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Water temp with dextrin binder


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#1 BetICouldMake1

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Posted 08 August 2018 - 11:14 AM

I've seen recommendations for boiling water and room temp water as solvent. I know that KNO3 has higher solubility in warm water so is that the reason for binding with hot water or does the heat help activate the dextrin? 

 

Basically just wondering what the benefit (or potential drawbacks) of using hot vs cold water as solvent are. 

 

 

As a side note: is there a preferred way for newbies like myself to post multiple questions? I always do my best google-fu and forum search before posting, and I have started new posts rather than tack questions onto a single post since that seems like it would make it easier for other newcomers that might have similar questions to search for posts, but I also don't want to spam the boards with the 1000 questions I have. 



#2 Arthur

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Posted 08 August 2018 - 11:32 AM

Hot water can cook dextrin very quickly to a hard bound lump. Definitely the hardest stars I've made were dextrin bound with water from the kettle at coffee making temperature.  


Edited by Arthur, 08 August 2018 - 11:33 AM.

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#3 pyrokid

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Posted 08 August 2018 - 02:42 PM

I've never used hot water to activate dextrin. I bet it does result in a greater activation, but I've never had any problems with room temperature water. The use of boiling water adds cost and handling concerns to your process.



#4 Mumbles

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Posted 08 August 2018 - 11:17 PM

Hot water has advantages for a couple of things.  Namely blackmatch and polverone.  On a purely comfort level, it's way more comfortable to dunk your hands into warm comp than cold comp.  Potassium nitrate is endothermic when it dissolves.  If you have ever used room temperature water to wet a nitrate based composition, you may have noticed it's cool to the touch.  

 

Hot water dissolves more nitrate, and makes it a bit more fluid.  In my opinion, this helps to penetrate cotton string better for making black match.  Plus the previously mentioned point makes kneading it a lot more pleasant,  For making polverone, it can help to dissolve some coarse nitrate and generate a bit faster material.  It also may allow you to get away with a bit less water.  The hot water makes a good wet comp, which solidifies as it cools.  The repeated regranulation if you follow Mike Swisher's or Fulcanelli's instructions gives dry material in a day or two depending on what sort of atmosphere you're working in.

 

The same theory may apply to hurt black powder.  If you use hot water it may dissolve the very fine milled nitrate to generate larger crystals as it evaporates.  

 

Personally I use room temperature water for most everything.  The two exceptions are black match (mostly for comfort), and polverone as mentioned previously.  


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#5 Maserface

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Posted 10 August 2018 - 11:09 AM

I use boiling/hot water for polverone too, I didn't once, and ended up having a much harder time.  The tepid water batch I did resulted in a larger percentage of fines, and seemed more tedious when getting the moisture level correct for granulating.



#6 BetICouldMake1

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Posted 11 August 2018 - 10:02 AM

Thanks guys. The potential recrystallization of nitrate when making bp was exactly what I was wondering about. 



#7 AussieBombTech

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Posted 06 September 2018 - 05:38 AM

Thanks guys. The potential recrystallization of nitrate when making bp was exactly what I was wondering about.

I personally always use hot water and have never had a recrystallisation issue. If you don’t force dry it the crystal won’t fall out of solution due to thermal shock. That’s why you should only dry at room temp
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#8 flashcrazy

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Posted 02 January 2019 - 05:12 PM

i always use boiling water and add into and mix slowly until just enough to9 bind a ball together for granulation. always very hard grains and dries pretty fast in ambient air no dryer. just my 2 bits.



#9 dagabu

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Posted 02 January 2019 - 05:17 PM

Agreed.  :D


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#10 justvisiting

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Posted 02 January 2019 - 08:04 PM

A while ago the question (in a contest) came up whether or not you could make lift with commercial airfloat, without out milling it, or milling black powder. The potassium nitrate was pre-milled though. I did a bunch of experiments to try to 'win the prize', and was successful. The amount of hot water it takes to moisten black powder (or polverone) goes markedly down if you heat the whole mass, and give time to dissolve the nitrate and activate the binder. 

 

I used dextrin for my first tests, but I didn't think the screened grains met the requirement of 'reasonably durable'. I tried 3% dextrin to harden up the grains but the performance dropped dramatically. Later, I used CMC instead of dextrin. 

 

Since this was a contest, I had to pull out all the stops to make the mediocre charcoal work in the first place, without milling, even. Twice before, I had been able to make mediocre charcoals perform better by increasing the charcoal (70-20-10). It worked this time too. Part of the contest requirements was to distil the instructions down to a tutorial, which I did. It's here:

 

http://pyrobin.com/f...hells Using.pdf

 

My logic was to maximize the charcoal to oxidizer contact by using hot water and heating, and to increase the available fuel, to make crappy BP charcoal be less crappy if used to make lift. 

 

Note: If it hadn't been required to use such a poor BP charcoal (unmilled), increasing the dextrin to 3% should not have been a problem IMO.


Edited by justvisiting, 02 January 2019 - 08:10 PM.


#11 dagabu

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Posted 03 January 2019 - 07:47 AM

I've secretly coveted that idea since you brought it up last year. I hyper milled my chems for PGI last year and made a batch of BP for cohetes and it was too fast for the crappy tubes I was using.

Thanks for the link, I got a full bag of airflow from Karl to try this with too.

5% of CMC is a hell of a lot, did I get the math right? 10g per a 200g batch?
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#12 justvisiting

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Posted 03 January 2019 - 12:13 PM

Actually, it's 10 grams per 300 gram batch (additional), so just over 3%. 



#13 dagabu

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Posted 03 January 2019 - 01:01 PM

OOPS! Thanks for the correction. 


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