Berliner-style blanks

[Angus McCarthy]

After doing some serious brainstorming and research, I'm moving towards the goal of accurately reproducing the earliest acoustic disc recording methods.

We know that Berliner initially used glass or zinc discs coated with lampblack but eventually switched to coating the surface with beeswax dissolved in gasoline - which was allowed to evaporate, leaving a super-thin coating of wax that was easily scraped away by his recording stylus (still not finding a lot of information as to what was used, whether it was a stylus like we still use or just a thin needle). This disc, which had its reverse side coated in protective varnish, was then immersed in an acid bath to etch away the metal revealed by the recording process.

The two questions left are, firstly, will galvanized sheet metal etch in a similar manner to 19th century sheet zinc, and second, what acid is available that would properly etch the metal while leaving the Beeswax and lacquer alone? As far as I can tell, this is still a very doable method for those who can't acquire or work with later-style wax blanks, since the resulting discs can be directly electroformed into negatives.

[markrob]

Hi,

How about using standard FR4 copper clad printed circuit board blanks and ferric chloride or ammonium persulfate as the echant? I wonder if using a PCB blank coated with wax or other resist would work? PCB blanks specified with 3 oz. copper are about 4 mils thick.

Mark

[Angus McCarthy]

It would probably work, but looking at full sheets at $150-$170 for 12 square feet, it's quite an investment for being untested. I know you can still find solid zinc stock for countertops, etc., but the price range is pretty drastic depending on the gauge. I'd be worried about warping when trying this with the thinner sheets - that's why it'd be great if galvanized steel could be used in place of solid zinc. Though, again, is the layer of deposited zinc thick enough to etch?

[mossboss]

Why dont you get some blank steel plates at whatever thickness you want and zinc plate them yourself?
plating kits are available but its no big deal to knock one up with a some plastic buckets and a DC source or even an auto battery and some voltage control
Zinc is plentiful from junked gear everywhere
If you are brave you can clean the plates with sulfuric acid and hot dip them in a melted zinc bath made out of heavy cast iron
Gas fired it will melt zinc no dramas
That's all galvanising is any way
Keep us in the loop
cheers

[chaosbc]

Pure curiosity : what is the role of the lampblack in this process ?

[Angus McCarthy]

Initially, Berliner used glass plates covered in lamp black, like Phonautograms (which I believe he references in his patent, actually), which would then have acid applied to etch the groove into the glass. This still required the use of gold or silver sputtering to create a negative. His first successful method for easy disc replication was the beeswax-on-zinc method, and he abandoned lampblack as a coating. By the time the company had fully morphed into Victor Records, they were using all-wax blanks (which, again, required graphite deposition, but achieved a much higher level of fidelity).

I wish I had the space to try hot-plating myself, but I don't think the Fire Chief would appreciate a cauldron of boiling zinc in the middle of a heavy residential zone!

This is one of the few remaining zinc discs from very early on - cut, etched, and sold out the door!
http://i291.photobucket.com/albums/ll283/phonogfp/gramo5inchzinc.jpg

[Techie]

re: the cutting stylus - I have read that the cutting stylus used today was developed because of the change to lacquer from wax. They have facets to polish the groove wall, which was not necessary when cutting into soft wax. The damping of the cutter heads also had to be more intensive than with lacquer. The lacquer blank itself acts as a damper of sorts and the cutter therefore requires a less damping than when cutting wax, which had comparatively less resistance.
If I run across anything more specific about the type of stylus used for wax, I'll definitely pass it along.

[Angus McCarthy]

Here's a very important question to consider in moving forward with this idea:

Assuming one could get a successful result etching the disc, would anybody in the plating side of things be able/willing to form a Master/stamper from the zinc disc?

[Angus McCarthy]

Techie:

Finally tracked down Edison's patent for his wax recording stylus, though whether it's the same type adopted by Victor for lateral wax cuts I don't yet know.

http://edison.rutgers.edu/patents/01024839.PDF

All the pictures I've seen seem to indicate Emile just used a pointed stick to wipe away the sheet of wax from the disc.

[Angus McCarthy]

Well, it looks like I've got two viable choices for the etchant.

One: Ferric Chloride, which was probably what they would have used but produces some pretty toxic compounds as a result of the reaction.
Two: Hydrogen Peroxide + Hydrochloric Acid. This may etch more slowly, but the reaction seems to be a little safer - and the materials are pretty easily obtained from a pool supply store or bigger hardware store.

I'm wondering now whether galvanic etching might work more cleanly, though, since it's usually a slower process.

[opcode66]

You can get Ferric Chloride etchant at Radioshack.

[Angus McCarthy]

Really? You must have an awesome Radio Shack. Mine only sells cellphones any more.

[Steve E.]

Angus, what a great project!!!

[opcode66]

Really? You must have an awesome Radio Shack. Mine only sells cellphones any more.

I know! They still have a compenent isle!

If you have a Fry's or Microcenter (possibly a Tiger Direct) they might have too. They are stocking a lot of arduino stuff now. And, they have components and what not. I just picked up a pcb etching tank kit from Microcenter. Truly suprised me that I could buy one off the shelf at my local store.

[jornibudich]

Hello guys,
I have been following this discussion and is very interesting despite the fact that I am cutting in lacquer .
Just made a post in the Handcrankers section about my last experiment - the links are http://odeonacoustic.blogspot.ca/2013_02_01_archive.html and http://youtu.be/fbxk5O0t-bk.
Would like to know if Angus is working in an acoustic lathe!!
Cheers

[Angus McCarthy]

Hey, Jorni.

I'm taking a page out of your book, actually. I got ahold of an Orthophonic reproducer that I think will work quite well as an engraver once I get the bearings restored. I'm also in the process of cobbling together a purpose-built engraver based on the pictures of Emil's first machine, again using an Orthophonic diaphragm. Whichever one is used, I plan to mount it to the arm of my K8.

I just got done forming a 3-foot recording horn using galvanized duct work sheeting and pop rivets. It's surprisingly efficient.