Is an internal crack in a homemade bottleneck guitar slide dangerous?

July 23, 2020 8:12 AM

Posting for a friend -- Following this tutorial I cut off the end of a wine bottle for use as a bottleneck guitar slide. Everything went fine except the slide has a crack on the top. The crack is internal; it can’t be felt by touching either the inside or outside of the slide. How threatening is this crack to the longterm integrity of the glass? Could the slide explode on me at some point, possibly while I’m playing guitar?

imgur album with images of the crack here

posted by matcha action to Sports, Hobbies, & Recreation (11 answers total)

Don't chance it. I've had a real tempered-glass slide break before, and a bottleneck is a lot less likely to break in a safe way. Even invisible cracks compromise the structural integrity of glass.
posted by aspersioncast at 8:16 AM on July 23, 2020

I'd be worried about small shards of glass breaking off of it and giving the player glass splinters. They can really hurt.

I don't think it'll explode or anything. It may just crack in half one day while you're playing it.

The process looks fun, why not just make another?
posted by bondcliff at 8:17 AM on July 23, 2020

Looking at that picture -- oh hell no. I have seen even smaller cracks in drinking glasses fail, and those aren't being pushed up against something and slid around. Sorry, but you can chalk this one up to practice and make another one. Unless you want to wait for your hand to heal so you can play again.
posted by fiercecupcake at 9:01 AM on July 23, 2020

The way I learned to do this was to soak a piece of string in kerosene, tie it around the place you want it to break, light it up, then dunk it in water. YMMV. It will eventually break, not explode.
posted by zengargoyle at 9:10 AM on July 23, 2020

Worst case scenario is that a shard of glass slices a tendon, ending your guitar-playing days. It's really not worth the risk.
posted by essexjan at 9:13 AM on July 23, 2020

I'm a steel or brass guy. If having a fun project is the goal you're on track I think. If not, there's a lot of commercial options. Dunlop has the Derek Trucks simula Duane Allman coraciden bottle.Rockslide has much heavier/thicker options.
posted by j_curiouser at 9:27 AM on July 23, 2020

Interesting video, thanks! Instead of, or in addition to his final step with the sandpaper, I'd do something I learned in the chemistry lab: position the cut end just above the blue flame of a gas stove burner, and rotate. Get that new edge red hot, and then set it aside and let it cool -- the heat should smooth out the roughness. This step might also reveal and aggravate a crack like yours to expand such that you'd know you have to try again.
posted by Rash at 9:37 AM on July 23, 2020

The instant you pull a little too hard on the high e side and bump a fret, that fucker's gonna cut you.
posted by notsnot at 10:47 AM on July 23, 2020

It would be actively dangerous to play the guitar with that slide.

Fire polishing such as Rash suggests will not work with any commonly available glass except borosilicate glass, and I've never heard of a wine, whiskey, or beer bottle being made with borosilicate glass. Exposing a chunk of the average wine bottle to the heat of a gas flame could cause it to explode.
posted by jamjam at 11:40 AM on July 23, 2020

aiii! I strongly recommend against. The worst cut I ever had was from a (kind of heavy) glass coffee cup with a small crack that I was washing just to use as a container for pens, etc. Put my hand inside the cup to hold it while washing the outside and it broke on my hand / fingers ... so. much. blood. Luckily, I didn't sever anything important, but it was a close thing and pretty traumatic. These days I don't save cracked glasses, cups, bottles, bowls or similar for any use.
posted by taz at 4:33 PM on July 23, 2020

Thank you all! I Appreciate the help. My friend will take another try at it.
posted by matcha action at 10:37 AM on July 24, 2020