Some time ago I claimed that I was working on a new type of fuse that i would describe fully when it was sufficiently developed.
Well, now I am satisfied that I have a very reliable recipe, so here it is:

Mix 5 grams of powdered KMnO4, 1 gram of sulphur and 1 gram of silicon gel ( the substance that is used to glue the glass-panes in aquariums together ).
I suggest mixing the sulphur and KMnO4 first to insure a sufficiently uniform mix.
Knead this mixture well, and then roll it out with a board so that You end up with a cord of about 4 mm thickness.
Let it cure overnight and then cut it up into suitable lengths.
The final step is to wrap it in electricians tape ( preferably lengthwise; that is perpendicularly to the normal wrap-up vector ), two wrappings are sufficent with the type of tape that I use.
Now for the specs:

Burn rate: ca 30 sec per 3 cm
Flexibility: A 3 cm piece will bend more than 180 degrees with no damage to the core, though some types of tape may not.
Water Resistance: Core does not soak at all and will survive any amount of rain or submersion. With the described wrappings, fuse will burn submerged.

A variation can be made by using 8.5 g KMnO4 and 2 g silicon gel. This will give a less mechanically stable product, but will burn at a rate of ca 40 sec per 3 cm and will produce less smoke. Water resistance is similar.

Bear in mind that KMnO4 is unstable with many (if not all) fuels, anyone attempting this should search through the forum for references to KMnO4. I certainly wouldn't want to knead this with my hands!

It sounds like an interesting fuse, and all chemicals are available in just about any town. How reliable is it in terms of going out?

J

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The combustion leaves a hard slag behind, which is very hot- in fact it is hot enough to ignite the fuse so if you try to extinguish the fuse but fail to remove the slag, it will simply re-ignite.

Regarding the stability.
This is really not much of a problem; if You are worried that the KMnO4 will react with the sulphur, just leave it out and use the alternate recipe.
Silicon gel is very inert chemically; even fairly high concentrations of H2SO4 or HNO3 leave it intact.

Sounds like a good idea! I've got a tube of silicon glue stuff *somewhere*, I'll try and dig it out and have a go.

J, you could probably use another, more stable pyrotechnic comp besides a KMNO4 based one. The good bit is the silicon glue, flexible, mouldable and totally waterproof.

[This message has been edited by Anthony (edited July 23, 2001).]

any suggestions for a more suitable comp.? surely black powder or any other would suffice as long as the core is sufficiently protected

BP or a simliar comp using a chlorate or perchlorate should work.

I don't think there actually is a "core" like in a conventional fuse, as the comp would be distrubted evenly throughout the silicon "sausage".

I've made similar fuse. It is just powdered mix of KMnO4 and S filled into plastic cylinder(empty pencil). It burns as fast as military fuse. It burns underwater perfectly, I've made underwater bombs with it.
KMnO4 mixed with S and silicon souds good, it could decrease in performance if stored if the KMnO4 oxidizes the silicon(what is the formula of the silicone?).

dumb question:

whats the common name for KMn04?

Potassium Permanganate, the oxidiser used in Flash powder.

KMnO4 - pottassium permanganate,
if you go to a pharmacy to buy it, ask for condi's crystals. it's not a brand name, just as it's called when you buy it as a disinfectant.

ah goddam it..i knew that...i've got like a kilo of it in my workshop

hmm...i might go buy some sulphur tomorrow then

One of the advantages of a rubber matrix over a conventional shell or tube around a powdered core is that it gives much better mechanical stability and is less likely to flash around the core, dramatically increasing the burn-rate. Another plus is that it burns very slowly so if a long delay is needed You won't have to use several meters of fuse. The rubber matrix insures that the burn-rate will stay constant whereas a homemade "hose"-type of fuse could react to mechanical abuse by forming pockets in the powder-train, thereby making it highly unpredictable and unreliable.

Blackpowder may work, as may a great number of other incendiary compositions, but whichever composition is chosen it must burn hot and slow and with a relatively low gas volume.
Otherwise the slag may be ejected and the fuse may be extinguished.

maybe dumb question:
What is the chemical formula of the widely used silicone?
A polymer .....O-Si-O-Si.....? buy what is coonected to the spare 2 bonds of the silicium.

Acetic Acid is often used as a curing agent. What else is in there, I don't know.

J

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Thanks Microtek, one of those great discovers, achievements that makes things easier and fun. Have to test it though hehe.

The other bonds in silicone can be taken up by many things, which is one factor which determines the physical and chemical properties of the silicone. I *think* that H is used in harder silicones as it produces straighter chains and therefore more Van der Waals forces holding the chains together. Larger groups produce chains that fit together less well, so there are fewer Van der Waals forces, resulting in silicone oils etc.
I was thinking about a fuse like this, with KClO3, rubber cement and K2Cr2O7 as a catalyst. I haven't done any testing though, because I got some Visco and then didn't need to any more.

Since reading this thread, I have experimented a lot with microtek's silicon fuse. Upon first trying this idea I started with the method of mixing the KMno4, S, and Silicon together with a little Methyl Ethyl Ketone and extruding it from a syringe, as seen on Frogfot's site. After trying this method many times and changing the viscosity each time I found that not only was it very messy but once I got it to the right consistency for the syringe it seemed to dry very weak and couldn't stand much tension at all.

Next, I decided to try a different method. Even though I could have strengthened this (syringe rope) with silicon lacquer I wanted a much stronger core. I decided to try adding much more silicon to the mix than the 1 part suggested. Adding 3 parts (Lexel) brand of caulking I kneaded the fuse dough repeatedly, forming what looked like perfect molding clay. Using a Pasta maker I fed the dough into the rollers and out came a "rubbery sheet". The pasta machine worked very well forming a perfectly uniform thickness. I let this "sheet" cure over night and then fed it into the cutting side of the pasta maker. Out came long perfect fuse strips all the same width and thickness. Much stronger than the first method.

I then took these strips and carefully wrapped them in many layers of tin foil and dipped them in a liquid rubber roof coating called "Snow Coat". After letting this coating dry over night I decided to try it. I took a 2 liter pop bottle and filled it full of water, taped a nail to the fuse so it would sink, lit the tip of the fuse, waited a few seconds and put it under water.

This fuse could not work any F**king better. It burns perfectly every single time underwater with extremely consistent timing. The extra silicon does not cramp this fuse's style at all! Unwrapped it burns a little like a piece of rubber. However, it does not effect the performance at all. I have never had this go out when burning through small hot glued openings or any other restriction. I would like to add that this "Promised fuse" mix burns so well I no longer weigh the ingredients but just knead the dough to consistency using several different caulkings (Lexel, Silicon, and generic white).

Now comes the bad part,
once the fuse burns past the half way point it is easier for it to push the gasses out the end then it is the top. These gasses are very hot and I believe that if it was used as it is for a salute with flash it could and probably would go off prematurely. My problem is solving this.

I am going to try dipping the end several times in NC lacquer to cap off the end. However, I'm not sure if these gases will push their way through. I need to find a way where the comp is tight enough against the inner wall to only allow the gas to escape up. I have thought of compacting "wet comp" into a metal tube but this leaves zero flexability. Can anyone help with this?

Once your fuze is at the stage that you're ready to put foil around it, try using MEK to just soften the surface enough that it becomes sticky.

Then, wrap the first layer of foil carefully around the fuze material, so as to exclude any voids.

This should make the passage of gasses to the unburned end impossible.

In conversations with Microtek, he indicated that, indeed, the ratios used to make the fuze are very forgiving.

There are available heat shrink tubeings with a liner of a material similar to hot melt glue. Placeing a fuse in this tube and shrinking it from the middle working out to the ends will produce a very tight first coat with no air pockets for combustion gasses to escape towards the unburned end through.

http://cableorganizer.com/heat-shrink/heat-shrink4.htm#B

The result of burning longer lengths of jacketed, gassy fuses is to have them make their own vents at such intervals as the jacket gives way under the heat and pressure built up in the core- Uses where this would be a detriment such as artillery fuses call for gasless (or nearly so) delay mixtures.

What about deliberately weakening the jacket at intervals, so the gas vents out in a controlled manner, rather than possibly building up and blowing through the fuse jacket to prematurely function the detonator?

Thats a good idea NBK, I've experimented with heat shrink before, and it does indeed blow out the side.

I was using black powder at the time, and fairly poorly milled at that. Anything faster/hotter and there might be a problem.

By using a flexible,and resilient binder such as Silicone, Microtek has shown that the fuse possibilities are endless here.
Using Ammonium Chloride, Potassium Chlorate,Lactose and silicone I have been making a very interesting Smoke Fuse. Surely the "rubbery sheet" of Hexachloroethane composition curing inside will be superior though. "prototype sheets" with chemical coloring agents to alter the color of the burn were also a must, we'll see how they come out. Tomarrow I will try a Crackel Fuse with Dragon Egg composition or possibly an Incendiary fuse with Thermate, or maybe A super slow Time Fuse with a Sodium Nitrate & silicone comp. Possibly I will have different colors to the "smoke" fuses , using Solvent dye's.

Much testing to produce the right mix on these variations is obviously needed but there is no doubt that the possibilities are many!

By mixing Potassium Permanganate and Sulfur in the proportions that are founded by Microtek, then thoroughly mixing with a Polystyrene (Styrofoam) and Acetone Gum an extremely lightweight,waterproof and flexible composition can be made. That offer properties competitive to the Silicone binded composition described above. As this is new to me more testing will be needed.

Credit for this binded composition goes to the "Respected Elders" of the EXPLOSIVES & WEAPONS FORUM

The Styrofoam spoke about above was actually a Foam Rubber childrens "sword". I have also been having interesting success with solvent melting TEMPUR-PEDIC mattress rubber and mixing with KMnO4 & Sulfur. These results were the most exciting of all. Extreme flexibility, and stretch strength superior to Silicone.

TEMPUR-PEDIC company gives free samples of their rubber here>http://www.tempurpedic.com/TempurCMSVB/freeinfo/

Not to derail this thread, but I need some help.

I've distilled ethyl acetate and I've tried to make silicone lacquer but for some reason my silicone refuses to do anything but soften up a little bit. This is enough for loading through a syringe, but from the descriptions on Frogfot's site, it should become liquid and homogenous if I add enough ethyl acetate. In my case, The softened silicone just sits in a pool of ethyl acetate and won't suck more up. Therefore, I'm pretty sure that the problem is the silicone.

I use GE Silicone II bathroom sealant in a 300 ml tube.
(http://www.geadvancedmaterials.com/geam/gesa/Residential/en/Products/ProductDetail/gesiliconeiikitchenandbath.html)
Can someone who has done it successfully point me in the right direction? Should I buy the silicone that comes in toothpaste type tubes? (http://www.geadvancedmaterials.com/geam/gesa/Residential/en/Products/ProductDetail/gesiliconeiihouseholdglue.html)

There's also some red high-temp silicone for fireplaces in large 300 mL tubes. I think this may be it but I can't buy some right now. (Having no car in a suburb sucks.)

Could someone just give me a brand name or post a pic of what their tube of silicone looks like? I know this is spoonfeeding but my access to an hardware store is limited and I don't have 30$ to spend on buying every kind of silicone.

Frunk:

There are several diferent brands at Wal-Mart alone, all of which claim to be 100% silicone. Having not tried the experiment you mentioned, I don't know what went wrong, but I would probably not recommend anything meant for high temp, because it likely contains additives.

Methyl Ethyl Ketone or Acetone will work great to thin the brand of Silicone your using, I know this from personal experience. However the silicone will set even though these thinner's are present so I do not recommend storing this lacquer solution. I just mix before use. Almost any Silicone will work for the fuse.

Methyl Ethyl Ketone will work great to thin the brand of Silicone your using, I know this from personal experience. However the silicone will set even though this thinner is present so I do not recommend storing this lacquer solution. I just mix before use. Almost any Silicone will work for the fuse.

You mean that I don't have to waste my time distilling costly nail polish remover to thin my silicone? That works for me :D

I wasn't planning on storing it, I just wanted it to work. It's 4$ for a 300mL tube of Silicone, I can always make more when it's needed.


Out of interest, what does ethyl acetate work with, those acetic acid scented silicones?

Using Ammonium Chloride, Potassium Chlorate,Lactose and silicone I have been making a very interesting Smoke Fuse. Surely the "rubbery sheet" of Hexachloroethane composition curing inside will be superior though. "

Patent info for a "SMOKE CORD" here >http://www.google.com/patents?vid=USPAT3881420&id=6vEzAAAAEBAJ&dg=flameless+pyrotechnic+composition&jtp=1#PPA2,M1

This product is also used for fume generation to disperse chemicals like tear gas

After reading this Patent I'm beginning to think that a good way to make Microteck's Fuse would be to mix the Potassium Permanganate and Sulfur with Vinyl Resin and Dioctyl Phthalate Plasticizer and thread a cotton string through a paper cup of composition, just like you would Black Match. After drying dip in rubber protective coating.

Hot damn!! I cant believe I found this, another perfect example of the Smoke-Gas Fuse/Cord possibilities and with Silicone no doubt !>http://www.google.com/patents?vid=USPAT6552660&id=V5QOAAAAEBAJ&dq=smoke

I made a great fuse today that is an accumulation of fuse ideas off the web. Many of us have a hard time getting oxidizers that have only uses in pyrotecnics. KN03, Magnesium, Dextrin (heat corn starch in oven till golden brown) put togeather makes a great burn mix at *about* a 8:2:1 ratio play around with the mix untill you have a good mix that burns evenly and burns relativly slow (for a flashpowder).

Get an old shoe lace, a syringe (pharmacy) and put your mix into the syringe. stick the syringe into the shoelace (with insides taken out, so you are left with a hollow string) and shake it up and down to fill the string full of the mix. Tie it off and coat the string in NC laquer.

Done! Now you have unlimited amounts of homemade visco!

Possibly I will have different colors to the "smoke" fuses , using Solvent dye's.


When I had originally said this I had planed on using a mixture of Potassium Chlorate, Lactose,Solvent Dye Pigment and Silicone.

After sufficient testing I have concluded that no alteration to Microtek's original Fuse composition is necessary. Achieving a steady stream of rich colored Smoke comes easily by simply "kneading in" Solvent Dye Colored Pigments into the "Promised Fuse" Dough.

The Gas Stream created from the Fuse burning under pressure in the jacket, propels the colored particles smoothly and effectively without seeming to burn to hot.

A person with a pallet of colorants and an "eye" for mixing colors could achieve any Color of Smoke desired while still maintaining an effective underwater or "all weather" Fuse.

I will post pictures after the variety of colors I have mixed "cure".

*By the way, good old paint thinner mineral spirits thin silicones very well and are somewhat less agressive with plastic containers than MEK and acetone. Some of it gets trapped in the silicone and helps to lower the ignition temp.

It's about 5 bucks for a gallon...*

Hi
If the length is not a problem I think we can use thermoretractable tubing used in electronic and other electricity cabling. These tubing are sold in different diameter (and color) but usually black and one meter long.

The chemical mixture putting in it must not init or react violently to a temp of about 100° Celsius. This is about at this temp the tubing is going to retract.

I will test soon and tell you the result.

PETN & Silicone sounds possible. And if you need an illustration of just how bewildering a variety of silicones there is out there, Google "Gelest" corporation. They've got literally hundreds of formulations, ranging from marine sealants to aerospace grades to biocompatible stuff for surgical implants. I haven't seen their website, but their print catalog will absolutely smother you with the attendant chemistry.

By the way, if you need to thin silicone without contaminating it or otherwise altering the cured properties, might I suggest Methyl Siloxane. It's not that expensive or hard to get, but wear a respirator, just to be on the safe side. I'll beat the bushes and see if I can find an easy source, if anyone's interested.

kaboum,

You are looking for the name "heat shrink". You can buy it in nearly any diameter, and you can get low temp shrinks, as well as 2:1, 3:1 and now even 4:1 shrink ratios, and on reels of 100 meters if you want it.

Be interested if you get some results up.