Apparently there are no good guides on how to make proper homemade slush, so I'll try to explain to you how to make one.

There are three key factors in the making of slush;
  1. a good blender (The detachable top of a decent food processor will do fine here),
  2. a lot of ice cubes, and
  3. flavour (use concentrated lemonade or other sweetened drink you blend with water).
Timing is essential. If you do not time it correctly you will find yourself with a bowl of colored snow instead of ice cold slush.

The process

  • Fill the container in which to produce this lovely drink with 12 (twelve) ice cubes.
  • Now, with the ice cubes placed inside the container, fill it with your flavour excactly half of the height occupied by the ice cubes. If you do this wrong, you will not be able to blend it correctly.
  • Position the speed control of your food processor at the lowest speed, preferrably 1 (one).
  • Flip the switch.
Watch as it slowly (rapidly?) crushes the ice cubes into shape (actually, it's not a shape, it's more like chaos) and blends it with the lemonade. At any point now you may increase the speed of the food processor, just make sure that you do not liquify the ice cubes by going at a far greater speed than you're supposed to.

If you've done this the right way, your ice cold slush should be just about ready after a couple of minutes. If you've done this the wrong way, your slush may still be consumable but deals a great amount of impact to your slush experience.

Troubleshooting

So you did it the way I told you not to do it, didn't you? Shame on you. Your error may be irreversible, and you may have just lost 12 precious ice cubes. On the other hand, there may just be hope for you. Let's look at the possibilites:
  • You tried to use Coca-Cola or other sweet drink containing carbon dioxide (CO2). There is really nothing to do with this. You end up with a ice cold soft-drink with no carbon dioxide. I've tried, and I do not recommend it to others.
  • You tried to make the process faster by using a higher speed on your food processor, and no more ice cubes are falling down to the crusher section. It is, in theory, possible to make a decent slush out of this, but it will be kind of watery. What you do is that you flip the switch to turn it off, open the lid, poke the ice cubes around a bit, and then try again on a lower speed. I have no other solution.
I hope this writeup has helped you in the very difficult process of making decent slush at your own home. Let the slush flow :)


Update 2002-10-10: thanks to toalight for correcting some of my grammatical errors.