B2Crawler Posted November 8, 2015 Posted November 8, 2015 ok I have been making my black powder without a ball mill, its been working good, mostly been just using it for fireballs/minesI have been wetting it with regular rubbing alcohol to granulate, my question is can I or should I use MEK (Methyl Ethyl Ketone) instead of the rubbing alcohol, would it make a better green powder?
MadMat Posted November 9, 2015 Posted November 9, 2015 (edited) I'm not certain, but you might be disappointed with the performance of your BP using MEK. Are you adding any type of binder to your BP? If you use dextrin, you need the water present in the rubbing alcohol to activate the dextrin. Water and alcohol is the way to go. water activates the binder and the alcohol inhibits the solubility of the potassium nitrate in water, which prevents leaching out the KNO3 and recrystallization. Recrystallizing KNO3, especially slowly, will create large crystals of KNO3 and that will ruin the performance of the BP. Also, there is a maximum percentage of alcohol (25%?) that can be used or it will stop the dextrin from working. Personally, I use 80/20 water/alcohol. I don't use any binder. I then press the wetted BP into pucks then corn it. Though I can't think of any offhand, I know there are binders that could be activated with MEK, so I guess it's possible, but I think you are better off keeping to the alcohol/water. Edited November 9, 2015 by MadMat
B2Crawler Posted November 9, 2015 Author Posted November 9, 2015 Thanks, yes I am using dextrin, I made a few batches without dextrin but I found that the grains would start to crumble smaller into powder the more I tried to compact it into anything, with the dextrin it really holds it shape a lot better, harder grains, I was just curious about the MEK, I had some laying around in my shop, I'll stick to the alcohol, Thanks.
Arthur Posted November 9, 2015 Posted November 9, 2015 Probably you'd find it cheaper to get a small rock tumbler than continue to use alcohol for long.
niskahiki Posted January 3, 2016 Posted January 3, 2016 How much Dextrin is needed for example 100g BP? D does not dilute to the alcohol, i wonder whats the purpose to use alc?
schroedinger Posted January 3, 2016 Posted January 3, 2016 If you use dextrine use +2% Dextrine. +5% can be used for extra strong grains, if performance decreases is not a issue.Use water to wet yor powder and distribute ut by screening the bp through a 4-8 mesh screen. The ammount of water you need depends also on the method used. If you rice (screen granulation) you will need about 10-15% water. Wet thepowder to a state where you can form apple sized balls that don't form worms if pushed through a sieve. If you corn (pressing pucks and crushing them up) you need 5-8% water. If you use dextrine S binder in bp you don't need alcohol. If have problems with wetting the comp use 5% alcohol to brake the surface tension. If you wan't to use alcohol you either need to add 4% red gum, or resinox (or other alcohol, based binder) or you need a charcoal with good resine content (Works knly good with the homemade pyro charcoals). If you add a binder you need to add the same ammounts of alcohol as water used wne bjnding with dextrine. If you add no binder you need about 20% alcohol. Make the bp with this ammount of alcohol into mud like balls. Granulate them on paper lined screens. After half an hour, put the bp back into a bowl, form new balls and again granulate. If it still form worms aait a short time and repeat else you are finished and only let dry. If you want to corn with alcohol, you need the same ammount of alcohol, add the powder to your pump and press pucks with ha d pressure (only light pressure you don't wa t to press oht any alcohol). Now let them dry until the alcohol content is about 6% (a scale helps a lot here). The put the puck back into the pump and press like normal. Brake the pucks up after 1-2 hours.
MadMat Posted January 3, 2016 Posted January 3, 2016 How much Dextrin is needed for example 100g BP? D does not dilute to the alcohol, i wonder whats the purpose to use alc? When alcohol is added to water it inhibits the KNO3 from dissolving.
schroedinger Posted January 4, 2016 Posted January 4, 2016 Mad thats not really right. The main purpose of alcohol is to reduce the surface tension, allowing for better penetration. To effectivly inhibit the dissolvimg of kno3 you need quite big ammounts of alcohol.
Seymour Posted January 10, 2016 Posted January 10, 2016 (edited) While there is reasonable theory behind the desire to use alcohol to reduce the solubility of KNO3, it will also reduce the solubility of the binder. Personally I've always used 100% water, with a few exceptions for experimentation, and in the couple of thousand kilos of BP I've made I have never wished I took any steps to reduce crystallisation beyond simply not adding too much water, and not letting it sit damp for too many days. However each to their own. I've always used a Ball mill, and reactive charcoal, and perhaps I can get away with it while for other people it is more important to keep KNO3 particle size absolutely minimal? And while I also don't use alcohol to reduce surface tension (or at least not regularly) it is good for this, especially for things that are high in charcoal, or sulfur, or oil coated bright flake Al, or other things that seem to resist becoming intimate with water. In my experience, VERY LITTLE is required. I'd start with 2% Alcohol in the water, or even just a few drops on the composition, and working up to a maximum of 5%. Anything over this is just a waste of alcohol and if taken it as far as many people do, it will reduce the power of binders. I consider all common over the counter alcohols to be good for this, IPA, Methylated Ethanol, Vodka... you get the idea. Similarly short chain Ketones such as Acetone and MEK work well too. Edited January 10, 2016 by Seymour
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