Blender Comets

--Note: This article was originall published in Best of AFN VII . It contains some "questionable" manufacturing methods and is reposted here for amusement purposes only. Follow these instructions at your own risk--

In our never-ending quest for a better way, many a household appliance has been violated by us pyros. We mill our powder on record players, we mix star comp in washing machines, we evacuate our vacuum ovens with refrigerator compressors. Inevitably the blender would also aspire to pyrotechnic greatness. I've made some pretty nifty comets on this device.

Here's how:

Cases first. These light paper cases are not really necessary to the comet's function, only to its manufacturing process. I cut some 8-1/2x11" sheets of scrap paper in half lengthwise and roll each around a 1-1⁄2" mandrel to form a tube 4-1/4" long. I glue it and then fold the bottom inch over to close that end. It is now a flimsy little cup which will not hold water. I make about fifteen at a time.

Also needed in the manufacturing process is the same number of small rods, 4" or so in length. Old pencils work nicely, so do 16p nails.

My comet formula is as simple as can be:

Potassium Nitrate 800 grams
Water 300 grams
Charcoal briquettes 500 grams
Sulfur 100 grams

I weigh the charcoal briquettes into a can and then bludgeon them with a blunt instrument until I am satisfied that the pieces will not stall the blender.

Now for the good part. I sneak into the kitchen and heat the potassium nitrate and water on the stove until the nitrate dissolves (about boiling). One convenient property of potassium nitrate is its tremendous solubility in hot water. At room temperature it will precipitate, forming a rock. Now I pour the steaming hot solution into the blender. With the blender whirring merrily, I add the charcoal and sulfur. Ahh... savor the succulent vapors of hot saltpeter and brimstone! When was the last time such a tantalizing aroma emanated from your kitchen?

The mixture is now marginally ignitable. To remind myself of what I am doing, I sometimes take a sample outside and light it, then ponder whether I really want to be whipping the stuff up in an electric appliance. Sure, I keep a bucket of water handy.

After blending full blast (whoops) for about five minutes, meanwhile persuading the charcoal chunkies to enter the vortex with a spatula, I'm pleased to see a smooth gunpowder-type puree. At this point I work quickly, lest it form a rock in the blender; after it cools it will be as solid as the potassium nitrate precipitates.

I pour 100 grams of the hot slurry into each of the comet cases. At this point an interesting phenomenon occurs. The slurry becomes stiff and unpourable after sitting for a minute. Agitation such as whipping it with a spatula or rapping the hot comet on the table causes it to re-liquify. My chemical engineer friends call this a thixotropic or shear thinning fluid, but none of them have offered an explanation as to what magical intermolecular forces are the cause.

While the comet is still hot and gushy, and reminding myself not to get carried away by Freudian implications, I make a center hole by pushing one of the rods, nails or pencils into it. I pick up the case and rap each thixotropic comet on the table several times to summon the magical intermolecular forces and settle the composition. When the comets cool, the rods are withdrawn. The resultant center hole makes for fiercer, more reliable burning.

I launch my blender comets from a 1-1/2" tube with 10 grams of black powder. The effect is a pleasant lingering tail of soft orange sparks.

For a yet more pleasing effect I can add some garnishment. I take a string of 16 firecrackers and bend it into a semicircle. I stick a pack into the paper case before pouring the comet puree. Thus, the comet will crackle loudly as it ascends.

The only remaining problem is to clean the charcoal out of the blender and off the kitchen table before the Mrs. returns. Be prepared to answer embarrassing questions like "Darling, why did you put pepper in the daiquiris?"


Previous article Blender Rockets
Next article Microjet Stars - Using Potassium Perchlorate