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#1 paddy

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Posted 25 January 2014 - 09:08 PM

exactly what is bp slurry,and why and how would you use it. i have been reading but so far hav'nt seen much on timed fuses..please refer me to some good reads on slow burn fuse, i would like to make it myself if possible..thanks pat



#2 pyrokid

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Posted 25 January 2014 - 09:34 PM

BP slurry is a mix of black powder and water, usually with a small percentage of binder added. I use between 2% and 5% dextrin.

 

BP slurries are used to prime fuses and make black match and other things.

 

 

Slow burn fuse is hard to make. Some guys have built visco machines but that is a pretty involved project. You have the option to make spollets, which are paper tubes with compressed black powder, for your shells. Most guys just buy Chinese time fuse.



#3 LambentPyro

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Posted 25 January 2014 - 09:36 PM

In short, BP slurry is used for priming, and for making Blackmatch. I prime my time fuse with it and make Blackmatch with it. However, for Blackmatch, a good binder such as CMC (I sell it for $7.60/lb.), or SGRS. People use Dextrin, it's adequate, but for high aqueous binding, SGRS is used, but CMC is more preferred for Blackmatch.

Edited by LambentPyro, 25 January 2014 - 09:36 PM.

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#4 Mumbles

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Posted 25 January 2014 - 09:45 PM

Generally speaking, BP slurry is a slurry of black powder generally in water with some sort of water activated binders.  Occasionally it is made using red gum and alcohol or with nitrocellulose lacquer for a few specialized applications. 

 

The water based slurry is used for a few different applications.  Most often it's kneeded into string to make black match.  It can also be applied to stars as a prime in something called the toro method.  The slurry can also be used as a glue, particularly for securing blackmatch or other kinds of fuse into holes or nozzles.  It's often used as kind of a combination of glue and prime with comets.  It is painted on the ends or the sides of the comets, and then dipped into granular BP to provide a basically fool-proof prime.  This is also regularly done as part of the priming process of the taking fire end of spolettes and sometimes other delay fuses. 

 

The other application is as a delay in a specialized salute insert called bera or beraq.  The slurry is make stiffer, probably more of a paste, and smeared into a hole in the side of the insert before being primed with granulated BP.  A combination of the slurry composition, the hole size, and wall thickness determine the delay time.  The masters of this technique can manipulate all 3 together to generate 10 or more relatively evenly timed delays. 

 

What would you define as a slow burn fuse?  Anything that burns slower than BP (~3sec/inch) isn't used all that often, or at least made very often.  There is a formula called glusatz that is used sometimes, and burns about 30sec/inch. 

 

 

[edit] looks like some guys got to this before I did.


Edited by Mumbles, 25 January 2014 - 09:47 PM.

Just so you guys quit asking, here is the link to the old forum. http://www.xsorbit2....forum/index.cgi

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#5 nater

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Posted 25 January 2014 - 11:43 PM

I use a slurry made with BP and water or BP and NC lacquer as a priming means pretty much how Mumbles describes above. It works well to prime spolettes and comets.

For homemade fuse, try ramming spolettes. I find them easier to work with for most applications than Chinese time fuse and they spit a much bigger flame into your burst.
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#6 ddewees

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Posted 01 February 2014 - 07:55 PM

How do you use nitrocellulose?

I have some I mixed with acetone, and now has the consistency of thick syrup. Do I mix this with bp (for priming things), or apply the bp after the fuse is dipped?

#7 bob

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Posted 01 February 2014 - 09:22 PM

You have to add black powder to the NC lacquer just like you do when using water or alcohol.
It would be a good idea to dunk it in strate bp after the NC/BP just to unsure ignition, I believe a few people aready mentioned this for the water type but I wanted to make sure you knew that it was the same with the NC lacquer slurry.
Hope this helps.
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Edited by bob, 01 February 2014 - 09:23 PM.

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#8 ddewees

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Posted 01 February 2014 - 09:34 PM

Ok thanks.

#9 pyrogeorge

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Posted 02 February 2014 - 10:10 AM

BP slurry in my comets. ;)

http://www.amateurpy...2489-c6-comets/

 



#10 Shadowcat1969

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Posted 05 February 2014 - 01:39 PM

I have some I mixed with acetone, and now has the consistency of thick syrup. Do I mix this with bp (for priming things), or apply the bp after the fuse is dipped?

 

If your NC lacquer has thickened you can thin it again with more acetone, if you need/want a thinner product.

 

As for priming, you want to actually mix BP into the lacquer before applying it to the surface of what you want to prime. NC by itself is actually a form of paint, and can dry and form a layer that won't allow fire to penetrate it easily. This can cause outer layers of priming materials (like additional BP meal) to burn off without igniting the surface of what you want to burn.



#11 Peret

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Posted 05 February 2014 - 11:23 PM

I set aside a couple of spoonfuls of mill dust when I make BP, and use it for priming fuses with NC. I make my NC lacquer fairly runny and mix the priming slurry about 50:50, which means after the acetone has evaporated it's 95% BP. I just dip the end of the time fuse and never had it fail to light. The slurry only has about 5 minutes working life before it gets too stiff.



#12 fredjr

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Posted 06 February 2014 - 07:46 AM

I use an emptied white glue bottle for my NC/BP slurry. Keeps it from drying out so quick. When it does get a little thick just add some acetone.



#13 yvariro

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Posted 18 February 2014 - 02:37 PM

Hello all,

I'm making a timed insert shell,and i would know if I can prime the fuse with a thin layer of meal powder slurry and then dipped in granulated BP ?
The problem is I'm running out of black match, I don't have the time to make it yet,and it seems that you guys always use double strand b-m tied to the time fuse for priming the report.
Did you ever tried this ?
The slurry method can affect the timing ? Even if it's thin and well done ? Does it has less chances to ignite than the black match method ?

Any help would be nice :)


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#14 Peret

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Posted 18 February 2014 - 04:09 PM

I use BP slurry dip, made with mill dust as I described above, to prime timed reports. I just dip the freshly cut time fuse once, I don't dip again in granulated BP. It always ignites and doesn't affect the delay. I don't prime the inside end. Your mileage may vary, depending on how fat is the time fuse core and how hot your powder and flash, but it works fine for me.



#15 yvariro

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Posted 19 February 2014 - 06:04 AM

Thanks you for your answer,I will definitely  try that ! 


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#16 Vegasnative83

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Posted 18 March 2016 - 03:52 PM

New guy here, thank you. I needed some ratios of how much NC lacquer to use with BP meal for priming. Do any of you make your own NC lacquer from solids, or do you use premade lacquer? If you make your own, how much solid and acetone do you use? If you use premade, where are you getting it from?



#17 lloyd

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Posted 18 March 2016 - 04:48 PM

For priming slurry, you can make or buy without penalty.  If you buy, DO get "nitrocellulose lacquer", NOT store-bought painting lacquer.  Skylighter and others carry it.  Painting lacquer contains so many other plastic substances besides NC, that it's not a terribly flammable binder.

 

About 10% vol/weight of a 10% NC lacquer is sufficient to properly bind slurries.  But for most items, water-mixed BP slurries with dextrin as the binder work fine, and are a LOT easier to handle if you're priming stars.  Fuses go quickly, stars take some time, and the 'open time' with a water-mixed slurry will benefit you in that endeavor.

 

One major error that occurs with fuse priming (and which causes dud shells) is not making certain that the slurry actually touches the powder core of the fuse.  Don't ever just "dip" the fuse.  Often, a bubble can (and does) form over the dead-center, preventing the slurry from actually touching the core powder.

 

Instead, put a shallow layer of the slurry in a plastic basin (like the lid from a coffee can), and TAP the fuse down flush onto the plastic surface through the slurry, then withdraw it slowly enough to ensure the material builds up a little on the end of the fuse.

 

Lloyd


Edited by lloyd, 18 March 2016 - 04:49 PM.

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#18 OldMarine

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Posted 18 March 2016 - 04:54 PM

Oops. Mis-post

Edited by OldMarine, 18 March 2016 - 04:57 PM.

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#19 DaMounty

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Posted 19 March 2016 - 11:52 AM

What if your NCL is made from commercial double base and acetone. Would you still add BP to make a slurry?

 

DaM



#20 lloyd

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Posted 19 March 2016 - 12:00 PM

Absolutely, DaM!  Make your lacquer for "general use" from 10% w/v commercial powder and acetone (10g powder to 100ml acetone).  Yes... that does NOT turn out to be a 10% solution... w/v measures are often used in pyro and pharmaceuticals.

 

The _only_ NC lacquer we used in the factory was made from Green Dot and acetone.  If you follow my instructions elsewhere on making it, you can have good, smooth lacquer in an hour, rather than the 'days' some makers suggest is necessary).

 

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Edited by lloyd, 19 March 2016 - 12:00 PM.

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