The only procedure that consistently gave me relatively clean breaks was the following. Safety glasses and leather gloves are probably not a bad idea though I've never had any bad experiences with the procedure below.

1. Draw a line around the bottle neck with a magic marker.

2. Score around the line (only once) with the edge of a triangular file . Using a triangular file allows you to press down firmly with your thumb directly over the scoring edge of the file thus creating a score of more consistent depth. It is important to score only once and try to make a score line of consistent depth otherwise the bottle breaks unevenly. I practised on beer bottles first to get the feel of the procedure and then moved to thicker glass.

3. Heat the score in a candle flame while rotating the bottle. Soot is deposited where the flame touches the bottle so you know you are hitting the score line evenly.

4. While hot, rotate the hot score under some cold running water. Usually, it breaks cleanly. Most times, you can essentially pull the neck off the bottle. No tapping, smashing, etc. to potentially send glass shards flying around the room. [Glass shards on the kitchen counter/floor makes my wife angrier than practising the same song for hours on end while enjoying the tone of my newly cut slide.]

5. If neck doesn't break the first time, then dry the bottle, reheat the score and cool it again. The thicker glass usually required two heating/cooling operations.

6. Then file and sand smooth.

The reason that I chose this type of file is two fold. One for leverage and two because my instructor in a laboratory glass blowing short course demonstrated that this type of file was very efficient for scoring and breaking glass tubing. For tubing, one just needs to make a score about one third of the way around the tube to break it cleanly. Interestingly, if you score a glass tube all the way around the tube it doesn't break cleanly perhaps due to uneven stresses introduced into the relatively thin walled glass. I really wish that I still had access to a oxy/acetylene cutting flame to fire polish (melt) the ends of the slide after cutting.

Happy Slidin'

Just to let you know that I think Diamond bottlenecks are the best sounding ones I've ever used.

My old one got smashed when it fell against a metal mike stand, and I had to get in touch with the boys at tone-toys.de very, very fast for a new one. I was desperate, having to resort to an old Dunlop pyrex.

I got two Diamond bottlenecks this time, one for backup just in case - I think that kind of shows how much I've come to depend on my green glass Diamnond for nice tones.

Thank you for a great bottleneck solution for those of us that don't cut our own - David.

Thanks again, and Happy Slidin'

I used my trusty glass cutter, whose cutting wheel is suppied with cutting oil - a mixture of 3 in 1 oil and turps. if you dont have such a beast just dip your cutter in white spirit.

I found it impossible to run a continuous cut all around the neck, but used a series of small say one inch scores. - on no account double up over a score, do it once only. Best use a piece of masking tape with a mark showing your start/finishing point.

Once the perimeter is scored you have to tap around the score with the other end of the cutter.
Good taps but not so you would expect to "smash"the end off in one go.

Keep tapping all around and a crack will appear - keep tapping and chasing the crack around and off it comes.

I did 2 bottles in minutes - even took the annoying lip off the cork end (about 1/4 of an inch) using the same technique.

Having mentioned that I'm a stained glass hobbyist, I have a glass grinder - they cost a lot here in the UK but when I was over in St Louis they were a fraction of the price we pay.
This has a water bath so that theres no dust coming off.
Worked great and plays just great.

A tile wet saw.

I've got one because I am a tile and stone contractor so I thought before I give this sage advice I'll go out to the garage and try a couple. Worked 6 out of 7 times clean as a whistle. The one that failed was a thin beer bottle neck that you wouldn't use for slide anyway but the three thickest ones were the easiest and cleanest. Now some of you are probably saying that that's all well and good but you don't have a wet saw. Well every Home Depot does. It's at the end of the tile aisle and it's for weekend warriors to get their more complex cuts done. The one near me lets all the homeowner Joe's make their own cuts so that situation would be easy but if the one near you has the staff do it just slip 'em a 5 spot and off you go. Or have your wife ask 'em that always works. Either way you might have to buy $3 worth of tile put some marks on 'em and pretend you need some cuts done and slip the bottle in at the end. This will work. Home Depot people do not care about things like this.

I use a Grinder indeed a wonderfull AND VERY NOISY tool ! Its not very good for chasing women but its Very very masculine ! After the noise and rain of glass all over the place I have a lot of sanding to do. I like machines so i use another machine:

(My GranDad spent time as a glass cutter in the '30s so these first two are from that era)

Burning Thead method: Kerosene and real Wool yarn (it HAS to be 100% sheep's wool) I'm guessing bottle orientation affects this method so it may take a few more "dead soldiers" to perfect it.
Soak the yarn in the Kerosene. Tie tightly around the desired break point. Light the yarn, let it burn.

The previous posts that indicated single scoring was key falls in line with his missives as well, "Score once, score right or throw it away and start again"

(Last thing)
Back in the '70s it was popular to make chandeliers from different color wine bottles. (You cut the bottoms out and hung several (bound together) by wires in their necks) I remember a jig that basically held a hand-held glass cutter under tension as you rotated the bottle. Then there was a long slightly angled tool with a small weighted bulb as a striker that you inserted into the bottle(thru the neck) to tap-tap the score from the inside. It was supposed to give a flat clean break. Prolly a "Ronco" product but the technique may have merit.

Slide On!

Ian.

Slide On!

Ian.

Slide On!

Ian.

Slide On!

Ian.

Also...when you go into a shop and pull a guitar of the wall and sit down to try it on...the salesmen will come flying when they see you pull a deep socket out of your pocket...really terrifies them for some reason...probably think you are going to disassemble the thing or perhaps change oil... ...

Slide On!

Ian.