hard grained BP?

[Blackthumb]

Want to share your secrets for making Hard Grained BP?

[Mia]

We have had very good results with the addition 3% per 100 grams using phenolic resin rock hard results and burn speed more or less the same

[Potassiumchlorate]

Press it to pucks. Crush the pucks. Sieve out the grains.

[Mia]

Pain in the arse to do though (press puck tooling) and all that eligibly the sulphur becomes more elastic under pressure hence the bond

[Algenco]

use hot charcoal and 5% binder

[Mia]

A hotter charcoal would not equate to a harder grain a binder yes.

[Potassiumchlorate]

Pain in the arse to do though (press puck tooling) and all that eligibly the sulphur becomes more elastic under pressure hence the bond

 

I hate the work, but the result is very satisfying.

[nater]

I have found that I get the hardest grains when the BP+binder is mixed on the wet side and rapidly dried in the hot, high, summer Sun. If the granulated grains are spread out as thin as possible, it doesn't take long to dry and the grains are crunchy.

 

I have never tried to corn BP, so I cannot compare my method to that.

Edited January 28, 2013 by nater

[Algenco]

A hotter charcoal would not equate to a harder grain a binder yes.

 

extra binder won't slow BP made with hot charcoal enough to notice

use 5% dextrin in BP with commercial mixed hardwood charcoal and you'll see a big difference

[flying fish]

What about pre-dissolving the binder in the solvent instead of adding the solvent to BP+binder? I know a lot of guys who swear by that method, as you don't have to over-wet to fully "activate" the binder.

 

That's essentially what I've done for years with NC lacquer and it has worked great (even though I wouldn't necessarily make a direct comparison to an aqueous binder). As I'm starting to value the brain cells I have left I think I'm going to switch to something aqueous

[nater]

What about pre-dissolving the binder in the solvent instead of adding the solvent to BP+binder? I know a lot of guys who swear by that method, as you don't have to over-wet to fully "activate" the binder.

 

 

That is on my "to-try" list, but I haven't done it yet. I think I get better grains when they are granulated with comp on the wetter side, otherwise it comes out dusty or more fines that I like. However, my experiences are far from the final word on the subject. I welcome to be proven wrong!

[AirCowPeacock]

I use it. What I suggest to get the consistency right is to disolve the binder (dextrin) in what should be about half of your solvent (water.) Mix thouroughly and add more solvent (water) until the right consistency it reached.

 

That is on my "to-try" list, but I haven't done it yet. I think I get better grains when they are granulated with comp on the wetter side, otherwise it comes out dusty or more fines that I like.

 

That's because you havn't properly disolved your binder until it's over-wet.

[marks265]

I use 5 percent dextrin and it goes in my mill jar along with the other ingredients. I don't use alcohol and I don't use home made dextrin (anymore). I also purposely wet it a bit more than I should if I want harder grains and screen it more times before final granulation. I also use boiling hot water. It is my personal belief that dextrin and maybe the other chems need more soak time to get each chem to do their part. This thought mainly pertains to two things which are; the interaction of the nitrate with the hot water and the charcoal, and the activation of the dextrin to its fullest potential.

 

Even though homemade dextrin can work. It is way too much of a shot in the dark to know how much of the starch converted. This is why I now use commercial dextrin. Others may have their own work around to make this happened but as a purist approach to finding the hardest granules commercial is the best way. I suppose that this doesn't mean that I could get a bad batch of dextrin which would be an exception to the idea.

 

Powder should be cheap, quick (within reason), and easy to make because it is the main staple of what we do. Using red gum, alcohol, exotic binders, and special elixirs are not what black powder is all about. Corning is way over the top as well. If we were talking ballistics or something where keeping accurate grain size is of high priority then I would give in on the corning idea.

 

These are my deepest darkest secrets as well as my 2 cents.

[Blackthumb]

Thanks for all the replies. Think I have a bad batch of powder....took 25g 3f to get a 40g round to height!!! About twice as much as ordinary. Think it might have been the sulfur. Ran out of the good stuff and bought off the shelf powdered sulfur 99.5% for garden use.....

Powder burns open quite well but just doesnt have the "umpf"!!!

[dynomike1]

You could be right, but don't throw it away use it for burst and put a booster in it. I seem to be having trouble w/ my grains being hard as before could be some bad Dextrin, i am still making 8oz. batches so the last batch instead of .8oz. (5%) i put .9oz. in haven't granulated it yet.

[Blackthumb]

I'll keep it and use it...it's just not right. I make 10# at a time. Gonna brew another batch today...

I doubt if it is the sulfur...

[pyrojig]

Usually it is not the sulfur. I have used Ag grade sulfur for many years., and have extremely hot bp. Side by side with rubbermakers sulfur showed no diff in performance.

Wetting is the key to hard grains, and a good binder (dextrin works great, I have been using homebaked for years. If you do it right it is par with the stuff on the market)

 

I agree with Marks265. Powder is a staple in our hobby. It should be made cheap,easily, and effective with the least amount of energy, and materials. I too have experimented over the years with many types of binders and expensive methods to get explosively fast bp, only to end up sticking with the K.I.S.S. theory( keep it simple stupid) ! In most instances hot bp is to hot for most applications. It is good for burst, but hard lifts break shells , and hot bp catos rockets. It seems best to stick to the basics and keep it cheap. This becomes more important when your making close to/ or over 100# /yr.

[Oinikis]

for what aplications you need to use rock hard grains? i've always granulate it without a binder, and they seem ok to me, and do not break very easily.

[Potassiumchlorate]

One more thing: I use 30 ml of water/alcohol, about 65:35 per volume, per kg though with a powerful enough press, you don't need any water or alcohol at all.

[Mumbles]

To me, hard grained BP is crucial when building cylinder shells. You don't want the BP burst or the polverone filler to be able to be crushed during filling, handling, or shooting. It's very important that cylinder shells are solidly filled for proper function and to safely get out of the gun. I prefer it for lift too. Sort of for the same reasons, I like knowing what grain size I put in will still be that size when it's fired and not crushed during handling or transport.

 

Water on it's own does give fairly hard grains, but I still prefer a little binder to give even more strength. Red gum is probably the worst offender for giving soft grains in my experience. The amount of red gum required for strong grains slows the BP down too much, so people tend to use less than an optimal amount resulting in softer grains. Pressing also makes very hard grains, and the sizing is very stable if it has been tumbled to break off any weak spots around the edges.

[Potassiumchlorate]

Once upon a time all shells were filled with grained BP, weren't they? You don't have to go back longer in time than to Weingart. Shells in the old days were filled with stars and a small, weak burst charge of corned BP. Must have been heavy for the bigger ones.

[Mumbles]

You don't have to go back in time at all really. At least many American products are still lifted with corned BP. I don't know what sort of shit the Chinese are using currently though. For a commercial operation, it doesn't make economic sense to make your own BP for the most part. Sure it's cheaper, but also relatively dangerous, time consuming, and a huge commodity. You'd have to have full time staff around just to make BP for you. It's easier in the long run to purchase commercial BP and use it for lift, if not burst as well.

[Blackthumb]

Mumbles...you and I agree on reason for hard grains. Still can't quite get to the same burn rate as commercial BP. Had to use 35 gns to lift a 2 1/2" round shell. OK though since I make my own in large quantity. Maybe pauwlinia would help? Made another 5# w/dextrin 5% and am going to tumble the 2 and 3f grains a bit....

[AirCowPeacock]

If your BP isn't good enough, you're probably not using the right charcoal. No need any charcoal you can't make yourself. I promise you there's plenty of good wood right next door. I use the buckthorn that dominates my back yard, I also pick up willow just a few miles from home. Theres plenty of other great options around, but these are the most available for me.

[dynomike1]

As dirty as i get making BP or star comp there is no way i'm going to make Charcoal. I'ts to cheap to buy. Pauwlinia is what i am using and it BP burns right with Shuetzin 1FG.The only way you could even think about coming out on Commercial BP is to pick it up, you know it's $39.00 shipping and anywhere from $13.00-$23.00lb.. Edited February 4, 2013 by dynomike1