14 replies to this topic

[wjames]

Just after some clarification here really.

I've Just Discovered that my Bag of Pot. Nitrate is somewhat Damp. I'm not talking wet....Let me explain a little

it get mine at around 30 mesh, and i store it in std. wide neck chemical jars. 1000ML - i filled one up last week, and went to use some this evening....went to pour some out, and it was "caked" a quick shake loosened it up though.

This explains my recent poor BP, and Flash.

Now, my dilema....Drying it.....

I'm all for spreading it out on an old (and clean) baking tray, and whacking it in the oven for a while.....if nothing just to bring it up to 100 degrees.....

Or does someone else have a better suggestion.

Thanks in advance.

[a_bab]

This does not explain in any way your poor BP, but rather your poor ball mill (if you have one). Actually, a bit of humidity makes it faster.

Also, this is normal for pot nitrate: it has this annoying caking behaviour. So drying it won't help, as it'll quickly absorbe just nough moisture to cake back, as it likes

[wjames]

ive got 20g of bp here that i made last week, with my old nitrate....its much faster than bp made with my new nitrate. everything else is the same.

i'm well aware about humid powder being faster.....humid being the key word, not damp. whats the best way to quantify just how damp it is ???

[fruitfulsteve]

weigh out 100g dry it and reweigh it, the difference = amount of water that was in it

[phildunford]

If you have an accurate balance, weigh it, dry it, weigh it again and the difference is pretty much the weight of the water.

In a lab, you could use a dessicator, but I'm sure a very low oven would work. Electric not gas! and a small sample - say 1g. Low temperature - maybe 50 degrees. Apart from the danger of ignition, there is also a danger of decomposing the Potassium Nitrate if the temperature is too high.

Edit - Pah! Steve got there first - lol

Edited by phildunford, 27 October 2009 - 10:32 PM.

[crystal palace fireworks]

Why not use sodium silicate (gel) in a airtight container to dry out your compound?

[Mumbles]

If it is in the crystal structure, dessicants can't dry it.

[crystal palace fireworks]

If it is in the crystal structure, dessicants can't dry it.

Would aerogel be any better?

[Mumbles]

You want to dry with this stuff?

http://en.wikipedia.org/wiki/Aerogel

[crystal palace fireworks]

You want to dry with this stuff?

http://en.wikipedia.org/wiki/Aerogel

I don`t personally! is it not safe, incompatable or ineffective even though silica aerogel is not in dessicant form?.

[Mortartube]

Saltpetre will naturally cake even if you dry it in an oven and put it back in a jar. It is from Greek. The salt bit is obvious and the other part is from Petros meaning Rock.

You just have to grind and sieve it again or roughly sieve it and ball mill it. Are you thinking it is damp simply because it caked or do you have another reason for that conclusion?

[wjames]

i mainly came to that conclusion from the fact it attacks my atomized Mg within an hour or two. My Old batch of Kno3 Was fine for several days.

When i say attack, i mean there is a clear difference when i burn 1g of hour old flash, when compared to freshly produced flash.

[BrightStar]

Dealing with moisture in ingredients is an interesting topic.

I always dry my strontium nitrate before use, even though it's stored with silica gel. I simply weigh out an excess into a ceramic bowl and bake it at 150C. Your KNO3 won't decompose below 400C so in theory you should be OK, though I'd cover the bowl with a cotton cloth if using a fan oven...

I have KNO3 from several sources in my store, ranging from a talk like fine powder to large crystals. They seem to perform much the same in BP given sufficient milling time. Where their performance differs drastically is in screen-mixed fountain comps. Coarse, damp KNO3 in combination with still-sticky coated iron filings produces a very disappointing fountain indeed

I'd be interested to hear how much mass your KNO3 loses on drying...

Edited by BrightStar, 28 October 2009 - 10:36 PM.

[Mumbles]

Are you sure it's damp KNO3, and not impure KNO3? KNO3 can contain bases such as KOH or K2CO3 which would drastically speed up reactions.

[leosedf]

I simply place a large dessicant on the jar.
My dessicants weigh around 500g each and i get them from my work(our equipment has inside them for transport).
I usually dry them at 100C in an oven as the instructions say and can be reused, they are very large and absorve allmost anything on a jar or cabinet.
They come from www.nefab.com