Weird ignitor problem?

[HVD]

I'm trying to make ignitoers by dipping the bridge wire assembly in a mix of double base powder (bullseye to be precise) and acetone. I've used just enough acetone to get the DBSP into a thick, slightly runny black paste.

I've tried using steel wool (which thrown out white hot fragments) and thicker strands of steel thread that just glow red hot. However my ignitors just seem to fail to ignite the set DBSP! I can't think why this is, as I've read about quite a few people using this method to make ignitors.

The bridge wires ignite the DBSP when it's loose, just not when it's set into a hard mass around the bridgewire. Even the red hot bridge wire just makes the set DBSP smoke and fizzle a bit.

Any ideas? Lots of other people seem to be able to get this method to work?

HVD

[yt2095]

this may sound like a dumb question, but do you let it go completely dry first?

Here`s the method I use, it may or maynot be of any use to you, but on the off chance, here it is.

1. I don`t use wire wool. I use a single strand of multi strand buss wire.

2. cut a 2" length and attatch one end to your main current wire (solder helps but not essential)

3. get the thinest needle or pin you can find and make a coil with your thin wire by wrapping it around the pin and making sure all the winds are touching.

4. attatch the other end to your current wire, you`ve now made a crude bulb.

5. I use wetted crushed safety matches in a paste to cover my coil (you could try a version this way or use your DBSP paste)

6. when entirely dry I coat in NC laquer (ping pong balls and acetone) if I have none, nail varnish will work too.

the advantage of this method IMO is that the heat is greater and the coil lasts longer before breakage. it WILL however require more power than your wire wool ignitors. I use a hand cranked generator to charge a capacitor for mine (36 volts under load).

hope this helps a little :)

[HVD]

Originally posted by yt2095
this may sound like a dumb question, but do you let it go completely dry first?


Well, i thought at first that it might just still be a little damp. But i made a second batch (of three ignitors) and left them on a sunny window ledge for about 4 hours. They certainly felt very dry. I noticed the skin had sort of crinkled up a bit around the ignitor, i suppose that could be acting as a barier stopping the acetone from the inside evaporating quickly?

HVD

[yt2095]

Hmmm...

yeah, that skins normal and so`s the crinkle effect (be carefull as the shrinkage can snap mono fillements, that`s where the coil technique helps too)

a good way to test is put them in a plastic bag or clean jar for 10 mins, then take a sniff, if it still smells like acetone, they`re not dry (I use this in multi layer nail varnish coats to test if its dry)

[Mr Cool]

Adding a bit of BP or matchead powder to your DBSP will probably help it to ignite.

Another way to get very robust ignitors is to wrap some fusewire, nichrome or whatever around a 5mm length of cotton string that's been soaked in saturated NaClO3 solution and left to dry. Then coat it all in the varnish of your choice, and let the varnish dry. The string will ignite easily from a red-hot wire, and as well as making a big hot flame, it spits out bits of ash, slag, burning stuff etc, and they burn for a second or thereabouts, so it's got plenty of time to get things going.
A little bit of blackmatch fuse will also work very well in place of the chlorate-soaked string, as will anything which ignites easily and burns fiercely.
I prefer this method to coating the wire in a pyro comp, since it makes very sturdy little ignitors. If you coat a wire in pyro comp, then it will break off very easily if you're not careful.