removing print from glass bottles.

It all depends on what the commercial companies used .

to try things that will not harm the glass, assuming you have none to "risk for experimentation" .

Put one in a container of Muriatic Acid, that will eat a great many enamels, both fired on low temp stuff and epoxy type cold paint, sometimes used to decorate commercially. You can try low heat, but go slow and stop at around

1000 F.

I would start with the acid, and be that it does a pretty good job.

I regularly fuse "painted" glass bottles, like soda bottles at 1500F. I don't think 900-1000 is going to touch it. No experience with muriatic acid, but you can get it at grocery stores as pool shock - handle with lots of care and ventilation.

What are you fusing soda bottles "to"? Don't you run into a compatibility problem? Or did you mean you were slumping the bottles?

I wonder if CLR or a similar product would attack the "paint"?

I tack fused a mass of Skye vodka bottles together once. I still have it. Couldn't convince the Mormons that it was a great suncatcher.

The paint on some beer bottles will withstand the heat of a glory hole.

Jack

I was taking apart the bottles by cutting with a glass cutter and/or partially shattering and assembling the pieces either on a kiln shelf or in thin clay bowl molds painted with kiln wash from Paragon or both and fusing to a firm tack, which also sagged when in the bowls.

I have also preheated the bottles to about 1000F and picked them up with a pipe with a rim of matching glass and reshaped them in a glory hole. The "paint" is an enamel that is normally "silk" screened through a metal screen mask at about 800F and fired on the newly made bottle as it goes the lehr, reheated to about 1100F (briefly then annealed down.)