Potassiumchlorate Posted January 4, 2013 Posted January 4, 2013 How hard can it be? I know that a few of us do it, and it was the preferred binder for centuries. Why I consider this is because I want to try AP blues, and also think that shellac should be better with AP than red gum. Red gum burns 2.0mm/s with AP and shellac burns 1.6mm/s, so it isn't considerably slower as the case is with chlorates.
pyrojig Posted January 4, 2013 Posted January 4, 2013 With shellac go in slow increments of alcohol. Let it sit for a while, it takes a while to dissolve the shellac. My last batch turned to soup. Some say it is better to dissolve the shellac first then add your comp.
Potassiumchlorate Posted January 5, 2013 Author Posted January 5, 2013 I have pulverized shellac. If I try to bind with it, I think I will add some phenolic resin to the alcohol to improve the strength. I have rolled stars with this shellac before, but it takes some patience.
pyrojig Posted January 5, 2013 Posted January 5, 2013 (edited) Wont need to. The shellac is extremely hard when dry. It makes for a good binder for comps, but does require some special care and patience . Edited January 5, 2013 by pyrojig
Mumbles Posted January 5, 2013 Posted January 5, 2013 I find it's tendency to skin over and dry slowly to make it a less desirable choice for a binder.
Bobosan Posted January 6, 2013 Posted January 6, 2013 Why not just add a bit of dextrin to the comp and bind with water? I say this thinking the shellac (fine powder) is more of a fuel source than a binder.
Potassiumchlorate Posted January 6, 2013 Author Posted January 6, 2013 I don't want water in the ammonium perchlorate.
Mumbles Posted January 6, 2013 Posted January 6, 2013 Any particular reason you're trying to avoid water and AP?
Potassiumchlorate Posted January 6, 2013 Author Posted January 6, 2013 Yes, I've read that it might "trap" the water inside the crystals. But maybe this isn't the case if the crystals are very small, like 50µm or so?
Mumbles Posted January 6, 2013 Posted January 6, 2013 That's something I've never heard before. I would think it would have come up if it were a legitimate concern given the frequency that AP compositions are bound with water.
Potassiumchlorate Posted January 6, 2013 Author Posted January 6, 2013 OK, you are the expert. I'll give it a try. If it doesn't work, I'll post here and rant about it
Potassiumchlorate Posted January 11, 2013 Author Posted January 11, 2013 But for New Blue an alcohol or acetone soluble binder should be the best. The Copper benzoate monohydrate might turn into dihydrate and/or absorb water if bound with dextrin or SGRS. Bleser himself used NC-lacquer, but I see no reason why shellac shouldn't do. The tricky thing is to get the amount of alcohol exact. I tested to use the shellac as binder for a pumped 15mm "exhibition green" star, and it seems like you must first over-wet it a bit and then dry it very thoroughly to get the full "force" out of the shellac. But they did it back in those days when their only prime was BP, so there is no reason why it souldn't work at least as good today.
pdfbq Posted January 11, 2013 Posted January 11, 2013 (edited) Yes, I've read that it might "trap" the water inside the crystals. But maybe this isn't the case if the crystals are very small, like 50µm or so?AP traps a little water when it crystallizes. I don't think it will recrystallize, make new crystals, when you wet your comp with some water. Edited January 11, 2013 by pdfbq
Potassiumchlorate Posted January 11, 2013 Author Posted January 11, 2013 The compositions I'm about to (re)test are, beside New Blue, Pihko AP#1: Ammonium perchlorate 60Copper(II)oxide 20Sulfur 17Red gum/shellac 6 This can be bound with +3 parts of SGRS without problem and a composition from a member here on the board: Ammonium perchlorate 68Copper(II)oxide 17Hexamine 15 This can not be bound with SGRS or dextrin, because the hexamine is hygroscopic and will never dry. He binds it with shellac himself.
Carbon796 Posted January 12, 2013 Posted January 12, 2013 (edited) I bind the New Blue formula with SGRS all the time, you shouldn't have a problem with it. Although the original formula specs binding with N/C I believe . You might also be confusing a chemical being hygroscopic with one that is water soluble. There is a difference. There are quite a few formulas that call for Hexamine with Dextrin as the binder. I've also used SGRS for binding formulas with Hexamine in them. They dry just as well and just as fast as any other non-hygroscopic star formulas, in my experience. - Rich Edited January 12, 2013 by Carbon796
Mumbles Posted January 12, 2013 Posted January 12, 2013 Hexamine itself is not very hygroscopic. However it has a reputation of being so. Impure hexamine is hygroscopic to some degree due to its hygroscopic impurities. The same is true of strontium nitrate. The impurities also give it the majority its reputation of having a bad odor.
Potassiumchlorate Posted January 12, 2013 Author Posted January 12, 2013 I have a bottle of hexamine from 2005. It says 99% purity on the label. It has a slight smell of "fish", though. I have tested it before and it seems that stars made with it are pretty hard to ignite and in some cases even hard to consolidate. Now I have milled it for one hour, and it looks perfectly dry. Hm
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