doing chores, then eating, then cleaning up, then probably sleeping it off. I know I was. Consequently a quiet day on APC. Now Mrs P has gone to camp out in front of her favorite store (the doors open at midnight) so I can sit at the computer without being yelled at.

 

I've used SGRS in all kinds of stars including charcoal and glitters, and they all set perfectly hard. However, you're not supposed to use alcohol in the water with SGRS - 5% doesn't seem to do any harm but 30% inhibits it.

[Potassiumchlorate]

I have less than 5% alcohol in it now.

 

Hm, I should read Shimizu more thoroughly. I have the book on a CD, and I have read about the better adhesion properties of SGRS in that very book, but maybe I have missed something anyway.

[dan999ification]

why do you want them water resistant? ive never had any problems with charcoal stars and them getting wet. once in a shell or mine you can store it in an airtight/watertight bag or tub.

i have soaked shells that i didnt fire in a bucket of water for 48 hours only to open them and find the contents completely dry and still very flammable only the time fuse was comprimised, the flashbag stopped the water getting in.

i would worry more about the finished items getting wet and the fuses not working than the stars.

is it more for the challenge?

make some dextrin it doesnt have to be difficult.

 

dan.

 

 

[Potassiumchlorate]

Once the water is out of them, I don't want it in again. Even my parlon stars have absorbed some water, though in that case I don't know if it went in when making them or afterwards.

 

Ironically my dextrin bound Electric Magenta made in 2009 are still functional, but the parlon bound ones made in 2010 were almost destroyed by moist, so I just burned them on the ground.

[Mumbles]

I've yet to encounter a mixture that SGRS would not properly bind. Is this related to the pumping thing you've been having issues with? Most of my stars are cut, so they always get plenty of water available to them.

[Algenco]

it's not uncommon for an SGRS bound comp to require 20% water, but even with all that water they dry as fast if not faster than dextrin

[Potassiumchlorate]

It's rock hard once dry, and it seems to have better fuel qualities than dextrin as well. I mixed one gram barium chlorate/SGRS 4:1 and it burned fiercefully.

 

I just don't get how much water is enough and how much is too much. I'm pumping stars now and it seems that it tends to be either too dry or too wet. With dextrin I have a better instinctive feeling when it's just enough water.

 

But I think 20% is a pretty correct number, yes.

[Potassiumchlorate]

No-one else interested? Aren't there any more people who have had trouble with using SGRS in the beginning?

 

I think I have finally gripped it now, though. I must say I haven't rolled any yet but pumped them. Theoretically I prefer rolled stars, but big ones are easier to pump, and I don't own any star screens, so I have to sort the different sizes by hand.

 

My conclusions:

 

*Never use any alcohol with SGRS

 

*Use about twice the amount of water compared to dextrin. It must have more time to "settle" too.

 

*Once "settled" the drying time is relatively short, despite the larger percentage of water used.

 

*The final stars are very hard

 

I pumped a few barium chlorate stars:

 

Barium chlorate 86

Red Gum 10

SGRS 4

 

They just need a little more drying and are then ready to be tested. With SGRS it also seems that there is no need for stearine or chlorowax to "lubricate" the star pump either.

[Potassiumchlorate]

Update: They are however still hard to roll. Is it me being so incompetent, or is SGRS so much different from dextrin?

 

What pisses me off the most is that SGRS is the superior binder once dry, but that it's hard to handle for me. It won't stick when I roll. I use pure water, but after a while the surface tension should be broken and the composition stick to the stars anyway. But it doesn't.

[Mumbles]

SGRS takes a while to fully activate. It's really better for rolling via the toro method where it's activated in a slurry as opposed to the more western spray and dust methods. I've heard of it being done, but they must have a lot of patience.

[skipflashboom]

I've read through two complete threads about Dextrin and SGRS and I still have no idea what SGRS is!!! If you are going to start a new thread please define all of your terms so that those who follow said thread can maximize their learning.

[Mumbles]

Soluble Glutinous Rice Starch. We sometimes take relatively common acronyms for granted. I agree it's good to use the full term and define acronyms at least once though to avoid confusion.

[taiwanluthiers]

there are confusions too about what they are, some think it's rice high in gluten, but it's not.

 

Glutinous rice is a special type of rice that is particularly sticky when cooked. It is used for making mochi, Zhongzhi (a chinese food item wrapped in leaves, commonly eaten during Dragon Boat Festival), and others. It is also known as "sticky rice". Don't use mochiko (which is the powder used for making mochi) because it needs to be cooked in order for it to activate, what you need is the cooked variety, which according to Shimzhu SGRS is made by cooking Glutinous rice, then grinding up the rice which gets you a very sticky mass, then it is dried and ground to obtain SGRS. I got mines from a food supplier who calls it "cooked glutinous rice powder", while I am still not sure if it's "SGRS" it binds fairly well. It's a lot cheaper than Dextrin too (at least for me)

 

I actually prefer dextrin when making cut or pumped stars... because SGRS gets very sticky when it's wet... not good when you're trying to keep stars from sticking to itself. However I still haven't mastered wetting cut star patties right because I think most the time I am getting them too wet.

Edited February 1, 2013 by taiwanluthiers