BP - Hardness

[DaMounty]

Hi,

 

I'm ricing my BP with +3% dextrin and wetting with 75/25 water/ISP. The pellets once dry crumble to dust when rubbed between my fingers. Is this normal?

 

Thanks,

...DaM

[FlaMtnBkr]

No it's not normal. My BP with no dextrin hurts my fingers when trying to break apart.

 

How much water did you add? What was the consistency like? Clay, dough, wet sand, etc?

 

You might want to try making dextrin liquor. Add 10% dextrin to water so you know it's activated and then add about 20% of this solution to your BP. This will give you 2% dextrin that is completely activated.

[nater]

I second using the dextrin liqour method, it works great and is how I normally granulate BP. I make the solution as FlaMtnBkr mentioned, mix enough in with the BP until it feels like modeling clay and then granulate.

 

Have you tried using less alcohol or just plain water? Too much alcohol can interfere with the dextrin being activated.

[DaMounty]

The powder was the consistancy of play dough. To be honest I have not been measuring the amount of water/ISP being added, just spray mix, spray mix until desired consistancy has been reached.

 

CouldI I re-mill the powder then try again with the liquor method? - only water no ISP

 

I have been making 8 oz batches, so I will add 20% of the liquor (approximately 1.6 oz) to the batch.

 

Much appreciated everyone.

 

DaM

[braddsn]

DaMounty, something to consider... I once got about 4 lbs of bad dextrin. I know it sounds far fetched, and almost impossible, but sure enough, it ended up being the culprit for a LONG list of headaches that I couldn't figure out. Where do you get your dextrin? Or do you make it yourself? Getting bad dextrin I would say is very rare.. but it can happen. And when it does... grrrrrrrrrr it's bad news!! Your granules of bp should be almost literally as hard as rocks when done right.

[Arthur]

Get different dextrin from a different supplier. remill what you have and add 2% dextrin before milling. put the milled powder into a snap top bag with a little water, and let it stand (2 - 24 hours) keep mixing it through the bag (it's cleaner) when you have it evenly mixed and evenly damp so that it just holds together then rice it.

 

Remember that it takes a long time for the grains to actually dry hard, patience is a virtue here don't hope to rush it.

[FlaMtnBkr]

I think I have to disagree about the BP grains taking a long time to dry. Yes they can, but you should be drying them as quick as possible. If you make 1/4" layers and put the trays in the sun and maybe even use a fan they can be dry in just 2 or 3 hours.

 

When it takes a long time to dry the nitrate crystals grow and get bigger which slows the powder down. Hot powder can turn into weak powder if it stays wet too long. And the nitrate crystals that you worked hard to get small in the mill will grow and that effort is wasted.

 

If I wet my BP to a modeling clay consistency and granulate I get grains that are plenty hard without the use of a binder. I have mentioned this quite a few times and no one has ever verified or disputed the claim so I don't know if I'm doing something different? But it's always worked and it has worked with every charcoal I've tried and the grains are sturdy enough to hurt my fingers when crushing a large clump. I used to mess with dextrin in my BP but when I made BP for rockets without it I didn't see the need and haven't used it in over 10 years now.

[DaMounty]

So with the proper amount of water the BP granules should be hard, even with out the use of a binder.

 

Is 20% of the weight in water the rule of thumb?

[nater]

Yes. In my experience the granules are hard enough for our uses without a binder. I do notice some dust forming when it is stored for some time, but it is still functional. Dextrin makes the grains even harder and more durable.

 

One thing I like about making a BP base without a binder is I can use it for more things. By adding metal or more charcoal it can become stars, gerbs, rocket delay, etc...

 

20% of your solvent in the comp is a general amount for granulation. The right amount can change based on the type of charcoal, the humidity when you are working and how dry your chems are to begin with. I aim for a somewhat glistening, modeling clay consistency. It can help to keep a little dry comp in a seperate container in case you over wet it. I have a bad habit of missing the line from too dry and ending up with charcoal soup.

[schroedinger]

You get hard granules from granulating your bp with water w/o dextrin or any other binder?

I only get ok granules if i use alcohol.

Best granules are formed if you corn your bp. There you need about 6-8% water and 2 % dextrin for good results.

[Mumbles]

Are you absolutely positive the granules are dry? They tend to be pretty weak until all the water is gone. One quick check is to put some in a plastic bag, and put it in the sun for a few hours. If there is condensation on the inside of the bag, then you're not quite dry yet.

 

Even with the worst dextrin I could cook myself, I always managed to get hard BP granules. The same may not be true of stars though, since they're bigger and require more structural support. I've never really tried to make BP granules without a binder, but can certainly believe that they're hard enough on their own.

[rogeryermaw]

If I wet my BP to a modeling clay consistency and granulate I get grains that are plenty hard without the use of a binder. I have mentioned this quite a few times and no one has ever verified or disputed the claim so I don't know if I'm doing something different? But it's always worked and it has worked with every charcoal I've tried and the grains are sturdy enough to hurt my fingers when crushing a large clump.

 

+1 i never use binder granulating black powder. and i barely use enough water to get it to stick together in a ball. after drying over night, the grains are plenty hard and never had an issue with performance.

Edited April 20, 2015 by rogeryermaw

[DaMounty]

Thank you to all who replied. I am now using the liquor method and patently waiting for powder dry completely. Great results.

 

Thanks again the help is greatly appreciated

 

DaM

[Ubehage]

I have got my best results by using a 2% Dextrin-solution in 75/25 water/alcohol.

I use about 30% solution in the composition, meaning that for a 1kg-batch I would use 300g of liquid.

This gives the composition a consistency of moist sand - wet, but in no means liquified.

I then turn it for a few seconds on a heating-pan (105 C), before granulating and leaving it to dry on a piece of kraft-paper.

 

My method is evolved from trying out all the different normal methods I could find.

This one works best for me, and gives me rock-hard granules.

Edited May 22, 2015 by Ubehage

[DaMounty]

Update,

 

Just as i finally got my BP into nice hard granules, I completed my ball mill. Holy liften - I am now out of the stone ages (hand mixing BP). So I milled all previous batches and riced them all again, hoping to have a video up this weekend of some burn tests. What a difference milling makes.

 

Now on to making some cut stars using the recipe from Turbo pyro. But a quick question. In the recipe it calls for +10% water to be added to the composition, for pumped stars. I do not have a star pump as of yet thus the cut stars. Would I still dampen the mixture to +10%?

 

As you can tell by my posts I am very thorough and like to take my time and understand and learn the techniques. Hence no shells fired yet. Coming in time.

 

 

...DaM

[Mumbles]

For cutting stars, you will need to use more than 10% water. The exact amount varies composition to composition, and day to day. You need to go by feel and experience. If you're planning to make a patty and cut it, I normally start around +20% water. From there you can slowly increase the amount of water until it's about the consistency of clay. I like to compress it into the bottom of the container I'm using to mix and let it sit for a bit. This gives the binder enough time to totally activate. I will then make a cross shaped cut, or a few cuts all crossing through a common point like a pie. If the cuts are clean, and don't crumble where the cuts cross, you're ready to go. I tend to make my stars a bit wetter than others. You can get by with drier.

 

If you're using a loaf box, you don't need as much water. 20% may be too much for this in some cases.

[Arthur]

With small amounts of water I tend to leave the damp mixture in a snap top bag for a day or so, the time assists getting the moisture content uniform through the batch. This helps with BP because it all granulates without crumbling and with stars because they all have just enough moisture to bind -but neither takes too long to dry.

[DaMounty]

BP Test 3g meal (right out of the mill) charcoal - cedar 2x4

http://youtu.be/wKT9Pz5H53Y

[DaMounty]

a pic of the fuse placement for the above video

 

[DaMounty]

A screen shot from today's baseball tests

[DaMounty]

Ball weight 144g

BP 10% = 14.4g

flight time from launch to ground 8.2 sec. = 5.5 sec from apex??? (using 2/3 of 8.2)

 

I just need to figure out the hight calc. as I can not think of it at this moment

 

DaM

[Wiley]

That is some HOT powder! Nice work!