55 replies to this topic

[Niall]

Certainly interesting documents, sadly they lack detail for our purposes. Are there any like that wrt BP? Or do you have access to any of that sort?

[rocketpro]

Quote;

 

Single Component Milling

Single component milling involves milling the charcoal, sulfur, and potassium nitrate separately and then mixing them together.

Before describing this process, dispelling a common myth is in order here. This concerns three component milling and what actually happens during the milling process.

A common misconception is that milling sulfur and potassium nitrate together with charcoal has the effect of pressing the other components into the charcoal. This doesn’t happen because the tiny holes (or pores) in the charcoal are too small to accommodate the sulfur and potassium nitrate particles. This pressing process thus happens neither during milling nor during subsequent pressing.

So what is there to be gained by milling all three components together if this effect does not happen? Plenty, because the milling process is also a mixing process. It is actually this mixing process that is the critical factor in ensuring that the Black Powder is properly incorporated. Understanding this concept is the key to understanding how good powder can still be made without three-component milling.

Milling typically takes longer than mixing. In fact proper mixing mostly takes place when each component has been milled fine enough to ensure good intimate mixing. This is one reason why those who favor three-component milling often opt for a pre-milling process of milling the individual components before milling them together.

It makes a lot of sense to mill the components individually for a long length of time and then mix them for a shorter time period. For example one could mill each component for three hours and then mix them together by milling them together for about an hour. This process still involves three-component milling, but for a shorter time period. The shorter this time period is the less chance there is of the mill exploding.

The just-mentioned method uses the ball mill in the final mixing stage, but unfortunately creates the situation where one has had to revert to three-component milling. This three-component milling is for a shorter time period but it is still three-component milling. Are there any alternatives? Yes, there are.

Mixing can be done by sieving the three components together. The more one does this, the more intimate the mix. Alternately, one can sieve the charcoal and sulfur until they are thoroughly mixed and then sieve them together with the potassium nitrate. The mixing process can also be varied by stirring the components together with wooden spoon.

But just as ball milling beats hand grinding, doing the mixing in a ball mill beats doing it by hand.

One may opt for another solution by doing the mixing in the ball mill but without the balls. This reduces some of the dangers created by the milling media but also reduces the mixing efficiency. Reducing the efficiency means having to increase the mixing time. Increasing the mixing time increases the danger of an accident.

Other problems can occur with single component milling. Sulfur for example, can build up a static charge if milled on its own. This charge is dissipated if charcoal is added to the sulfur and both are milled together. Potassium nitrate milled on its own presents another problem. The finely milled potassium nitrate particles have a tendency of clumping together if not mixed with another substance. These problems are addressed in the following sections.

Double + Single Component Milling

This section discusses double plus single component milling. The double part is a mixture of charcoal and sulfur, while the single part is potassium nitrate. The charcoal and sulfur are milled together and then mixed with the potassium nitrate that has been milled on its own.

Note that this process only considers mixtures of charcoal and sulfur and not the other possibilities such as potassium nitrate and sulfur or potassium nitrate and charcoal. The reason for this is safety.

Before milling the charcoal with the sulfur, it is a good idea to reduce its particle sizes. A good way of doing this is to sieve the charcoal through a 50 mesh or finer sieve before mixing it with the sulfur.

This process reduces the chances of a static charge being built up on the sulfur but does not address two other important issues.

The first issue is the problem of the tendency of finely ground potassium nitrate to agglomerate. This is the process whereby the particles tend to clump together. This can be quite a serious issue, but it can be solved by mixing some charcoal with the potassium nitrate.

The second issue relates to the danger of spontaneous ignition when the finely ground potassium nitrate is added to the other components, also finely ground. I am really not sure how prevalent this danger really is. French powder makers seemed to think so. This caused them to opt for the solution described in the next section.

Double + Double Component Milling

The perceived dangers in the last section can be got around by creating two double component mixes: potassium nitrate + charcoal, and charcoal + sulfur.

Potassium nitrate with charcoal is potentially nearly as dangerous as a three-component mix if the ratios of potassium nitrate to charcoal are in critical or near critical proportions. Typically these ratios vary between 4:1 and 6:1. Mixes in this range of ratios have the potential of igniting easily and burning very efficiently.

We get around this problem by increasing the ratio of potassium nitrate to charcoal to a ratio of 15:1. Thus if we are working with Waltham Abbey proportions we take one third of the charcoal and mix this with the potassium nitrate. The remaining two thirds are mixed with the sulfur.

 

Edited by rocketpro, 08 February 2015 - 12:01 PM.

[Niall]

I need to return to this, but there are items that I clearly will strongly disagree with here. The difficulty in the 'myth dispelling' is the nature of intimacy, which is the intrinsic nature of the mixture.

The latest thinking I'm aware of is that this 'myth' is in fact current knowledge and accepted as such by academia. Not that this proves it.

With respect to the author of the quote, there is some glaring errors in his claims of sizing and occupation. Blinding errors. This man doesn't seem to be a chemist. I'm probably wrong.


The best way to resolve this would be for people to try for themselves, rather than take my word for it.

'It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong.'

Richard P. Feynman

Edited by Niall, 08 February 2015 - 12:35 PM.

[Niall]

Error posting

Edited by Niall, 08 February 2015 - 12:26 PM.

[rocketpro]

That page was from;

 

`Black powder Manufacturing Testing and Optimizing`

 

By Ian Von Maltitz 208 pages

 

ISBN No 0-929931-21-1

[Niall]

Yes, I found it. Thank you. I'm going to have a look over it better. But it doesn't seem to line up with a few things.

I'm going to check first before making myself look like a bigger goon!

[Niall]

I am completely satisfied that the author is inaccurate. For reasons I will return to.

In the meantime (sorry I'm meant to be working!!!)

1. Consider the smallest possible size of a chemical.

2. Why would willow appear to be better than a softer wood?

I hope my response isn't rude, I'm enjoying this conversation more than my work!!!!!

Edited by Niall, 08 February 2015 - 01:20 PM.

[cooperman435]

Very well written responses, it's like being back in the good old days when we actually had blokes on here talking about things that mattered! :-)

Without any particular testing myself I do tend to lean heavily towards Niall's opinion/belief/results of testing that finely milled kno3/s mix then added to c will encourage a more intricate mix, I once had strange results when granulating after I had over wet my batch, continued adding dry mill dust to help dry out the mix and after granulating had FAR faster powder than normal, indeed faster than the rest of that very batch that had been dampened "correctly"

I put this result down to partially desolved kno3 being suddenly brought out of suspension and resulting in tiny crystals dispersed very well (maybe in the charcoal too) in the mix. Certainly made a noticeable difference in burn speed and power.

[Niall]

On the money again! This is the 'grab' of the solvent. Once exhausted, anything else you add will not be grabbed! For this reason I pre-dissolve binders in solvents prior to adding to comps. This stops the solvent grabbing easier solubles and destroying your hard word. The difference is often astounding.

I really should be working......

Edited by Niall, 08 February 2015 - 03:14 PM.

[rocketpro]

Yes, it is an interesting subject for sure Phill.

 

Some years back I spent many hours on obtaining reliable fast powder.

I found Paulownia and Willow charcoal to be very fast and best for my needs.

I also tried Balsa charcoal, but it was frighteningly fast, too fast in fact!

Edited by rocketpro, 08 February 2015 - 03:37 PM.

[Niall]

Interesting! I feel there is a speed, beyond which, the powders become less useful, especially for passing fire. They go off so quick that the heat is built and diminished before the next fuse/prime can ignite. It's always fascinating to push it though and see.

I too tried balsa, and as you say, it is frighteningly fast, a Buggerance to make too, loads of wood and all you get back is something black in the very bottom of the tin!

I will respond properly to the 'black powder optimising' quote properly tonight. I'm not avoiding it, it just requires quite a specific and measured response to do justice to my position.

[martyn]

Whilst I agree that it's fun to play around trying to make bp as fast as possible, the bottom line however is that for most purposes, it doesn't have to be super dooper, it just needs to be good enough, and consistency is more important than speed. You can always use a bit more if need be. Not knocking you speed freaks though, very interesting following the thread. Have any of you tried wet milling, or milling, granulating and then re milling?

[rocketpro]

 Have any of you tried wet milling, or milling, granulating and then re milling?

I haven`t tried any of those options - mainly because the BP was fast enough as it was so any further effort for speed was unnecessary. I try to make everything as simple as possible (mainly because I hate ball milling) so from the very beginning I only acquired chems in an already `flour like` state with willow milled to air-float. BP made this way is more than adequate and very convenient - once 23% water is added and the mix is granulated & dried a 0.5g pile of it goes off with a satisfying thump with barely any residue left behind - apart from a smoky grey patch 4" - 5" in diameter. 

I do have some double-double mix. It is fractionally faster than the above mix but not enough to warrant the extra milling.

 

P.S. I too had noticed a speed increase like Phill mentioned when I re-wetted and re-granulated a previously wetted granulated mix.

Edited by rocketpro, 08 February 2015 - 05:43 PM.

[Deano 1]

I have noticed a difference when I press my pucks and granulate, the powder that is left I re-press into pucks and granulate again (with 5% water/alc). This second and sometimes third pressing really does make a difference, not just speed but it tends to burn cleaner, not sure how that works.

[Arthur Brown]

Slow burning powder can spread itself out as mass makes gas, leaving a patch of unburned matter where the powder went cold before burning, in a faster powder mass turns to gas before other mass has moved out of the way, so all of it burns and none is left behind