7 replies to this topic

[Guido Fawkes]

Does anyone out there know of a good test for black powder?
Years ago my antique dealer dad came home with a funny looking pistol. it had a flint "lock" and a hinged cap over the barrel that drove a ratcheted "gauge". the better the powder the higher the reading I suppose. This is no longer around (sadly probably worth a mint!) I've tried the obvious "racing" but this gives no indication of performance in confinement or gas volumes produced any ideas?

[Arthur Brown]

Basic tests such as burning a trail of powder and timing it carefully can be representative. Otherwise given a suitable laboratory a b0mb calorimeter is the correct instrument to use to measure properties under pressure or constant volume. Whether this would be available now I don't know. It's 30 years since I used one regularly. There are also bits of precision glassware that are graduated for determining the volume of gas produced. However as BP gives a hot gas product and most testers use STP then the test will not replicate real performance.

There are several books on the American market

http://www.pyrodirec...show/Books.html They will supply books abroad at a cost! Whether your country will let them in....

[rocketpro]

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Edited by rocketpro, 06 August 2010 - 10:03 AM.

[Guido Fawkes]

Thanks Fellahs it seems I've come to the right place. What binder should I use for the spollette and what diameter would be mini?I've been working on some "Rhythmic mascleta" and have been having great fun playing with pipe match diameters and loads. I made the black match using corn starch which works beautifully but it is fairly fragile I wondered if good old pva might work and add a little durability anyone tried it? Finally I'm probably about to teach a lot of grannys to suck eggs but if you want to make accurate timings if you record the event with reasonably up to date video camera, most of them will break it down to 32 or 64 frames a second. Thanks again

[Arthur Brown]

Spollettes are usually pressed with 1 - 3% water max and no binder, just meal and pressure. Binders mean solvent means that the comp will have to dry and during drying it will shrink. During shrinking it will likely crack or pull away from the tube both causing it to become unreliable and maybe pass fire too quickly.

[rocketpro]

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Edited by rocketpro, 06 August 2010 - 10:03 AM.

[BrightStar]

Does anyone out there know of a good test for black powder?
Years ago my antique dealer dad came home with a funny looking pistol. it had a flint "lock" and a hinged cap over the barrel that drove a ratcheted "gauge".

I believe this was an 'Eprouvette Pistol':

http://images.google...rouvette pistol

Though only one 'field expedient' way of testing BP, it was clearly effective for the flint-locks of the time.

Beyond the methods already mentioned, to test the effectiveness of any BP as fireworks 'lift powder' you'll likely have to resort to ballistic measurements. Timing the flight of sand-weighted film cans or baseballs is a common starting point. Dan Creagan explores this in some detail:

http://www.creagan.n...coal_tests.html

Edited by BrightStar, 02 May 2010 - 02:34 PM.

[Potassium chlorate]

Such an old pistol would be nice to have.

The best black powder is made the way they describe it in pyroguide:

74.46% KNO₃
13.51% charcoal, preferably alder or willow, but any light wood will most likely do
11.85% sulfur

The KNO₃ should be "industrial dust". If it's not, it should be milled alone for 1 hour.

All three ingredients should then be milled together for at least 3 hours, then +5% of a 25/75 alcohol/water solution should be added. Mill for 15-20 minutes more. Empty the drum/jar. Press the pucks to a density of 1.7 or even 1.8. Let dry in room temperature for 3 weeks in a relatively dry place. After that they should be ready to crush.

You don't need a binder at all if you make it this way and press it to this density.