I got a 78rpm metal master, now what?

[Johndoe64]

Exactly what the title says! Today, I acquired this original Brunswick master. It is matrix E-27953, "The Two Lives" by Frank and James McCravy, 1928. It's very dirty, pretty warped, and there's some corrosion on the surface outside of the play area. So what now? What's the best way to clean a master? What, if anything, do I do with the corrosion? What is the safest way to flatten the warp? Is there a way to press a new record from it, like what the Bear family did with the carter family masters, or should I try making a resin copy like Don Wilson? Any advice would be appreciated. Thank you!

[recordmaker]

This looks like it has a groove like a record but that might be the lighting it could be a master a mother or a stamper the test groove on the edge and the untidy center hole suggests a master or a mother. I assume it is thin as well in that case. ( most 1928 stampers would have a thick back but it could have been unsoldered I suppose )
Cathodic electrolytic cleaning is best but a little difficult to set up for a larger object like that.

Can you show the back of it as well ?
And confirm the indented groove or raised negative groove.

[edisonplayer]

What is especially nice if the stamper you have is one for an unissued recording. edisonplayer.

[Johndoe64]

This looks like it has a groove like a record but that might be the lighting it could be a master a mother or a stamper the test groove on the edge and the untidy center hole suggests a master or a mother. I assume it is thin as well in that case. ( most 1928 stampers would have a thick back but it could have been unsoldered I suppose )
Cathodic electrolytic cleaning is best but a little difficult to set up for a larger object like that.

Can you show the back of it as well ?
And confirm the indented groove or raised negative groove.

Here are some more pictures. They are raised negative grooves. I've held an original stamper before, that one had a smooth copper plate backing that was soldered onto the negative, not a rough surface like this one. This is also quite a bit thinner than a stamper. And it's stamped "Master", so that was the final giveaway. According to DAHR, this side was indeed issued, it would be interesting to find one in the future that was unissued!

The stamper that I'd mentioned handling, I'll hopefully be picking that up this Saturday. I couldn't find a match to the matrix on that one, so that may or may not have been issued. I'm located near Muskegon MI, where Brunswick was headquartered, and I've been scouring the area for more original metal parts, so hopefully more will come to the surface.

Thank you for the suggestion of Cathode Electrolytic cleaning, I will see if there is a place I can take this to have it cleaned!

[recordmaker]

the extra pictures are great.
The master was often most flimsy of the stages and the mother mold was the only one that was handled to make stampers. I assume the back is copper and there would have been a thin protective nickle plating over the front as shown. As you note the rear of a master (and a mother) has no need to be smooth as it is only used for metal to metal copying of the music surface.
any flattening process risks the nodular back surface dimpling the front .
A metal to resin copy process is possible but needs the right release agent and a suitable jig to seal the center and the dam the edge to form a disc.
I have seen a process using white wood glue ( PVA adhesive) that might yield copy that could be played on a turntable with a light weight pick up.
a silicone molding would not stick but would be a bit soft to play I think.

[Johndoe64]

the extra pictures are great.
The master was often most flimsy of the stages and the mother mold was the only one that was handled to make stampers. I assume the back is copper and there would have been a thin protective nickle plating over the front as shown. As you note the rear of a master (and a mother) has no need to be smooth as it is only used for metal to metal copying of the music surface.
any flattening process risks the nodular back surface dimpling the front .
A metal to resin copy process is possible but needs the right release agent and a suitable jig to seal the center and the dam the edge to form a disc.
I have seen a process using white wood glue ( PVA adhesive) that might yield copy that could be played on a turntable with a light weight pick up.
a silicone molding would not stick but would be a bit soft to play I think.

Interesting, I'll have to give it a try! I'll experiment with the stamper when I pick it up, I'd like to minimize my handling of the master. It doesn't show well in these pictures, but the master is seriously warped, and any resin copy made from how it is now would never track at 78rpm. It would be tough to track at 33rpm even, it's pretty bad. But if there's no way to undo that warp without risk of damage, I'd just as soon leave it as is, and if someone comes up with a better way in the future let them take a crack at it.

[Johndoe64]

Got that stamper today too. Matrix is L-152-A, couldn't find a match for that online. Anyway, very different from the master.

[recordmaker]

very nice

looks like an unbacked stamper in one layer of cooper with possibly a chrome face? that would put it later than 1930 when the chrome plating process became practical. however I judge that but the bluish tinge on the metal and that could be a photographic artifact.
The recording looks loud and also suggests a later recording as does the mounting method.
It also looks like and eccentric groove at the end.

[AmberolaAndy]

Let’s hope there were smart people who worked for the Wisconsin Chair Factory that didn’t share their fellow Co-workers short-sightedness!!!

[gramophone-georg]

very nice

looks like an unbacked stamper in one layer of cooper with possibly a chrome face? that would put it later than 1930 when the chrome plating process became practical. however I judge that but the bluish tinge on the metal and that could be a photographic artifact.
The recording looks loud and also suggests a later recording as does the mounting method.
It also looks like and eccentric groove at the end.

There is also a lead- in groove.