61 replies to this topic

[adamw]

A lot of literature says about the problems of hydroscopicty. They name Dextrin as being a problem but I have never had any adverse effects from using that as a binder.

A 'damp climate' need not affect a chemical or composition as long as it is stored properly anyway. Unless you are going to live in a rain forest I wouldn't be too put off about these comments.

[Phoenix]

Thanks. I probably won't be going to live in a rainforest any time soon, so that should be OK. Have you used Gum Arabic? Did it strike you as being better than dextrin? I probably won't bother with it unless the match is more flexible, since mine tends to flake quite a bit (it is only single cored match, and I have made multi cored match which helped, but it was a bit too thick).

Edited by Phoenix, 03 April 2004 - 03:48 PM.

[adamw]

No, havent use that gum much. I have some match made with it though and I prefer that sort when making Saettines.

[Phoenix]

I mainly wanted a tough, thin match for small bottle rockets and palomas, and other stuff where there isn't room for a thick fuse. I use thin cotton string with a dextrin bound coating of BP, which usually still has a white core, and this is OK as a delay fuse if it isn't bent at all, but it sometimes fails to pass fire if it is bent and the coating flakes off. It's fine for piped match, and I prefer to use this thin sort, as it takes less composition, and in the case of leaders it means the shell OD can be closer to the mortar ID. On my 40mm shells this is particularly advantageous, as if it was much thicker there would have to be a disproportionately large gap between the shell and the mortar to leave room for it.

Incidentally, I used the multi core match I mentioned before for a few seattines, and it worked every time. I've just made about 12m of it, with dextrin, as it is nice and reliable, and the thickness doesn't really matter if I use it for fusing larger things like fountains and 12mm rockets. I'll leave gum Arabic on my "not so urgent" list, along with sodium silicate, and see how it performs when I get some. For now I can use cracker fuse for my smaller things if I feel the need for a high success rate (like when people are watching) - it'll just take a while longer to make.

[paul]

Hello! I only can recommend Gum Arabic as binder for blackmacth. It only has advantages:

it?s cost effective (100g 2.6?); while you only need a solution of 5 parts GA in 40 parts water

blackmacth made with GA are relatively flexibly

the blackpowder does not crumble away (can I say tha this way? )

and last but not least, they dry overnight. dextrine-blackmacth does not drie overnight.

After one day you can cut them in the disired lenghts and dry them a more few hours in a warm place

greets,
paul

Edited by paul, 15 April 2004 - 04:53 PM.

[Phoenix]

Hi paul, thanks you for your advice. Like I said before, I'll get some sometime, but for the time being I'm OK for black match.

PS "the blackpowder does not crumble away" sounds fine

[alany]

I've always liked using gum arabic as a binder for blackmatch, especially the very thin stuff I make for fusing smaller devices. I also tend to add a little paper pulp if I am using only a single thread, not enclosing slurry in 2 or more yarns.

The big disadvantage of gum arabic is that microbes just love the stuff, and a solution of it will spoil in a few days unless you boil it and treat it like agar, or add something to it that is toxic to most life, like copper or chromium salts. A BP/gum slurry is an almost ideal nutrient solution for many bugs, so you need to use it all in one sitting and dry the match quickly.

Priming is the best way to ensure match will carry fire through narrow holes. Before I started using meal/NC paste to prime pretty much everything I had lots of fuse failures. Now they are pretty rare. At worst you can use BP/water slurry, but I recommend meal/NC slurry using acetone, it dries much faster and burns very fast, with no loss of speed from nitrate recrystalisation.

[paul]

Hello Alany! My GA solution is over one year old, but nothing happenned to it over the time. Some of the ga settled on the ground of the glass but when I shake it a few times, its a perfect yellowish clear solution again! I did not used hot water for the solution. Just clear and cold tap water...

For priming you can use schellack/alcohol with blackpowder, too. No recrystalisation of the potassium nitrate and hardens quickly.

But I prefer NC-Paste/Meal too, cause it sticks very well to must surfaces.

[alany]

I have a small bottle of gum arabic solution, that I currently use as an end-stop for my ball mill (it just happens to be the right size and weight). It was a light yellow for a week or so, but then turned cloudy and grew a grey crust on the surface of the solution that eventually sank. I am too afraid to open it for fear of exactly what I've cultured.

Then again, I have another larger bottle that I keep in a dark cupboard that hasn't changed visually in about a year, but smells terriable when you open it. It is a much weaker solution.

Now days I just make up a solution as required. The shaking required is a bit tedious, it seems no matter how slowly I add the gum arabic and stir I get bits that are hard to dissolve without shaking for several minutes which gives me a froth that takes a week to settle completely.

I find meal/shellac burns too slow, in fact when trying shellac to water proof chinese fuse it made it almost unignitable if the core became soaked. Red gum seems better, but NC burns quickly on its own and isn't just extra fuel so I prefer it. As you say NC lacquer bound meal is very sticky, it is virtually impossible to get off paper or out of clothing! Even my slick laminex work bench has to be scraped clean of it.

[Phoenix]

I tried that spray painting black match (with silver paint) idea that I described a while ago, and it seems to work. So far I've just done a few centimetres. They burned much slower, but pretty fiercly, with flashes at the burning end where the aluminium was igniting, though no aluminium sparks in the flame. Furthermore, the match was much stiffer. When bent the paint cracks, but no powder flakes off. The fuse will burn through a pressed clay plug. I havent tried this, but I guess it is water resistant too. Last, but by no means least, it is indeed shiny and silver!

I have made a 7 shot cake with length of this fusing the tubes, and it includes two of the insert shells that Matt and BurlHorse described (thin walls, tied closed around the blackmatch fuse). These would not work with raw match (muzzle broke) but I will see how the inserts and the cake as a whole function tonight (conditions permitting). Check here for an edit if you're interested.


[EDIT] Bugger. The cake just sicked all seven shots out in about 1.5 seconds. I think that the fuse was igniting where it had cracked at the bends (it was a round cake). The inserts no longer suffered from the muzzle break problem, which is good, bun instead came down and broke on the ground, which is bad.

I'll try making a square cake or a Chinese candle with the painted fuse next weekend, as this will avoid bending it. I will also cut the fuses on the inserts shorter, as they had about 7.5mm of extra fuse behind them, and the painted fuse does not ignite from the sides.

BTW, just realised where my original post about his idea was; in this black match topic

Edited by Phoenix, 25 April 2004 - 08:51 PM.

[Chaz]

Heres a video of my Blackmatch burning:

Poor Quality Blackmatch

You can see the pearls running over the fuse. Its unreliable, last night I was dissapointed by it because it failed to ignite my experimental Polumna Rocket.

At least I've got some visco on its way, 2-4 weeks delivery time remaining.

[alany]

Heres a video of my Blackmatch burning:

Poor Quality Blackmatch

That's not *too* bad, but the core seems to still be white, how do you make it?

You can see the pearls running over the fuse. Its unreliable, last night I was dissapointed by it because it failed to ignite my experimental Polumna Rocket.

Try using several thinner yarns to enclose more powder.

With that Mg/KNO3 flash you shouldn't really need the paloma which is just going to be an aerodynamic problem for the rocket. Just extend the head of the rocket an inch or so with a few turns of kraft, pour in some flash and close the top with a triangle fold or wadding and hot-melt. It should be plenty loud.

At least I've got some visco on its way, 2-4 weeks delivery time remaining.

Oi, give me some! Where did you order it from?

Phoenix: sounds like my first and only attempt at a round cake:

http://www.vk2zay.ne...vice.php?id=136

If you look at the pre-test pic it is kinda obvious why it chain fired, but I haven't tried again since with a better matching design. Matt remains the Aussie king of the cake. I have no idea how he has the patience to construct the large cake devices that he does. Hanging out for his big fanned thing!

[Matt]

I have been meaning to do a write up on my black match fused cakes, need a good GOOD batch of fuse otherwise youll scream. The buggers can take a while to make and to just have it fail.

I have a new fuse jig, its a small plastic container nailed to a board(whoa high-tech) with 5 pins on one side, buy some spools of MACHINE COTTON, remember that, machine cotton. Extremely thin and 5 of em with BP on it can make some ultra reliable fuse.

The big fanned thing has certainly taken its tole on my mind. Only 11 more mortars to go....... then 50 cans ugghhhh.
Completely unrelated I made a 3 break 20mm shell today for the hell of it, anyone for bets on its success? Im worried when one breaks itll throw the other 2 off course.

-Matt

[alany]

I've got a 'crossmatch' making machine which is basically one of my infamous PP jars with three small holes for yarns to go in and one larger hole for all three to come out together. There is a piece of bamboo lower near the bottom going across the path of the threads to direct them through the meal soup. Here is a pic of it doing one thread ages ago, the ultra small match I use for hummers etc:

http://nexus.cable.n...90/p0002991.jpg

As you can see, the match it makes is a coated OK if you pull slowly, but still a little pale at the cut ends. It works OK, but I need a bigger one and I dislike doing it this way, I prefer to let a hank of the cotton sit in the slurry for a little while and really get it soaked into it then dust the match before drying.

I think next time I try a cake I'll use chinese fuse made with meal/NC paste. I basically never use that anymore, and it was very reliable, but time consuming to make.

Just make sure you lift the triple break nice and high, so the bottom shot won't land on your head or something.

[Chaz]

Oi, give me some!  Where did you order it from?

A mate shipped it over. Incase anyone is wondering, we didnt just bundle it in a postal bag and ship it off. We got it properly labelled, with all the appropriate legal info, and shipped it via surface mail. Cant wait for it to arrive! 100 feet of the stuff! The total came to ?16 shipped.

Maybe some time I might start selling it on in the UK, make a bit of money from it (dont worry, I wont charge ?5/meter like some people!), but not yet. I understand how much of a holy grail it is to all us UK pyros!

About my blackmatch. I use meal powder, milled up for about 7 hours. Add dextrin, then add water until its of a yoghurt consistency. Its hard to describe, so maybe I'll get a video of my spooning it around next time I make some. Then I dunk the string in (its the standard string stuff from Sainsbury's) and let it soak for about a minute. Then I just pull it out, and strain it through my fingers (with gloves) to save the excess, and get a more or less consistant thickness.

Hang up to dry, then done.

I've been told that maybe I should try adding more KNO3, because at the moment its overfueled because of the string. I've tried this, I soaked the string in a KNO3 solution, then proceeded as usual. It didnt seem to help.