50 Gauge match head trouble

[ChloRure]

I was tired of trying to solder nichrome wire, so I decided to buy some ODA 50g match heads. I followed the dark flash (50/50 kclo3/antimony) formula, about 1/16 dip.

 

Problem is that they just blow when I put voltage on them, they never catch fire. They work if I use 1 AA battery, but I built my systeme with 12V.

 

I use a 12V 1,2a battery with 100feets wire and they blow, but if I try homemade ematch with 40g nichrome, it work without any trouble, I can even apply voltage for 2-3 secondes (nichrome get red hot) before it breaks.

 

Any idea to get those work with 12v ?

[BlastFromThePast]

I'm no expert on this stuff really, but it sounds like when you're using the 50g heads with the 12v system you're vaporizing the wire with all of the power you're applying and the 40g is able to withstand that power and "gently" heat up slow enough to allow for the pyrogen to ignite rather than ignite all at once. There honestly might be an easier way to trouble shoot this, but my suggestion is incorporate a secondary resistor into the shooting wire. Start with smaller values and work up. See how much added resistance it takes to allow for proper ignition. If you're going to plan on using the 50g match heads as well as the 40g heads in the future you might want to buy some cable splicers such as the ones below and have a few sets of shooting with that will have the best valued resistor that you found above spliced into your shooting wire simply for your 50g heads. I know that's a lot and again, there might even be an easier way to do it but this is just my 2 centshttp://www.buyheatshrink.com/heatshrinktubing/Pics/Splices.jpg Edited April 10, 2013 by BlastFromThePast

[Mumbles]

You might want to try putting a more flame producing pyrogen, such as BP or BP with metals, over the top. This will help propagate the flame, as well as reduce some of the direct sensitivity of the match head.

 

When you say blow up, do they still light anything? Commercial electric match goes off with a snap and not really much visible flame, but they still light quickmatch and lift charges quite well.

[ChloRure]

You might want to try putting a more flame producing pyrogen, such as BP or BP with metals, over the top. This will help propagate the flame, as well as reduce some of the direct sensitivity of the match head.

 

When you say blow up, do they still light anything? Commercial electric match goes off with a snap and not really much visible flame, but they still light quickmatch and lift charges quite well.

 

I dont see anything, I test them with ohm meter and they are not working after the test. No sound, fume, flash... nothing.

My NC solution is probly more around 12%, ODA ask for 2-3%, is this can be a problem ? How can I lower my %... I tried adding some acetone.

[Nessalco]

There are a few factors to consider when dipping ematches. First, your chemicals must be very finely divided, and pass a 100# screen at minimum - especially the potash. Your NC lacquer consistency is a potential problem - it must have enough NC to bind, not enough to trap bubbles. Five percent is about right, twelve far too thick.

 

When you make your dip, let it sit for a few seconds after mixing. This will allow most of the air bubbles in the slurry to rise out. Ditto when you add acetone to thin the slurry and have to stir it - give it a few seconds to settle before you start dipping again.

 

Finally, ditch using the 'darkflash' prime, and use straight H3 for both the first fire and the pyrogen. Always lights, and is not so energetic that it ruptures the match head. A simple overcoat of NC lacquer will reduce the friction sensitivity, and will cause the match to 'snap' much like a commercial product. Ten grams of H3 in a slurry is more than enough to dip 50 ematches - you could probably do 100 from 10 grams if you kept on top of the consistency.

 

Kevin O

Edited April 11, 2013 by Nessalco

[dagabu]

There are a few factors to consider when dipping ematches. First, your chemicals must be very finely divided, and pass a 100# screen at minimum - especially the potash. Your NC lacquer consistency is a potential problem - it must have enough NC to bind, not enough to trap bubbles. Five percent is about right, twelve far too thick.

 

When you make your dip, let it sit for a few seconds after mixing. This will allow most of the air bubbles in the slurry to rise out. Ditto when you add acetone to thin the slurry and have to stir it - give it a few seconds to settle before you start dipping again.

 

Finally, ditch using the 'darkflash' prime, and use straight H3 for both the first fire and the pyrogen. Always lights, and is not so energetic that it ruptures the match head. A simple overcoat of NC lacquer will reduce the friction sensitivity, and will cause the match to 'snap' much like a commercial product. Ten grams of H3 in a slurry is more than enough to dip 50 ematches - you could probably do 100 from 10 grams if you kept on top of the consistency.

 

Kevin O

 

Great advice Kevin. The 50ga wires don't like 12V or big Capacitive ignition much, "snap" and they are gone. I will try your H3 idea, thanks again.

[ChloRure]

Yes, good advice. Will try this test this weekend. Any idea how to lower my nc %?

[Mumbles]

Dilute it with acetone or whatever other sort of lacquer thinner you feel like really.. If you have 12%, diluting with an equal volume of solvent will give you 6% w/v for instance. For these sorts of applications an exact concentration isn't critical, only ballpark.

 

There is a formula that you might find handy. C1V1=C2V2 Where the C is your concentration, and the V is the volume.

[ChloRure]

Dilute it with acetone or whatever other sort of lacquer thinner you feel like really.. If you have 12%, diluting with an equal volume of solvent will give you 6% w/v for instance. For these sorts of applications an exact concentration isn't critical, only ballpark.

 

There is a formula that you might find handy. C1V1=C2V2 Where the C is your concentration, and the V is the volume.

 

Thanks for the formula. The vendor told me it was around 12%, but dont have the exact cencentration. It is yellowish and have a semi think sirop.

[Arthur]

The issue with 50# is that there very little metal to melt so it will fuse on low power like a trade igniter, BUT this means that there is very little energy to pass to the pyrogen. SO it's essential that the ingredients are fine enough and that the first dip contains only just enough NC to bind it,

Try 200 mesh or finer for the ingredients (you will need so little (0.2grams) that a mortar and pestle will do. Calculate the quantity of NC Lacquer so that the NC is really about <5% of the pyrogen.(exc solvent).

A second dip of coarser chlorate free pyrogen assists flame production, a third dip of plain (or coloured) NC adds abrasion resistance.

A good 50' ig will perform exactly like a professional ig and will fire from long wires or big CD exploders.

[WSM]

Most of the suggestions are very good. The key problems are covered. If you still experience failures, be certain your pyrogen mixture is freshly, well-mixed and degassed (bubbles removed). If bubbles in the matrix are next to the bridgewire, they're likely to cause a failure.

 

Intimate contact with the bridgewire is a prime requirement of the pyrogen.

 

If metals or other conductive components are part of the pyrogen, be sure they're a low enough percentage that they won't short out the ignitor (that is, shunt the electric power past the bridgewire), creating an unreliable ignition.

 

Just some thoughts to consider...

 

WSM

Edited April 15, 2013 by WSM

[BurritoBandito]

Another idea would be to put a potentiometer on one of your leads. This would allow you to adjust the resistance on the fly so you wouldn't have to keep testing resistors until you found the right value.

[ChloRure]

Well, I started to work on those igniter again last week... here are the results i got now.

 

On around 40 igniters, only a few worked (using AA ) battery to test.

 

Most of them just do POP loud enough without igniting, you can see part of the pyrogen missing. Sometimes the nichrome still glowing...

I was using darkflash as first primer, tried only H3 and it was total failure.

 

To be sure I dillued my unknown nc lacquer % to 1/4 nc/acetone.

 

Any idea what I am doing wrong? I got this pop even with thin coating.

 

I think my next move is to try with smokeless powder nc lacquer... 5g / 100g should give me 5% nc right?

[Mumbles]

These things really don't sound like problems to me. I think you might be better off doing a more practical test. Put one of your match heads into a short segment of quickmatch or a small baggy of black powder. If they ignite, you're fine. If they don't ignite, then you can worry. An e-match might be a bit of a misnomer. There really is no visible or sustained flame on them, just an electrical igniter. Commercial ones behave exactly like you're describing, and really produce no actual noticeable flame.

[Nessalco]

If you weren't able to get H3 to work, my first thought is either the quality or consistency of your chemicals. Charcoal must be airfloat, and the KClO3 must pass #100 screen at a minimum.

 

What are you using for NC? I've used both Skylighter's product and NC made from Bullseye powder with complete success.

 

I recently bought a CD firing system, and just for giggles hooked up a single ematch to it. Worked fine, so the energy of the firing pulse isn't your culprit.

 

Kevin

[Nessalco]

Oops, just read the last line of your post again.

 

Five grams of Bullseye or Red Dot in 100 grams of acetone will give you 5% NC. A couple things to watch out for. Work in a well-ventilated area. Besides the acetone, you will be producing nitroglycerine fumes, which can give you a pounding headache.

 

You can't just drop the two components in a jar and give it a shake. Given half a chance, the powder will clump and you will never get it to dissolve. The best process I've seen involves whisking the powder into the acetone using a stainless steel kitchen whisk in an open bowl. Whisk like mad until the powder is all dissolved and the lacquer thickens, 2-4 minutes. Cover tightly and let sit for 30 minutes. Whisk again, and pour into a suitable (metal) can.

 

I usually make this up as 20% solution and then thin it for various uses. Note that a 5% solution of powder-based NC is about the same consistency as ~20% 'regular' NC. It seems quite thick, buts wets out various compositions without a problem. A 20% solution of NC made with Bullseye is very thick - almost like heavy motor oil or corn syrup. It works very well for making dragon's eggs.

 

Kevin

[ChloRure]

The NC I am using right now come from a pyro supplier out of business now. It is yellowish pale color with a mapple syrup viscosity.

 

What I dont understand is that I got a batch to work... darkflash mixed with 1/3 nc/acetone ratio, dried 1 day then coated with H3 1/4 nc/acetone ratio. 10 of them fired without a problem, 1 sec flame visible.

I tried to do the same things and this is not working.

 

Also, lets say I mix 1 part of my NC with 4 parts of acetone... dip some head... blablablabla then oh all the acetone mostly evaporate, is my subtance coming back to original nc % ? Cause when this happen, I just add more acetone on the fly but it's hard to know which % I am now getting.

 

Hope you understand what I mean?

[Nessalco]

I do understand. You have to add acetone on the fly to deal with evaporation. There is a certain feel for the proper consistency that you develop after a while. If you get it too thin, it won't cling. If too thick, it won't drip off properly.

 

You also have to stir the slurry frequently, just to keep the chemicals in suspension. Of course, then you need to wait a few seconds so the slurry degases before you dip your next batch. At normal room temperature, I can usually dip 50 ematches without adding acetone, but I have to stir 5 times - I do them in groups of ten. Dipping all 50 only takes about 3 minutes, so evaporation is not really a problem for me. When I do add acetone, I use an eyedropper - it's just a few drops. YMMV.

 

Also, try drying your chemicals. KClO3 can pick up a bit of water, and charcoal will suck it up like a sponge. If you're getting any clumping at all in the other component, dry that as well. Usually moisture is not a problem with that one. Dry the chemicals separately, before any mixing occurs.

 

Kevin

[dave321]

you could also try butanone as a solvent, this will evaporate slower than acetone dave

[Arthur]

The best wisdom I've found is that the dark flash layer is critical. Separately mill the ingredients use only that which passes 250 mesh.

 

Take 47.5 mg of each and 5mg of dry NC then mix with plenty of acetone and let it thicken. Stir well and dip in that. at 100mesh nothing will fire at 200mesh most will fire. finer and everything works. use only just enough NC 5% is plenty. Make VERY little 1ml will dip enough igs. DISPOSE of the waste very carefully. fire it remotely if you can.

[Nessalco]

The best wisdom I've found is that the dark flash layer is critical.

 

Maybe I lead a charmed life or something, but I've had 100% success using just H3 on #50 match heads. I've made around 600 that way, and fired 300 of those - the other 300 are for this year's show. I have no doubt they'll work just fine.

 

I used to use darkflash as a first fire, but ended up trying just H3 trying to avoid just the phenomenon the OP is describing - the head fractures and goes flying in an open air test. Using H3 worked, and worked well - even when coated the match gives a snap and then flares with a visible flame. Anything I can do to simplify the process is worth it - and using one formula for both first fire and pyrogen is handy.

 

Good NC is critical.

 

Kevin

[ChloRure]

I disolved 5g of ping pong balls in 100g of acetone yesterday, should be all disolved tonight.

I will try with this NC and see if it improuve.

 

My antimony is not dark grade... but chinese. But it is very fine powder. As for the kclo3, it was pre ball milled before I got it, and I screen it just to be sure to remove any clumps.

As for my new NC with pingpong, I guess since it's mixed with the correct amount of acetone, I just it straight like this ?

 

Do I really need to wait 1 day after the darkflash coating to test them ?

Edited June 13, 2013 by ChloRure

[Nessalco]

Ping-pong ball NC will not work, or at best, will work poorly. It contains inhibitors to reduce its' flammability..

 

I usually let the first dip dry for an hour before I do a second dip. Works for me.

 

Kevin

[ChloRure]

Well I tried with ping pong ball nc and so far it works! But I used a mortar and pestle to grind more my kclo3 just to be sure.

 

It gives a pop, you can see some of the pyrogen flying but still have a flame about 1/4 sec and i was able to ignite quickmatch

 

Thanks a lot for your help all.

[layedbackkustomz]

To solder nicrome use a good quality flux or try a drop of muriatic acid (the stuff they use to clean pools) its that easy