Sodium Chlorate --> Potassium Chlorate
Posted 03 February 2004 - 10:45 AM
First, I must stress that I do not think this is a good practice. I understand most members having problems getting colour producing oxidizers, and are turning to potassium chlorate for inspiration. I can accept that – but I also believe most members are doing it too early, before getting to a level of construction that justifies the usage of active and sensitive materials, and before they have mastered work practices adequate for the usage of such material.
Putting that aside, I turn to the discussion of making potassium chlorate. I have examined some of the so called “weed killers” available on the market, and I am surprised that members find it so easy to make potassium chlorate. A lab experiment I conducted myself failed to get “easy” results, and I would be interested in members’ experiences.
The first issue is that all the brands, including the “doff” brand, include other materials in addition to sodium chloride and chlorate. Some include manganese, Sodium or calcium carbonate as free flow agents; Chose chemicals do not easily dissolve and will stay in the solution to create additional chemicals. They are in sufficient quantities to create serious colour disturbances. In addition, solubility is different when there are other materials involved, and is likely that more water then usual is needed to dissolve the sodium chlorate and potassium chloride.
The simple procedure used by many – mixing weed killer and a “lo-salt” while boiling, and then cooling to let the potassium chlorate to descent, revealed in a laboratory analyse about 12% of sodium elements!
It took about six repeated washing to come up with the product that contain less the 3%, and that was in a lab environment.
For red and blues, this material proved reasonably adequate, although colour production was somewhat pale (probably due to sodium contamination). Greens, which are closer to the yellow band, were not very good.
I’ll be interested to hear other experiences from other members of the forum.
Posted 03 February 2004 - 06:26 PM
I presume the reaction is as follows:
NaClO3 + KCl ---> KClO3 + NaCl
So I worked out the correct starting masses would be roughly as follows (taking into account the fact that the weed killer is only 53% sodium chlorate):
75g Potassium Chloride (pure, from a chemical supplier)
These were both dissolved in the smallest possible amount of boiling water. No insoluble matter was observed. The solutions were then mixed and left to cool slowly (so crystals would be large and easy to filter). After 24 hours, a large volume of white crystals of potassium chlorate had precipitated. The temperature was further reduced to 0 degrees centigrade, to push as much KClO3 out of solution as possible. The crystals were then filtered out, and rinsed with freezing water (to remove any NaCl solution on the surface). They were then dissolved in a minimum of boiling water, and cooled again. The precipitate was again washed and redissolved. A total of 4 wash, dissolve, crystallise cycles were used. The final crystals were parallelogram shaped. 60 grams of finished product was collected - about 50% of the predicted yield.
In flame tests, the potassium chlorate gave a mostly lilac coloured flame. It was clear that some sodium was present though. However, it looked like there was only a small amount there, as the purple colour was in no way overridden by the yellow. Going on what you have said, however, I would have to remove this to use it in green and good blue colour comps. According to Wouter's Practical Pyrotechnics page almost all the yellow colour can be removed from a flame by this purification method.
I still have all of the water from the washing and preparation. Somewhere in there, there is another 60g or so of potassium chlorate. An idea I had was to allow this to evaporate off until the potassium chlorate drops out. I could either purify this as well as possible, or use it for burst charges and yellow stars, where sodium contamination would have less of an effect.
Finally, Whilst nitrate compositions can produce some truly awesome effects, which are safer than chlorate colours, and charcoal streamer stars are my favourite effect, I really would like to try to expand what I do and produce my own colours. I know I'm not a master pyrotechnist, but I'm not a complete beginner either. I have owned books on pyrotechnics and read Internet resources for 5 or 6 years, and have been regularly making devices for the past 2 years or thereabouts. I think that my working practices are safe, and that I have had enough experience with nitrate based compositions to move onto colour comps. However, it is my intention to buy "Working Safely with Chlorates" before attempting to mix more than a gram or so of chlorate composition, or use it in a device.
PS: BigG, that last paragraph is not meant to be hostile in any way. I just couldn't really think of a better way to word it. Sorry!
Posted 03 February 2004 - 07:03 PM
I dissolve my reactants in water then cool it to 0*C. I then filter it and wash it plenty of times with cold water. Leave it to dry and my product is fairly pure.
I havent bothered to weigh it but when its burnt, I do get a purple flame and as I am to understand, you need pretty pure Potassium Chlorate to produce a purple flame.
When left in the open I find that vitualy no moisture has been absorbed which further proves that it is of a fairly pure form.
Posted 05 February 2004 - 06:33 PM
Edited by tajmiester, 05 February 2004 - 07:26 PM.
Posted 10 February 2004 - 12:35 PM
1) 5 miles down the road from me
2) Listing Potassium Chlorate as a new product on their website [?5.90 for ?kg]
I am now a man with a plan.....
Edited by RegimentalPyro, 10 February 2004 - 12:35 PM.
Posted 18 February 2004 - 02:26 AM
Posted 18 February 2004 - 06:44 PM
I think some kind of diffusion material is needed to improve efficiency and slightly acidic conditions are best, with 40 or more degrees C temp.
Posted 18 February 2004 - 07:45 PM
Posted 18 February 2004 - 10:27 PM
It's a shame that your HSE won't let you aquire the the stuff you need instead of making you resort to "better" living through chemistry..................
Regards, Stay Green,
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Posted 19 February 2004 - 03:02 AM
Posted 19 February 2004 - 09:50 AM
9V Battery? With the AMP drawn, do you really think a 9V Battery will hold for more then an hour? Even a car battery will not survive the AMP for more then few days, and it is most likely that from one rod you will need about two week of running to get anything.
Ok so I am setting up my small batch of sodium chlorate making machine! It holds about 200ml of solution and has a steel nail and a carbon rod for the cathode and anode. Would it be alright if i just use one 9v battery. Oh yeah I have a vent and this lovely machine will be outside.
Also, how can we give you answers if you supply so little information? What type of steel is the nail? What is the surface area of the Anode? Do you run an open or close cell? Do you have PH and Temp control in place? What is your esstimated efficiency? ETC ETC….
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