Sciencemadness Discussion Board

Silicon Micro-Fuse

BobD1001 - 22-7-2014 at 13:14

I know this is somewhat pyrotechnic related, however it may be of use to anyone finding Goldschmidt reactions difficult to initiate. There used to be a good deal of information on this composition available online, however it seems whatever forum it was has since gone offline and the information with it. As I had it copied in my notebook:

"Micro-Fuse Composition

Potassium Permanganate - 5 Parts
Sulfur - 1 Part
Silicon Caulking - 1 Part

Mix 5 grams of powdered KMnO4, 1 gram of sulfur and 1 gram of silicon
gel ( the substance that is used to glue the glass-panes in aquariums
together ).
I suggest mixing the sulfur 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 sufficient 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.''

I made this composition years ago, and had great success using it to perform many various thermite reactions to isolate certain elements for my element collection.

Today I tried to make the composition once more, and remembered that thinning it with a suitable solvent was an important part of the process, however it seems that I never copied which solvent is safe to use in this composition. Does anyone have recommendations as to which solvent would be appropriate in such a composition? I am concerned about certain solvents reacting with the permanganate causing spontaneous combustion. I know that many solvents can thin silicone: Naphtha, mineral spirits etc. Any suggestions would be highly appreciated.

Metacelsus - 22-7-2014 at 14:50

Don't use anything that reacts with potassium permanganate (so no toluene, xylene, or alcohols).

Aliphatic hydrocarbons (mineral spirits) should be fine.