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Making hygroscopic chemicals none-hygroscopic?


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#1 pyrotechnist

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Posted 06 April 2010 - 11:27 PM

Anyone know how to make any chemical especially sugar none-hygroscopic? I thought about using wax or NC lacquer to coat the grains in a protective layer but not sure. One reason I want to do this is because I want my R-Candy to actually stay dry for once. Some of you may think, why not use a different chemical but then I aint sure what other chemical can achieve the same results as sugar but without absorbing so much water. Another one I want to damp proof is sodium nitrate.
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#2 digger

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Posted 06 April 2010 - 11:37 PM

Anyone know how to make any chemical especially sugar none-hygroscopic? I thought about using wax or NC lacquer to coat the grains in a protective layer but not sure. One reason I want to do this is because I want my R-Candy to actually stay dry for once. Some of you may think, why not use a different chemical but then I aint sure what other chemical can achieve the same results as sugar but without absorbing so much water. Another one I want to damp proof is sodium nitrate.


Good luck with that.

I know not much help. Pretty much the only way dealing with it is to seal the the items in a bag until they are used. Other methods will effect the performance of the items.

I have been told of some old sodium nitrate flare compositions, extreme lengths were go to to seal the devices and yet they still had a very short shelf life.
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#3 seymour

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Posted 07 April 2010 - 10:29 AM

In Sodium nitrate, Strontium nitrate ect, even low levels of impurities have a very significant impact on the hygroscopicity. Madly recrystalising will help, and possibly hugely.

As for sugar, have you considered abandoning Sucrose for a non-hygroscopic sugar? Sorbatol, while not really a true sugar, but a sugar alcohol is used by the rocketry types, not just because it is much less hygroscopic, but it has a much lower melting point, and is therefore safer to cast.

I'm not sure the composition that youare using your Sodium nitrate in, but treating it like some Ammonium perchlorate/metal compositions may help. When I first experimnted with AP compositions I made a lovely purple that contained (uncoated) MgAl. I made a mistake by adding water to make it in to stars, and almost instantly it expanded like foam and a cloud of Ammonia so thick that it was visable came forth. I just stood back and contemplated my loss, and have not used water in such mixtures since!

More recently I made another composition containing AP and uncoated MgAl.

Green
47% Barium nitrate
23% Magnalium
17% Ammonium perchlorate
9% Parlon
4% Nitrocellulose

I roasted the AP and Barium nitrate at 80 deg C to thoroughly dessicate them, and then after cooling them, quickly mixed them with the other powders and bound the mixture with the NC. Since they were pretty much dry inside, the NC was able to supress any reaction perfectly for the eight months I kept the stars. A few of the stars were kept in the open air in high humidity, but still were unaffected. It was a shame that the 23% MgAl content seems to cause BaCl to dissociate much like high temperature blues. The green was not very good.

Similar practices, and the use of NC to bind Sodium nitrate could be very effective, though I'm sure they will still have a shelf life, even if it is much extended.

Edited by seymour, 07 April 2010 - 10:37 AM.

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#4 pyrotechnist

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Posted 07 April 2010 - 11:23 AM

Its a shame because it seems some of the best chemicals are hygroscopic. Sodium nitrate seems to make a great strong yellow and even helps with oranges when dry. I am determined to find some sort of water proofing way lol as I am sure any fireworks with the stars in would just become water logged sooner or later. I may try the NC approach after drying to see how long they last in the open air which where I live in Manchester is always humid. The second option will be to coat the powder in 1 or 2% by weight with wax, could linseed oil be used?
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#5 digger

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Posted 07 April 2010 - 11:51 AM

In Sodium nitrate, Strontium nitrate ect, even low levels of impurities have a very significant impact on the hygroscopicity. Madly recrystalising will help, and possibly hugely.


I agree a high quality strontium nitrate makes a vast difference due to calcium nitrate contamination. However I guess there is little that is possible in the case of sodium nitrate, no matter how pure it will always be highly hygroscopic.
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#6 Potassium chlorate

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Posted 07 April 2010 - 03:53 PM

In Sodium nitrate, Strontium nitrate ect, even low levels of impurities have a very significant impact on the hygroscopicity. Madly recrystalising will help, and possibly hugely.

As for sugar, have you considered abandoning Sucrose for a non-hygroscopic sugar? Sorbatol, while not really a true sugar, but a sugar alcohol is used by the rocketry types, not just because it is much less hygroscopic, but it has a much lower melting point, and is therefore safer to cast.

I'm not sure the composition that youare using your Sodium nitrate in, but treating it like some Ammonium perchlorate/metal compositions may help. When I first experimnted with AP compositions I made a lovely purple that contained (uncoated) MgAl. I made a mistake by adding water to make it in to stars, and almost instantly it expanded like foam and a cloud of Ammonia so thick that it was visable came forth. I just stood back and contemplated my loss, and have not used water in such mixtures since!

More recently I made another composition containing AP and uncoated MgAl.

Green
47% Barium nitrate
23% Magnalium
17% Ammonium perchlorate
9% Parlon
4% Nitrocellulose

I roasted the AP and Barium nitrate at 80 deg C to thoroughly dessicate them, and then after cooling them, quickly mixed them with the other powders and bound the mixture with the NC. Since they were pretty much dry inside, the NC was able to supress any reaction perfectly for the eight months I kept the stars. A few of the stars were kept in the open air in high humidity, but still were unaffected. It was a shame that the 23% MgAl content seems to cause BaCl to dissociate much like high temperature blues. The green was not very good.

Similar practices, and the use of NC to bind Sodium nitrate could be very effective, though I'm sure they will still have a shelf life, even if it is much extended.


Hardt Green #6 will give you a beautiful green, though you must have barium chlorate for it. On the other hand no AP will be required:

45% barium chlorate
18% potassium /per/chlorate
6% red gum
3% charcoal, air float
11% magnalium, -200 mesh/<74µm
12% parlon
5% dextrin

You might bind it either with parlon or dextrin.
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#7 seymour

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Posted 07 April 2010 - 08:14 PM

Hardt Green #6 will give you a beautiful green, though you must have barium chlorate for it. On the other hand no AP will be required:

45% barium chlorate
18% potassium /per/chlorate
6% red gum
3% charcoal, air float
11% magnalium, -200 mesh/<74µm
12% parlon
5% dextrin

You might bind it either with parlon or dextrin.


That would be a lovely green, though I personally would much rather use one without all that Potassium. The lilac colour given off from it does affect the purity of the green flame, and since it is not needed, especially at 18% I don't see any really good reason to include it.
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#8 Potassium chlorate

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Posted 07 April 2010 - 08:22 PM

You could probably change the formula like this:

50% barium chlorate
8% red gum
5% charcoal, air float
14% magnalium -200 mesh/<74µm
18% parlon
5% dextrin

Probably. Posted Image
"This salt, formerly called hyperoxymuriate of potassa, is
used for sundry preparations, and especially for experimental
fire-works."

Dr. James Cutbush

#9 pyrotechnist

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Posted 07 April 2010 - 10:45 PM

Can we get back on topic, discussing colours is great and all but the main point of this is to try and find away of getting the chemicals that produce some of these great colours sealed from outside condensation and not walking back to mush or a fire!
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#10 Potassium chlorate

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Posted 08 April 2010 - 06:54 AM

Can we get back on topic, discussing colours is great and all but the main point of this is to try and find away of getting the chemicals that produce some of these great colours sealed from outside condensation and not walking back to mush or a fire!



Of course. I heat hygroscopic chemicals in the oven at 100oC, usually for 2-3 hours. After that I use them in compositions that aren't using water as a solvent (of course) and a binder that can resist moist, like parlon in acetone/ethyl acetate or shellac in ethanol/methanol.

If I make organic stars I sometimes, depending on the composition, heat them very carefully in the oven too, though this is not recommended on a larger scale. It should be done after they're dried, of course, since it would be madness heating stars still containing acetone, alcohol etc.

Parlon stars will take up almost no moistuire from the air after finished, while some shellac stars take up as much as 10% of their weight in water within 12 hours.
"This salt, formerly called hyperoxymuriate of potassa, is
used for sundry preparations, and especially for experimental
fire-works."

Dr. James Cutbush

#11 pyrotechnist

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Posted 08 April 2010 - 10:30 AM

Im assuming you can also add double the protection by using parlon and NC lacquer which with its acetone content should help bind the parlon. I am still not for certain how none-hygroscopic sorbitol may be though, been looking at patents for making none-hygroscopic sugars but they arnt really of much help. I may try coating some dried out sugar in linseed oil or wax by 2% of its weight and subtracting that from the main formula.
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#12 Potassium chlorate

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Posted 08 April 2010 - 12:10 PM

Im assuming you can also add double the protection by using parlon and NC lacquer which with its acetone content should help bind the parlon. I am still not for certain how none-hygroscopic sorbitol may be though, been looking at patents for making none-hygroscopic sugars but they arnt really of much help. I may try coating some dried out sugar in linseed oil or wax by 2% of its weight and subtracting that from the main formula.


I actually used NC-laquer in acetone for some stars and they worked out really good. Then I primed them in meal powder+10% German Black, also in NC-laquer. Using NC-laquer for the priming is very good both for protection against moist and for reliable ignition of the stars.
"This salt, formerly called hyperoxymuriate of potassa, is
used for sundry preparations, and especially for experimental
fire-works."

Dr. James Cutbush

#13 pyrotechnist

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Posted 08 April 2010 - 12:21 PM

Mite try that, thanks, not sure if you can get good performing fast R-Candy using NC as a protection but I may try that also.
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#14 pyrotrev

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Posted 08 April 2010 - 12:23 PM

Sodium nitrate can just about be used if it's REALLY pure and if you don't use water when making stars. I suspect the problem with a lot of commercially available stuff is sodium chloride impurity.
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#15 dr thrust

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Posted 08 April 2010 - 09:25 PM

mybe you can use marshmallow as a binder for your candy rocket, :P




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