8 replies to this topic

[The Lizard]

Hi everyone,

I am new to the forums but have been making fireworks for a while now.

I have recently tried to make black match using cotton string and black powder mixed about 1/5 with dextrin. I mixed it well, added some methylated spirits to dissolve it and make it into a slurry. I then took a plastic container and drilled a hole through the lid. I put the string in and pull it out through the hole. The string I used had been dipped in potassium nitrate sol. and left to dry over night. I left the black match to dry for about 18 hours. When lit, it simply sparks and occasionally burns about a centimetre down one part of the black match. So only about half of the black match burns on one side of the string. I know this sounds confusing but is a bit hard to explain. It is really weird because when I put it in a pile it seems to burn really well. If anyone could help in any way I would really appreciate it.

Thanks

[pyrotechnist]

Did you bind it with water as well as alcohol? the dextrin needs water to bind properly. Make sure you also have a thick enough layer of BP on the string, I normally use around 95 BP and 5 dextrin and that seems to work perfectly fine for me.

[BrightStar]

Hi, welcome to the forum.

The first and most important variable is your black powder. Good black match needs good BP, particularly if you are hoping to use it as quickmatch or crossmatch later on.

Assuming you've succeeded in making fast BP meal, you'll want to add 5% dextrin - nearer 1/20th than 1/5th. You can experiment with using slightly less dextrin and an auxiliary emulsifier / binder such as CMC (modern wallpaper paste...), PVA or one of various gums. These will give you a less flaky and more flexible match than dextrin alone. Whatever mix you go with, it's still 95% good BP.

As a solvent, use water not meths! You can though use 9/1 water/meths to speed up the drying a bit. More than about 20% meths and you'll prevent the dextrin from binding.

Then comes the choice of string. The key thing is that it has to be fairly thick, soft and absorbent. Strong garden cotton twine is not much good. You need either 'dishcloth cotton' or 'soft crochet cotton' (ask your Mum)... The BP needs to be worked into the fibres well. I tend to 'wash' the string by scrubbing it in a fairly thin 'BP soup' than draw it though an inverted cut off glue bottle full of thicker 'BP slurry' for the outer coating.

Assuming you've got this far and your match is safely hung up on a drying frame outside you're nearly there. It should be fine as is for black match or quick match. For cross-match that has to burn through very tight constraints, I tend to cut it into shorter lengths once dry and dip again in the BP slurry for an extra-thick outer layer.

Enough detail for now... like everything else in fireworks it takes time and practise...


EDIT: Just checked Weingart and he recommends 9% dextrin, I'd consider this an upper limit.

Edited by BrightStar, 14 July 2010 - 01:22 PM.

[Atom Fireworks]

Ive had trouble making black match and put it down to inferior meal. What seems good black powder too you can be really poor to someone else i too think its 95% bp and the rest string and technique.

[The Lizard]

Thanks for you're quick responses

I will try out all of your ideas, Also does anyone know how long I should leave it to dry for?

I have also been recently trying to make a small firecracker sort of charge and made one with granulated bp which worked great, I then tried to make one with compacted bp which kind of went of like a fountain.

Does anyone know how I could make a decent firecracker that went of with a bit more than a mere poof.
thanks,

[PyroSkitz]

Thanks for you're quick responses

I will try out all of your ideas, Also does anyone know how long I should leave it to dry for?

I have also been recently trying to make a small firecracker sort of charge and made one with granulated bp which worked great, I then tried to make one with compacted bp which kind of went of like a fountain.

Does anyone know how I could make a decent firecracker that went of with a bit more than a mere poof.
thanks,

Ok just quickly for black match, cotton string is easily to get, comes in a ball of yarn style, not usually on a spool unless a very long piece is needed, I make some kno3 solution, get cold water, try it to be very cold tap water, keep adding kno3 and mixing vigourously untill no more kno3 dissolves and then add your string, I've made a big nail board, 2 meters length, got 17 nails in each end for winding the string around for easy black match making, I have a little pot used for storing like carrot sticks or something like that, put a hole in each side, the a hole on each side adjacent to the holes but also lower down, where a pencil will be situated...make a tomato soup/ yogurt thick bp slurry 5% max dextrin IMHO, pull the string in one hole, place it under the pencil and then out the other hole, then just pour in your slurry, I just pull the pot around the string and make sure it's all coated, will try make a video soon I can test it and it works in 3 hours or so depending where you store it.

On a note for firecrackers, you need a decent sized tube, granulated BP around -6 mesh, no dust seems to work fairly decently but depending on the size of your tube 6-12 mesh could also work, you can't fill it all the way, as you need a void for the gasses to build up, test 1/3 full or 1/2 full see what gives the best report for you, if it's the same ID as a straw then you can hot glue the ends close, otherwise 4/5 layers of kraft tape seems to do the job alright, I do the same thing but only fill my tubes 1/6th full for obvious reasons haha

I hope you found my information useful, it was quite hard typing all that out on iPad haha
Thanks
George

[Mumbles]

I never had much luck simply dragging it through slurry. It simply coated the outside in that case, and flaked off rather easily. I much prefer to roll into a coil, and kneed into a warm solution of BP slurry. As it cools, the slurry solidifies and really sticks inside of the strands well. After that I tie it off to a nail, and hang it in big loops from nails in the rafters in the ceiling of my shop. I just use my fingers to take excess slurry off. It works great. After it is dry, usually about 3 days just to be sure, I cut it into 3ft segments and store it in capped cardboard tubes. I really don't use it too much anymore. I tend to use thinner BM from quickmatch for just about everything except matching and making the passfire for spolettes.

Edited by Mumbles, 15 July 2010 - 02:41 AM.

[The Lizard]

Thanks
The black match which I have made I could use as a taper and I have found that when you dip string in KNO3 that also works well as a taper.
Thanks again
Niall

[PyroSkitz]

haha, meh if you found my information usefull, i find that my BP sticks pretty well to the string and i havnt had any flaking off, and yes thick kn03 string makes a fantastic taper for lighting fuse, even in very windy conditions it works