5 replies to this topic

[W.P]

Hello. I am new to this site and I have a question that i need answered. When ever I buy potassium nitrate it normally comes in large quantities (due to its commercial use) but i find that it clumps together. If it is absorbing moisture from the air then wont that mean:

1. Mixing compositions accurately will be effected due to the weight of the water being counted

2. The performance of the composition (with the exception of BP) will be worsened- especially in Mg/KNO3 flash powder + nitrate flash

3. Possibly will it effect the quality of BP?

Just to insure that these don't happen, i normally order small quantities from specialist pyro dealers and create BP with it within the same day of opening the bag.

SO... if the hygroscopicity does effect the performance then is there anyway of storing it in a moisture free environment without going too extreme (silicone based moisture control and all that nonsense)

And sorry again if this was posted before.

Thanks.

[cooperman435]

If I want my kno3 relly dry then I put it in small sealed zip lock bags or put it on a radiator overnight before using it.

Its hydroscopic but will still quite easily give up its moisture if the sourounding air is below the moisture content of the chemical itself so gentle warming will will ensure its completely dry.

[BrightStar]

Hi W.P.

Interesting question... of my last two batches of KNO3 from a well known UK garden supplier, the first was a dry, fine, freely flowing powder; the second coarse and clumpy. I noted much the same BP performance with the two. Where there was a major difference was using raw 'green mix' type comps in fountains (eg Perigrin Iron 1) - the first batch was spectacular, the second hardly worked at all...

I guess that drying and milling would improve things, but the variation is still interesting.

Edited by BrightStar, 13 May 2007 - 05:57 AM.

[W.P]

Well thanks for the advice on warming it to remove the moisture- thats exactly what i wanted to hear. Not any of those crazy put it in a bag, surrounded by silcone moisture control pellets, then inside another case etc.

And the bright star, i expected that it would be horrible for greenmix, so technically wetting it would completely dissolve the KNO3 so it wouldnt matter if it became clumpy anyway?

Also, does hygroscopicity effect the quality of flash powder in my KCLO4?

[BigBang]

I have never had any problems with hygroscopcity with either KNO3 or KCLO4. Yes they do get a bit clumpy, but this happens whether i keep them in airtight containers or not. But either way, i have not noticed any fall in performance.

But as was mentioned, if you are worried about this, just put in a warm place overnight.

[W.P]

Thanks, that was the best thing I've ever heard- the KNO3 in the warm place. It has solved a problem I've had since I started pyrotechnics. I dont know why I didnt think of it . Well thanks again guys, this is a great forum