7F?

[No Powder]

Just got back from a trip to Colorago and ran into a couple of black powder shooters. They were talking about 7F (never heard of it) and they use it to prime their flinters claim it is a lot hotter and will set of Pyrodex. I just use GOEX but thought this was interesting and wondered if it was true. Now they might have been pulling the guy they were talking to leg as I did not enter into the conversation but was listening on tne side.

 

[misher]

Black Powder dust!!

 

[David W.]

7F used to be made, but I forget by whom. It is more or less dust and only good for target shooters as it will get damp real fast in a hunting situation. You can make your own by taking two sheets of wax paper and rolling over any granulation powder with a rolling pin.

 

[rafterob]

Goex still makes 7f classified as pyrotechnics powder. They (powder inc) would not sell it to our club without mfg. license for pyrotechnics. I have run in to a few who have some, usually picked up at friendship in the past but no one has seen any lately. Perhaps regulations changed.

 

[roundball]

http://goexpowder.com/product-commercial.html

 

[paulvallandigham]

7Fg powder was made for both fire crackers( check legality in your state) and, more than 140 years ago, for the FLASH tray used by photographers to take tintype pictures.

It burns very fast, and very HOT. Whether it will set off substitute powders reliably is something I can't tell you. I have never seen it used for that purpose.

If you screen your powders, you will get a lot of " Fines ", ie. very small particles of powder , or " dust". I suppose of you got a small enough grid screen wire, you could create some 7Fg. I don't know what size screen would be needed, however. I have the screen sizes for Fg,FFg,FFFg,and FFFg powder in an old loading manual.

Graf& Sons used to sell a tumbler with various size screens to clean and sort your powder for more consistent burning, and lower SDV. They may still have it. I just didn't see it on their website catalog the last time I looked. I suspect that they could be a source of information as to what size screen you need to create 7Fg powder. Or Contact Goex, directly. We are Talking Very Fine Dust, here.

And, from personal experience,( burning up the dust residue after screening both 3Fg and 4Fg as priming powder) I can assure you that the prime catches faster, and burns faster with the finer powder. However, it also seems to take on moisture from the air faster, so I don't believe that all the granules still are coated completely with graphite. That makes this a more dangerous powder to be handling. I also believe that part of the "dust" is graphite, chipped off the granules as the powder is run over a screen, or just from being handled in its container. When You use the "fines" for priming, you get much more powder residue on the pan, than if 4Fg is used. Noticeably so. :surrender: :thumbsup:

 

[token tory]

for the FLASH tray used by photographers

I think you'll find you are confusing magicians stage effect "flashpowder" with the stuff photographers used in those devices, a co-incidence of names only.

Photographer's "flashpowder" is a separate chemical entirely, specifically designed to NOT explode, no matter what. :nono:

Mainly it is made up of magnesium powder & a strong oxidizer like Pot Dicromate. It should contain no "gunpowder" at all being designed to mainly make as much of a non-explosive burst of light as was possible with the chemistry knowledge at the time..

 

[stubshaft]

Many moons ago there was a product called "Foxfire" that was supposed to be the best thing since sliced bread for priming rocklocks and putting in the nipple of of a percussion gun. IIRC - they had problems with it exploding, and was taken off of the market.

 

[No Powder]

Thanks all now I know.

 

[Many Klatch]

I had a pound of 7F once. I used it for a while, but got tired of it getting damp on a hot muggy day. I gave it away a long time ago. I see 7F for sale every once in a while but have never seen the need to use it.

Many Klatch

 

[Dave Rosenthal]

Now HOLD STILL while I draaaaaaaaag the shuttttttter a litttle whilllllle longggggggggger!

That's it, the perfect family group photo! Ma and Pa Kettle, with the Kettle Kidlets! :haha: .

High speed "film" had an ASA of 8 or 12 back then! Oh well, I'm showing my age again :haha: .

Remember to put the lens cap back on after the big flash, and before the people MOVE!

Dave

 

[paulvallandigham]

I am sure that you are correct as to what was used in the late 19th century, but I have examined Photographic equipment in museums, and seen these flash sticks? use in period costume demonstrations, and I can assure you that earlier, actually fine Black powder was used. A lot of studios were set on fire because of low ceilings, in the old west, destroying all the photog's props, and his equipment. The powder does NOT explode when lit. Instead it burns very quickly giving off a lot of light. The Magnesium compounds were used later as they were safer to handle, and actually produced more light. The Electric light bulb put an end to all this, in the late 1870s, as it eliminated all the safety issues in taking pictures indoors.

 

[token tory]

Flash trays I assume?
A kind of long, thin trough with a handle extending downwards with a flint & steel type striker mechanism at the center of the tray.

The photographers flash powder was renowned for allowing one shot only as the thick cloud of white smoke & the resulting snowstorm of fine, white powder on all involved meant that the whole area needed to be cleaned before attempting a second image.

It was possible to obtain "flashpowder" from firms in the U.K. (Notably "Johnson's of Hendon") right up through the late 1960's. I know as I ordered 1Lb. cans of the stuff at that time. It was still in commercial use up to that date as the bulbs & electronic flash units of the time were incapable of illuminating large areas such as concert halls.

The light bulb was NOT the item responsible for displacing the flash tray BTW, that was the Gas Mantle, or "LimeLight", the electric light bulb came much later after Edison's patent was commercially manufactured.

Film was indeed slower back then but much more so than you'd think. Many of the colloid or wet plate emulsions were sub ASA, as in about 0.3 asa, had the asa system been invented yet. They were also "colorblind" or Orthochromatic (seeing only blue or "actinic" light) which is another reason for the metallic particles used in flashpowder it produced a light much more intense in the "actinic" frequencies.

You are correct in the comments about studios being burnt down, but this happened because the still burning metallic particles (frequently magnesium) were prone to starting soft furnishings, such as heavy curtains (very popular at the time)burning as the flash ball of light expanded everywhere.

With respect you should verify your information a bit more before quoting dubious sources IMHO.

 

[CoyoteJoe]

What pyrotechnisists call "flash powder" today is generally a 70/30 mix of potassium perchlorate and aluminium powder and it most certainly does explode. Small quantities just flash in an open unconfined tray but in larger quantities it becomes "self-confining" and detonates very violently. It is the "crack" in firecrackers and the "boom" in large aerial salutes. Federal law limits firecrackers to a maximum of .05 grams of flash powder, which would be about 0.8 grains so you can imagine how loud a 16 gram salute can be. Blackpowder gives a redish orange flash whereas the flash powder gives a much brighter white flash.

Below is from Wikipedia.

Flash powder is a pyrotechnic composition, a mixture of oxidizer and metallic fuel, which burns quickly and if confined produces a loud report. It is widely used in theatrical pyrotechnics and fireworks (namely salutes, e.g., cherry bombs, M-80s, and firecrackers), and was once used for flashes in photography.

Different varieties of flash powder are made from different compositions; most common are Potassium Perchlorate and Aluminum powder. Sometimes, Sulfur is included in the mixture to increase the sensitivity. Early formulations used Potassium Permanganate instead of Potassium Perchlorate.

Flash powder compositions are also used in military pyrotechnics, when production of large amount of noise, light, or infrared radiation is required; e.g. missile decoy flares and stun grenades.

 

[necchi]

Now HOLD STILL while I draaaaaaaaag the shuttttttter a litttle whilllllle longggggggggger!

Gotta chuckle bout' that.

I've studied my geneology and have been fortunate enough to find photo's back to the late 19th century. (a great-great uncle was a studio photographer)
Even into the 1940-50's those folks could pose! Trained at an early age.
It's almost as if someone would say "Camra", and they'd gather in a group and freeze. They'er nice photo's. They didn't care for "captured in the moment" that's popular today.
It's fun sharing copies with 20 somethings now, "Oh by the way, that's your great great great great Grandfather". One branch was in America 1740's.
I digress,,

 

[token tory]

My point was that 7f blackpowder was absolutely not "photographer's flash powder" so we agree.

 

[ohio ramrod]

I won a 1/4 lb of #7 at a shoot several years back. It is ideal for puting under nipples for when people have bad powder, or no powder (dry ball). It also feeds nicely through a push measuring spout on a small priming horn. It does draw moisture rapidly and I keep mine in a plastic jar with a tight lid getting out only what I will use that day.

 

[Joel/Calgary]

I notice that some folks are noting the number of "F"s but not the type of powder pyrotechnic (-A) or propellant (-g). I recall that -A powders are much coarser than the -g powders with the same number of "F"s, but not the specifications. Does anyone have the grain-sizes (or sieves) for the two types?

Thanks,
Joel