firetech Posted March 15, 2009 Posted March 15, 2009 I've taken a look at some instructionals on how to make dextrin from corn starch. The process simply involves baking the corn starch at roughly 400 deg (f) and disturbing every 20 min or so. Anyone else tried this before? I'd like to find out if this works before I try it, it seems to be time consuming.
tentacles Posted March 15, 2009 Posted March 15, 2009 It works fine - if you know your oven temps are correct, I suggest 425F, as it will produce better dextrin. If your oven is too hot, though, it will burn the dextrin.
Arthur Posted March 15, 2009 Posted March 15, 2009 It's well worth the time! Cornflour (UK) Cornstarch forms perfect Dextrin when heated. Take a retail pack of cornstarch and simply spread it on a tray and put it in the oven. Stir it occasionally and it's "Done" when it becomes a uniform pale gold colour. Stirring is important as the process proceedes, as any thickness of powder may burn on the surface before the full depth is cooked. If the oven is already in use for cooking then use it at the same time. Make up a whole pack of cornflour into dextrin, and put it in a good bottle, that way you have a ready supply every time the formula says 2g just weigh it out!
firetech Posted March 15, 2009 Author Posted March 15, 2009 Thanks guys, I guess the process really works eh? =]. I'll give it a try probably today or tomorrow. Thanks again.
Miech Posted March 15, 2009 Posted March 15, 2009 Has anyone tried catalyzing the reaction using chlorine (in any form)? I read that factories either use hydrochloric acid or sodium chloride to speed up the process, so I wondered if that would be reproducable at home. I'd go with the NaCl, I don't like HCl fumes that much.
Mumbles Posted March 15, 2009 Posted March 15, 2009 Most of the accounts I've read used an acid catalyst, not chloride, although HCl is the most commonly used one. I found a patent at one point that used boric acid, that seems doable and safe for home. I don't know how well it works though. I'd personally avoid anything having sodium in it for pyro. The small amount in the dextrin could wash out purples or blues potentially.
firetech Posted March 15, 2009 Author Posted March 15, 2009 Hey everyone, I just wanted to let you know I completed my batch of dex..It went well. It might be a bit overcooked but the properties are still the same as that of store bought dextrin.
andyboy Posted March 15, 2009 Posted March 15, 2009 Good for you. It usually takes a while before new pyros try to make chems and stuff for themselves but eventually one finds out that it is so easy (most of the time) and so much cheaper and/or rewarding to make it yourself. This is especially true with dextrin, not so much with hemis though, time-consuming and tedious as it is. And some chems are easier to pay for, but that's another story.
firetech Posted March 16, 2009 Author Posted March 16, 2009 You are very right andyboy. Things like charcoal and dextrin can be made at home with few tools and items and just a little bit of time and labor. I roll a few of my own tubes and any model rocket (including the motor) I have flown has been 100% homemade. I plan on making magnalium in the near future since most prices on it are ridiculous. Magnesium is quite a hard metal to find laying around though...
Arthur Posted March 16, 2009 Posted March 16, 2009 (edited) Magnesium is retail in the UK as sacrificial anodes for some cemtral heating systems -usually ingots the size of a teacup. the only pure aluminium we can get is under street electric cable. Electrical ali is pure any other alloy usually found in scrap will be a mixture and will likely include copper. Edited March 16, 2009 by Arthur
mike_au Posted March 17, 2009 Posted March 17, 2009 Magnesium is retail in the UK as sacrificial anodes for some cemtral heating systems -usually ingots the size of a teacup. You could also check out boating supply stores, again it is used as a sacrificial anode.
derekroolz Posted July 7, 2009 Posted July 7, 2009 Magnesium is retail in the UK as sacrificial anodes for some cemtral heating systems -usually ingots the size of a teacup. the only pure aluminium we can get is under street electric cable. Electrical ali is pure any other alloy usually found in scrap will be a mixture and will likely include copper. Also try a camping shop and they should have magnesium fire sticks(you have to grind down the mg, wich is a lengthy process...)but if you dont have any other acess to Mg, it is a good way!
Swede Posted July 8, 2009 Posted July 8, 2009 (edited) Hey everyone, I just wanted to let you know I completed my batch of dex..It went well. It might be a bit overcooked but the properties are still the same as that of store bought dextrin. And now you have that funky burnt dextrin-cornstarch smell! I have yet to make a batch that does not have "the smell", something that the one commercial dextrin batch I bought does NOT have. No big deal, it still works. The topic of acid catalysis comes up often. I keep thinking I'm going to give it a try, but I've got too much dextrin as it is. Boric acid sounds promising. Probably just about any non-sodium acidic salt might work. Ascorbic? Ground to airfloat and evenly distributed, it might work. I've got a bunch of little ceramic vessels that would be ideal for a test. Can anyone think of mildly acidic salts to try? We've got: - boric- ascorbic- citric- salycilic- sulfamic Edited July 8, 2009 by Swede
Pretty green flame Posted July 8, 2009 Posted July 8, 2009 I doubt this could work in a dry state, if I were to try it, I'd give it a shot with straight boric acid.
Swede Posted July 8, 2009 Posted July 8, 2009 I doubt this could work in a dry state, if I were to try it, I'd give it a shot with straight boric acid. Agreed, if it does work, it would be only from ambient moisture or moisture within the starch or acid salts themselves.
Swede Posted July 8, 2009 Posted July 8, 2009 I've got two experiments going right now. The main experiment is from Frank's reference to acid-catalysis here:http://ljs.academicdirect.org/A07/09_16.htm In this experiment, 2ml concentrated HCl and 1 ml 20% Nitric Acid were diluted in 150 ml distilled water, and added to a spray bottle. A small bowl of corn starch was sprayed with the acid, then mixed. Interstingly, it went from snow white to very pale yellow at room temp. Enough acid water was sprayed until the starch formed curds, like cottage cheese without the fluid. These curds were easily manipulated, and not messy at all. The bowl is currently "aging" per the web site for 24 hours. It will then be roasted at 80 to 100 C until dry, an hour or two. The second experiment is 1% boric acid added to dry corn starch. That one is currently baking at 100 degrees. Wetting it would not have been difficult, but I wanted to try it dry and see what happens. I have hopes for the curd method. It already appears to be transforming. The heat will probably do little more than finish the transformation and drive off residual gasses and moisture. My guess is that adding the dried clumps to a ziploc bag and giving it a few whacks will totally break it up to its natural state.
TYRONEEZEKIEL Posted July 9, 2009 Posted July 9, 2009 Does anyone have the chemical formula for the dextrin we make and use?
derekroolz Posted July 9, 2009 Posted July 9, 2009 Does anyone have the chemical formula for the dextrin we make and use? Well if your talking about the molecular formula it is: C6-H10-05.
Mumbles Posted July 9, 2009 Posted July 9, 2009 Try (C6H12O6)x Theres a range for x by definition of what a dextrin is. I think it's 3-7.
Swede Posted July 9, 2009 Posted July 9, 2009 Results of the dry starch with boric acid - nothing. No conversion, no notable color change. The hopeful bowl with the curds is now baking at 100 degrees C for 1 hour. If this works, I'll then try boric acid with starch, moistened, but the spritzing of the dilute acid was really easy, so if the latter works and makes a superior product, it might be worth pursuing. I also tried the iodine method (tincture, in this case) to test the dextrins that I have, and both homemade and commercial dextrin tested strong positive for starch. AFAIK, the conversion is not 100%, and the starches remaining will turn the test purple, but that doesn't mean it's not usable. Probably a better way is to determine the overall (as a %) solubility of the product. Start with 10 grams, dissolve, filter, weigh the remnants.
Mumbles Posted July 10, 2009 Posted July 10, 2009 You might want to thoroughly dilute the mix. Dextrin has a reaction with starch too. Starch turns purple/black, while dextrin turns red. Even if there is some starch in there, it will be fine.
Swede Posted July 10, 2009 Posted July 10, 2009 Well, the acid-catalyst dextrin was a massive disappointment. The "curds" did not convert at all. I decided to make it into an acid gravy, but that produced rock hard lumps in the end, and portions were charred even at 120 degrees C. Overall, for me at least, I've laid the question to rest. Attempted acid catalysis = total PITA and not worth pursuing. Maybe someone else will have some luck.
derekroolz Posted July 10, 2009 Posted July 10, 2009 Try (C6H12O6)x Theres a range for x by definition of what a dextrin is. I think it's 3-7. Sorry about that, your right.
Mumbles Posted July 11, 2009 Posted July 11, 2009 Have you tried traditional dextrin manufacture temperatures with the acid treated corn starch? I know the patents give these low temperatures, but something just isn't working.
TheEskimo Posted November 20, 2009 Posted November 20, 2009 Sorry to bring up an old topic but....Can dextrin go past an expiration limit? I have some from June or July sitting in a glass jar, with a tight lid. I made some D1, and they are dry, because they burn fast, and glitter the way they are supposed to. I put in the usual 5%. However, they can be crumbled in the hand, and cannot withstand even a decent firing from a star testing gun. Has my dextrin gone bad? I think that I will make some new dextrin tomorrow, just to check.
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