FlaMtnBkr Posted February 6, 2012 Posted February 6, 2012 I just got a couple pounds of NC and it smells like it is packed in isopropyl alcohol. The first thing I did was dry a small amount and see how it burned, which it didn't do very well. I need to make sure its dry and try again. Second thing I did was take a ph test strip and touch the still wet NC. I don't know if the alcohol will effect it but it appears to have a ph around 5.5 Assuming it burns good enough when dry to mess with, can I try to further neutralize it with household ammonia? I have read urea works good but ammonia is easier to put my hands on. I would wash with deionized water as a final step. The NC looks like paper pulp and is still really white and I only smell alcohol at this point. Does anyone have any suggestions? I have used smokeless powder for NCL to this point but wanted to try the real thing since I got it for quite a bit less than a pound of smokeless (and I might know why now). I had planned on drying it out and dumping into a gallon of acetone to make a concentrated NCL, and thin it for different uses. Now I'm wondering if I will just ruin a gallon of acetone. What would happen if I did dump it into the acetone but hadn't checked the ph first? Will it just break down quicker? Thanks for any and all help with this.
Mumbles Posted February 6, 2012 Posted February 6, 2012 Ammonia is considered to be harmful to nitrocellulose. I never really took the time to read why because sodium bicarbonate is much cheaper and easier to acquire for me. If you want to neutralize it, I'd soak the NC lint in sodium bicarbonate over night or for a day or so. Give it a squeeze every now and then to allow fresh base into the fibers. The urea thing is more of a stabilizer, though it does clean the NC up somewhat. Give your cotton a good washing with water afterwards, and hopefully it will be much better. If you're worried about sodium contamination, you may need to hunt down some potassium bicarbonate or something. Starting with an acidic pH would probably just make your lacquer decompose faster. It's hard to tell as I don't have much first hand experience. All the NC lacquer I've ever made was from smokeless powder, or from good clean NC lint. Watch out for it (the solids or solution) turning noticeably yellow or red, and having an odor similar to bleach or car exhaust.
FlaMtnBkr Posted February 6, 2012 Author Posted February 6, 2012 Ammonia is considered to be harmful to nitrocellulose. I never really took the time to read why because sodium bicarbonate is much cheaper and easier to acquire for me. If you want to neutralize it, I'd soak the NC lint in sodium bicarbonate over night or for a day or so. Give it a squeeze every now and then to allow fresh base into the fibers. The urea thing is more of a stabilizer, though it does clean the NC up somewhat. Give your cotton a good washing with water afterwards, and hopefully it will be much better. If you're worried about sodium contamination, you may need to hunt down some potassium bicarbonate or something. Starting with an acidic pH would probably just make your lacquer decompose faster. It's hard to tell as I don't have much first hand experience. All the NC lacquer I've ever made was from smokeless powder, or from good clean NC lint. Watch out for it (the solids or solution) turning noticeably yellow or red, and having an odor similar to bleach or car exhaust. Thanks for the reply. Is there a good pure source for urea? I imagine it is just a component in most fertilizer. I thought it was you that mentioned its use though I could be wrong. I would like to neutralize it but stabilizing it sounds good too since I'm sure it will last me a long time. I would also like to avoid sodium contamination if possible since I am planning on experimenting binding color star formulas with it. Although there is a good chance baking soda has already been used. Is there another suitable base that can be used? I have just about all the modern pyro chems on hand. Thanks again!
FlaMtnBkr Posted February 7, 2012 Author Posted February 7, 2012 (edited) Maybe someone will have some input on these questions. If I decide to neutralize do I need to dry the alcohol off first or can I just dilute it with water? Is it best to let it dry naturally or can it be dried in a low temp toaster oven? I don't want to speed up deterioration, but it takes longer to dry than I thought. Since I have a few pounds of the stuff, which is supposed to be hard to wash, can I put it in a large jar with a base and leave it to soak for a couple weeks? I can shake it a couple times a day and stir occasionally to break up the NC. Just want to make sure an extended base bath won't hurt it. When I put some in a solution of sodium bicarb it didn't immediately bubble, but after a couple hours had a few bubbles on the surface. It has been a dozen years since college chemistry so I don't remember if acidity is related to molar concentration? I'm hoping that means there isn't much acid in it and the low ph is more related to the type of acid used. I still like the idea of urea to stabilize. If anyone can point me towards a product that will work well that would be great. I'm worried urea fertilizer will have a lot of stuff besides the urea. And the last thing I can think of, would the NC last longer if slightly acidic, being wet with alcohol or being dissolved in acetone? Thanks for any further input! Edited February 7, 2012 by FlaMtnBkr
warthog Posted February 7, 2012 Posted February 7, 2012 I store mine moist with the alcohol and in the freezer. I check it now and then to see if my frost free freezer has removed the alcohol even from the sealed bag. Once the original seal is opened, I keep it in one of those zip lock bags you can such the air out of with a hand pump but those aren't perfect either, just pretty darn good IMO.
Mumbles Posted February 7, 2012 Posted February 7, 2012 I've always used the fertilizer grade urea. It was sold in a couple pound bag at my local garden center. It's a little dirty looking. I think I just dissolved it to make about a 5% solution, and let any sediment settle before pouring off the liquid. If you want it to be ultra clean, you could probably recrystallize it. I always made about a quart of NC lacquer as needed. I never used all that much. Occasional priming, and some DE. I stored the lint wet with isopropanol in a plastic bag inside of a HDPE container which was taped shut. It originally came wet with water, but I dried it out and replaced that. It should be noted that poor quality NC CANNOT be wet with alcohol. I can't recall the cutoff, but low nitration level NC will dissolve/gel with alcohol. To clean it up, you might want to evaporate the liquid, depending on how much alcohol is in there. Spreading it out on paper and stirring every so often seems to help. I've dried small quantities under a desk lamp. It gives a little heat to help it along. Even with this, it will take several days, at least with water. I don't like to admit it, but I've dried a few grams in the oven as well. I really can't recommend that, and it's a very dumb idea with large amounts, or a gas oven. Combining alcohol in with that is just asking for an accident. If you decide you need to dry it, let it sit out for a while, possibly the better part of a week. If you have a toaster oven or something that can be placed in a remote area, I guess it could be worse. I'd want to make sure to I neutralized, or at least gave it a good base washing before adding any urea. If you want to avoid any sodium, I'd look into potassium bicarbonate. This is about as cheap as I've seen it: http://nuts.com/cookingbaking/leavenerthickener/potassium-bicarbonate.html?
Nitrato Posted February 9, 2012 Posted February 9, 2012 Most of the unstability of NC can be caused by acidic traces in NC that acts as catalysts (like HNO3, HNO2, etc) to self decomposition. Urea reacts with HNO2 to give N2 and CO2 and this is a great help as stabilizer (unless the NC is made to be a granulated powder as propellant, since pockets of gases in those grains can greatly affect burn rates). Is not rare to find quite pure fertilizer grade urea, although this is changing already.. Some OTC urea brands are quite pure and you could do even some fun synthesis with it (e.g. hydrazine sulfate, which is a synthesis very sensible to impurities, any trace of transition metal could screw up your yields). At 45°C urea solubility in water is 165g/100mL whereas solubility in ethanol is much lower 9g/100mL ( http://www.springerlink.com/content/q424686319734h36/ ) , so you can dissolve your impure urea in hot (not boiling! Try to keep below 60°C and that's just fine) water, then filter through coffee filter paper to remove insoluble matter (try to use a cotton ball stuck (not very hard packed) in the funnel, to grab fines that may pass through filter. Its also a good idea, prior to filter urea solution, run a small amount of hot distilated water through filter, this will make filter grab to better to funnel and avoid urea crystalizing in (initially) dry paper pores when you pour your solution (if solution is highly concentrated). Then while stirring, dump in a good amount (e.g. twice of the solution volume) of very cold ethanol in the filtered clean solution, continue to chill and filter urea. You could repeat this process for improved purity if you wish. Due to considerable solubility of urea even in cold water-alcohol mix, you will loose quite a bit of it.. Isopropyl alcohol is still less polar than both methanol and ethanol, so probably the urea solubility in it is still lower than those alcohols, making it a interesting substitute; although making a very quick search I didnt find any table/data relating to IPA/urea solubility and dont know if strange things could happen (like forming two phases), since I didnt tried with this alcohol. Some people like to use amyl acetate (banana oil is pure isoamyl acetate or it can be a mix of isoamyl and amyl acetates) to dissolve NC. Amyl alcohol was used as NC stabilizer in france (until begginings of 19's (1910, IIRC), then discontinued; some years before some warships exploded due to stored NC with amyl alcohol). Is there any chance that some amyl acetate (containing dissolved NC) may degradate over time to give some amyl alcohol(good side) and acetic acid (bad side) in storage? Well.. That may not be the case,since people actually claim its a very stable lacquer. Other know stabilizer are naphthalene and nitro-naphtalenes, although I dont know if they may be useful (or detrimental) in pyro and I didnt find anything about that.
Recommended Posts