Follow the instructions on your bottle cutter to adjust the rollers, making sure the area to be cut rests on the scoring blade. When you have a good fit and the jar is snug against the blade, rotate it in a counterclockwise direction. As the blade hits the glass, you should hear a scraping sound. When the score has etched completely around the bottle, you might hear a crunch. A dusting of glass power might land on your cutter, so watch your fingers.
Check the score line on the bottle; it should be a faint white line that goes all the way around the object. If any section of the line is missing or too thin, the bottle will not break properly, so put it back into the cutter and score it again. Ideally, you should score the object only once, but you might have to practice a few times to get the hang of it.
You should now see the score line through the depth of the glass. If so, tug gently on the top portion of the bottle to complete the separation. If tugging doesn't work, tap the top section of the bottle gently on a hard surface covered with a dish towel and try tugging again. If the bottle will not separate, let it sit for a few minutes before attempting the separation again.
Once your bottle is fully cut, wrap the unwanted portion in paper or plastic and throw it away. The edge of the remaining section of the bottle might be rough and jagged, so use the sandpaper to smooth it out. Also, clean it very well to remove any tiny shards of glass that may have been created by the cut. Wipe your work area with damp paper towels and throw them away to minimize the chances of embedding glass into your skin.
Decorate your cut bottle or jar as desired. Set up a spray booth and transform the project with milk glass or frosted spray paint. If you enjoy brushwork, there are many high-quality glass paints you can use to make flowers, symbols or other designs on the glass. Explore other design features—one easy idea is to line the edge of the glass with copper tape. You can also mask out chevrons or other patterns on the glass before spray painting. Peel away the tape to reveal the unpainted glass beneath.
Once you've developed some skill with bottle cutting, move on to more complicated bottles and larger sizes. The creative possibilities are endless: Try lamps, cloches, cocktail glasses and terrariums. Don't forget that your upcycled bottles make great gifts!