Anyone ever cut into a GLASS disc? (dont laugh too hard)

[powerstrip]

Hi

Obviously the potential for disaster is very high here. Vibrations on glass. Need i say more.

I met a glass sculptor recently who has been trying to make glass records for a while. She mentioned that it may be strictly ornamental, but at the same rate, i know people engrave into glass often. So maybe it is possible to execute a cut? She fired me a glass blank which i still need to pick up, I'm out of state at the moment.

I was thinking of trying a diamond stylus and cutting at 1/4 speed for delicacy's sake. Any input on this? Absolutely insane? I'm going ahead with it either way. Any input is appreciated. Mainly trying to help someone reach a personal goal.

[Angus McCarthy]

Berliner made his first discs on glass, actually, using the same etching process he later used on zinc discs.

[powerstrip]

Hmmm.... Mr. mccarthy, Please elaborate on this process if possible.

[Angus McCarthy]

It's a simple process, in theory, but finicky and a little dangerous.

http://www.google.com/patents?vid=382790

Beeswax is dissolved in a solvent, such as benzine. This solution is filtered and applied to the surface of the disc. The solvent is allowed to evaporate, leaving an ultra-thin layer of wax "such that it offers no perceptible mechanical resistance to the action of the recording stylus...so delicate that a camel's-hair brush will disturb it perceptibly." This layer of wax is scraped away during recording to reveal the bare glass (or zinc) underneath. This disc is then immersed in an etching solution for several minutes until the groove has been etched to a sufficient depth to allow tracking of a reproducing stylus. For metallic discs, the agent was dilute Hydrochloric acid. In the case of glass discs, Berliner used Flouric acid.

Alternately, if lampblack is used in place of the beeswax coating, photoengraved duplicates may be made from an original glass master - though Berliner notes in the patent that he abandoned this method in favor of direct etching.

On a side-note, I finally deduced what the fountain depicted mounted to Berliner's recorder was for. Immediately before beginning the recording alcohol was let to flow over the surface of the wax, both to act as a lubricant and to separate any dust that may have settled on the disc.

[Techie]

Also during WWW2 when aluminum as in short supply, instantaneious discs were glass based. These, and also Berliners discs utilized a coating that was cut into - not actually etched into the glass itself. That seems like a tough order.

[powerstrip]

Ok that seems like it can work. Ill have to give this a shot. So amazing that I could grab this knowledge before attempting this.

I've definitely read that the glass blanks used during ww 2. But I am under the impression that these were still covered in acetate.

[Techie]

Exactly, the glass replaced the aluminum but the coating was still there. Sometimes a cardboard center was used to lessen the stress of the center hole and drive pin.

[DjMikiRia]

I have researched this much and I always assumed the glass would need to be heated to approx. 900*F to soften it (dangerous), but it never occurred to me to do it this way. Allowing a chemical (acid) to create the depth of groove needed.
I also asked the very same question here on the forum LOL. This sounds much safer that having the glass extremely hot.

[Steve E.]

Check out the thread on gyro's bottle cylinder recorder. He simply came up with a clear variant of the "acetate" (nitro cellulose) used on standard discs. It would be great to know WHAT the heck that was.

https://www.lathetrolls.com/viewtopic.php?f=15&t=3993