5 replies to this topic

[www.oliverbrown.co.uk]

Hey guys, just after your opinions really.
I have just bought in a load of 99.8% nitrate to sell at the oliverbrown shop, this seemed a really good idea until I tested the product.
Is there any actual gain from really pure nitrate? all I seem to be doing is cato'ing everything, even 60/30/10 screen mix 3/4" rockets pop on ignition. I did manage to get a 10mm to fly quite well but it seems a bit firery for normal use.
I'd make a guess that 50/40/10 would work but as nitrate and charcoal are about the same price have I actualy gained anything by offering this product?

[Sparky]

Hey guys, just after your opinions really.
I have just bought in a load of 99.8% nitrate to sell at the oliverbrown shop, this seemed a really good idea until I tested the product.
Is there any actual gain from really pure nitrate? all I seem to be doing is cato'ing everything, even 60/30/10 screen mix 3/4" rockets pop on ignition. I did manage to get a 10mm to fly quite well but it seems a bit firery for normal use.
I'd make a guess that 50/40/10 would work but as nitrate and charcoal are about the same price have I actualy gained anything by offering this product?

Hi Alex

I've also had mixed results with 60 30 10. Thinking about it I wonder of one batch I had was higher purity and I actually didn't realise!

After some reading and testing I've settled for 55, 31, 14 and it works really well.

Just out of interest what purity was your usual KNO3?

[Sparky]

I just answered my own question, I can see your KNO3 is 98%. :-)

Now this is where my lack of experience may have caused me problems and I'm sure at some point I've had a batch of 99.8 which was Cato'ing rockets and now I've made up some granulated mix at 55, 31, 14 it seems a bit under powered.

Just personally I'd go for the higher purity and then I know where I stand when making comps.

[Arthur Brown]

When Black Powder was a state-of-the-art military explosive I doubt that they could even measure to three significant figures let alone produce or source nitrate of 99.9% purity.

The Nitre "scraped from cellar walls" would probably have been 50 - 80% the rest being stone dust from the walls. Recrystalisation would have yielded something in the mid 90s%, probably the best work produced 95 - 98%.

[pyrotrev]

In my experience it's worth using for glitter mixes (for consistency) and I guess it would also be good for making timing fuses. You do sometimes need to slightly adjust ratios compared to cheapo grades though.

[megabusa]

When you think that we are only talking about probably 1% or so difference in the KNO3 purity, the percentage difference in the final comp will be less than 1%.

This error can creep in normal measuring & weighing anyway, unless you are using really good scales.

As an example, when I add dextrin to BP, I normally add 2%, but if it was 2.5%, I wouldn't worry about it.

Also, when you mill your BP, you will get some lead contamination. I have calculated this to be a few percent in some cases.

The end result is there will be some impurities in your final comp, so I would not bother with the extra expense for high purity grades. The stuff I use is fertiliser grade.