50AE Posted August 28, 2011 Posted August 28, 2011 (edited) I got the idea of posting this topic, because of the "n" number of newbie telling me he had poor BP and claiming his chemicals were fine enough and finally I persuaded him it was not the case and I was right - he was using a coffee grinder. Most of the newbies don't know what finess must the KNO3 and charcoal have when making BP - I didn't know too in the back times.Many are excited when they mill their coarse fertilizer's grade KNO3 in the coffee grinder for the first time and then they think it's very fine. So I will try to help what finess must be reached. This way you will know quickly how much milling time is required for each (or all) chemical(s). Symptoms of coarse chemicals: Coarse KNO3:-BP leaves dross residue. If it looks like melting, the case is very bad. If only white droplets appear - the smaller they are, the better the BP is. Coarse charcoal:-BP throws orange sparks of burning charcoal. The longer they hang, the bigger they are.Coarse sulfur-I don't have experience on this one, but I suspect molten droplets of burning sulfur. Remember - The perfect black powder must leave NO RESIDUE! Only black/brown stains. It must burn cleanly, leaving a smoke cloud and no sparks. A good test is to put a small amount (1g) on a A4 sheet of printer paper. The BP must not burn through, but leave a somewhat nice pattern. I have played with BP on paper to try a new kind of pyrography btw How to know the proper finess of the chemicals?Feel them - Take some of the chemical and rub it between your fingers - a properly fine KNO3 must feel very soft, like silk.For me, a fine KNO3 between my thumb and index fingers feels much smoother than rubbing the two dry. The same goes for the other chemicals. Charcoal is much faster to milled it will feel very soft the most of the time. Look at their texture - The fine product will have tendency to clump. It will also keep any fingerprints if you try pressing on with your fingers. Move/shake the chemical - If they are fine, they will form clumpig pieces, which will break appart with visible cracks. Coarse chemicals will easily move between and will not make any apparent cracks. Clumping in the ball mill drum - your KNO3 must be dry and have anti caking agents to make this rule acceptable. If it cakes, it is probably milled more than enough. Take a look at this photo. This is a batch of very fine meal powder. It keeps the fingerprints and traces on my hand. It has also the cracks and clumps I was talking about: http://store.picbg.net/thumb/DC/4A/c208a5931a35dc4a.jpg I hope this topic helps the just starting newbies! Regards! Edited August 28, 2011 by 50AE
allrocketspsl Posted August 28, 2011 Posted August 28, 2011 I got the idea of posting this topic, because of the "n" number of newbie telling me he had poor BP and claiming his chemicals were fine enough and finally I persuaded him it was not the case and I was right - he was using a coffee grinder. Most of the newbies don't know what finess must the KNO3 and charcoal have when making BP - I didn't know too in the back times.Many are excited when they mill their coarse fertilizer's grade KNO3 in the coffee grinder for the first time and then they think it's very fine. So I will try to help what finess must be reached. This way you will know quickly how much milling time is required for each (or all) chemical(s). Symptoms of coarse chemicals: Coarse KNO3:-BP leaves dross residue. If it looks like melting, the case is very bad. If only white droplets appear - the smaller they are, the better the BP is. Coarse charcoal:-BP throws orange sparks of burning charcoal. The longer they hang, the bigger they are.Coarse sulfur-I don't have experience on this one, but I suspect molten droplets of burning sulfur. Remember - The perfect black powder must leave NO RESIDUE! Only black/brown stains. It must burn cleanly, leaving a smoke cloud and no sparks. A good test is to put a small amount (1g) on a A4 sheet of printer paper. The BP must not burn through, but leave a somewhat nice pattern. I have played with BP on paper to try a new kind of pyrography btw How to know the proper finess of the chemicals?Feel them - Take some of the chemical and rub it between your fingers - a properly fine KNO3 must feel very soft, like silk.For me, a fine KNO3 between my thumb and index fingers feels much smoother than rubbing the two dry. The same goes for the other chemicals. Charcoal is much faster to milled it will feel very soft the most of the time. Look at their texture - The fine product will have tendency to clump. It will also keep any fingerprints if you try pressing on with your fingers. Move/shake the chemical - If they are fine, they will form clumpig pieces, which will break appart with visible cracks. Coarse chemicals will easily move between and will not make any apparent cracks. Clumping in the ball mill drum - your KNO3 must be dry and have anti caking agents to make this rule acceptable. If it cakes, it is probably milled more than enough. Take a look at this photo. This is a batch of very fine meal powder. It keeps the fingerprints and traces on my hand. It has also the cracks and clumps I was talking about: http://store.picbg.net/thumb/DC/4A/c208a5931a35dc4a.jpg I hope this topic helps the just starting newbies! Regards! nice info mate,I dont own a ball mill and only coffee grind my chems,its ok for my rockets rice hulls for breaks etc but since I dont need lift bp I have no need for a ball mill as yet
nater Posted August 28, 2011 Posted August 28, 2011 (edited) I'll add that I've been milling batches of KNO3 in anticipation of Tri-State. An hour in the mill and it is much finer than I was able to get with a coffee grinder. I haven't tried the milled KNO3 yet, but I suspect the fineness of the KNO3 was to blame for my sluggish rockets. Edited August 28, 2011 by nater
Mumbles Posted August 29, 2011 Posted August 29, 2011 I actually did a screen analysis on coffee ground KNO3. I typically ground my KNO3 to pass a 24 mesh screen before putting it in the ball mill, and to pass a 60 mesh screen before using it in stars. I took some of the 60 mesh stuff which feels a lot like flour and ground it up even more with a coffee grinder to see what it could do. This is much finer than I typically ground anything. I wish I had my results, but they were on a piece of paper in my notebook during my accident and were thrown away most likely. Going off of memory, it was something like the following: From a 40g sample: -60 mesh: 100%-100 mesh: ~60%-200 mesh ~5%-325 mesh: Nominal. There was a little, but it barely registered on a 0.1g scale The stuff I normally used didn't have much passing 200 mesh, and maybe only 30-40% passing 100%. Based on feel, I could barely tell the normal vs. excessively ground up stuff apart. I wouldn't consider anything coarser that -200 mesh "fine enough".
50AE Posted August 29, 2011 Author Posted August 29, 2011 The stuff I normally used didn't have much passing 200 mesh, and maybe only 30-40% passing 100%. Based on feel, I could barely tell the normal vs. excessively ground up stuff apart. Well, I can feel the difference of finess between each hour of KNO3 milling. If some fingers aren't sensitive, then the look and the caking should help.My fertilizer KNO3 starts to clump in very small dots inside the drum when it gets ready.
Recommended Posts