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Why binder in bp?

Bp binder Bp making

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#1 kingkama

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Posted 10 October 2018 - 01:18 PM

I newer added binder in my bp i tried dextrine but It slow bp a lot, so i use only water or acetone or alcool or a mix of them. Bp grain are hard and the performance endure in the time. So why add binder.

Recipes i use are:

75-15-10 Willow
74-14-12 "
72-20-09 wine
68-16-16 Willow

KNO3-charcoal-sulfur% kind of charcoal

First 3 four hour mill
Last One One hour mill

#2 Arthur

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Posted 10 October 2018 - 03:42 PM

Traditionally BP was made from wheel milled powder pressed into big cakes then broken (corned). This yielded a large variety of sizes of hard particles from blow away dust to 0FA. Amateurs don't usually have a press, so usually granulate the milled product, which produces a weaker grain structure. To increase the grain strength binder is added  which usually hardens the grain but slows the burn. The granulating method usually determines the particle size distribution.


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#3 Lozzard

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Posted 10 October 2018 - 03:42 PM

What percentage of dextrin were you using ?

 



#4 Lozzard

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Posted 10 October 2018 - 03:46 PM

i have never really noticed that dex reduces my burn rate ? I always granulate execept if im coating rice hulls i use meal but still add 3% dex.I have been using box elder for char on last few batches .



#5 MadMat

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Posted 10 October 2018 - 05:51 PM

I make my BP without binder, but as mentioned, I have a press. I dampen my mill dust with 80% water/20%alcohol and press into pucks. I then semi-dry these pucks and break them up and size the granules. I tried making a batch with dextrin (3%) and granulating.  I then ran ran baseball tests to compare  BP with and without dextrin binder. There was a very slight difference with the advantage going to my BP without dextrin. I have to stress that the difference was VERY slight.



#6 kingkama

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Posted 11 October 2018 - 12:20 AM

I used not much than the 3%, but I don't see the vantage of corning or binding bp(except if you want to use it in a gun) water make alone a good work (hard grain) , using acetone or alcohol you have a less denser BP but much faster,so I write this post to know other opinions.

Edited by kingkama, 11 October 2018 - 12:30 AM.


#7 dagabu

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Posted 14 October 2018 - 01:18 AM

A few things to consider with your original question, why use a binder?

 

Hard grains are not achievable unless something is holding the chems together. Water allows the KNO3 to dissolve and as the crystals reform, they can help hold it together but they will crumble if pinched hard.

 

The binder has to physically bond the chems together to make hard grains, too little and the grains disintegrate and too much causes flame retardation and 'slower' powder. Most people find that their binder is sufficient with just 1.5-2% added while milling and 3-4% may be needed if added to the powder and screened in.

 

Most of the time, especially with smaller shells, the size of the grain is not as important as the weight of the charge when lifting or breaking the shell but if the surface of the powder is too great, the lift may cause a flowerpot or the break may cause the stars to fly blind.

 

If solid BP grains can be made consistently, sized by screens and used in a consistent way, your shells will lift and break more consistently as well. 

 

Categorize your powders for the need, 2FA, 4FA, MealD and throw the rest back in to the next batch of BP. 


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#8 kingkama

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Posted Yesterday, 09:21 PM

Usefull information dagabou,i forgot to follow the rule of the sorting and grain durability, hard grain are omogeneous and predictable, Dextrine or red gum made a big difference from water granulation.
Thank's for the insight.

#9 Arthur

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Posted Today, 12:33 AM

deleted


Edited by Arthur, Today, 12:37 AM.





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