sodium_stearate
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Making Edison Cylinder Records
Greetings! So glad to have found this board!
Two years ago, I got back into a life-long project of mine that
involves an Edison cylinder phonograph from 1906. Many years
ago I fully restored that machine to full working condition.
It can record as well as play. Got the recorder working and
used some Dictaphone blank cylinders to record on. All working
well.
Along with that, about 20 years ago I started making a mold to
cast the wax blank cylinders myself. That mold sat unfinished
until two summers ago. Finally finished it, and then went about
making a few cylinder castings in it using old broken records
remelted and cast. Got that working ok.
Now for the chemistry: Along with my research done years ago, I found a recipe for the "wax" used to originally cast
those blanks. It is called "brown wax", but it's really a
metallic soap.
Ingredients: stearic acid, sodium hydroxide, aluminum,
ceresin wax, distilled water. The procedure is basically
saponification (soap making), with some added twists.
I know some little chemistry, but had to work fairly hard to
get this procedure working right. The finished "wax" is
basically sodium stearate with about .25% aluminum.
The ceresin wax is then added to about 18.4 % by weight.
I first take 16 fl oz distilled water and dissolve in 32.4 grams
of sodium hydroxide. Once that's all dissolved in, then I
add 1.07 grams of aluminum (foil) and let that dissolve in.
Then, the liquid gets filtered through multiple coffee filters
until perfectly clear and set aside.
Then, in an old 6 cup percolater coffee pot I melt up 212 grams
of stearic acid. and heat it to 190 C. The sodium hydroxide
solution previously made then gets slowly added to the melted
stearic, about 1 fl oz at a time. It boils up and forms a precipitate which slowly cooks in. When the temp gets back up
to around 190 C again, then some more lye solution is
added, and the process is repeated.
The total amount of lye solution that makes good wax is about
11 fl oz of the original 16 fl oz made. A typical batch takes about 90 minutes and about 16 of those additions, to get all
11 oz of the lye/water/aluminum into the melted stearic.
By that time, the stearic is turning brown and it's roughly
50 % saponified. Along the way to get that far, sometimes temps of 260 to 270 C are necessary to get the precip all dissolved in. Once this stage
is reached, then an additional
amount of 70.6 grams stearic acid are added, and stirred
in. Then the whole is cooked at 232 C for 10 minutes to
assure complete combining. At this point it's about 50%
saponified, and it's a very runny dark liquid.
To this then is added 63.6 grams of ceresin wax. This then
gets all melted in and stirred, then cooked for another 10 min.
at 232 C.
It is then taken off of the heat, and a small sample is spooned
off into a small foil container. The sample is about 1.5 inches
in diameter and maybe a quarter inch thick. After about
half and hour, the sample is broken, and the inside is
examined for defects. If it is homogenous all the way through
and has no separation, or streaks or other troubles, it is
ready for casting in the mold.
If the sample has any defects, these can be worked out by
remelting and adding some small amount of stearic acid
usually. (in rare cases it needs another dash of the lye/water)
This is from an 1896 recipe used at Edison's lab to make
those brown wax cylinders. I had to dust off my chemistry
knowledge (what little of it there is) in order to get this
formula working. Did lots of experiments to get this far.
One of these batches casts about 2.5 records. So, the leftover
amounts from ends of batches get melted together and soon
there is enough for another record.
Have cast 102 of them so far, and at least 70 of them are
nice quiet records with very low surface noise and they all
take recording quite well.
I really need better ventillation though. Even out in a garage
with big fans and open windows and doors, it's bad.
That saponification reaction gives off some very nasty fumes.
Lots of smoke too when temp gets around 250 to 270C
It will catch on fire too, but not in the coffee pot as that is
tall and narrow enough to keep it from igniting.
Now I will get to hear from you real chemists out there to
see what your impression of this crude process is!!
I am using a small one-burner Coleman gasoline camp stove
to heat it with. Found a genuine old glass lab thermometer
too, and use that. Typical total time for a batch is 2 hours, 20 min.
Thanks for reading! 
"Opportunity is missed by most people
because it is dressed in overalls and it
looks like work" T.A. Edison
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Magpie
lab constructor
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Very nice! I like to read about Edison and have read three books so far. My favorite is "Thomas Edison, Chemist," by Vanderbilt.
Just recently I visited Edison's laboratory at West Orange, NJ. It is now a museum managed by the National Park Service and is open to the public.
One of the stories that amazed me was that he started making his own phenol due to WWI taking all the domestic supplies for the purpose of making
picric acid. In 2 months Edison had designed and built a phenol plant that was making 1 ton/day!
Sorry I can't give you any insights into your "wax" making process, but it sounds like you have it well under control. Edison used phenol to make
phenol formaldehyde resin which was used to make phonograph records if I recall correctly. This could be your next Edison phonograph/chemistry
project!
[Edited on 23-4-2011 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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sodium_stearate
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Magpie,
Yes, I too have read many books about Thomas Edison.
Most recently I read a fairly new one titled "Inventing the
Century", which is a very good read!
And yes, the story about his phenol plant is just one of many
that show what an industrial genius Edison was.
The phenolic resin was used on his later "Diamond Disk"
records. Those came out in about 1912 or so. They are
about a quarter-inch thick, and look basically like a regular
78 rpm phonograph record. The big difference with Edison's
disk records though was that they were recorded "hill and dale" (modulated vertically) instead of the typical horizontal
modulation used on most other disk recordings.
Edison's "Diamond Disk" records played at 80 rpm too, instead
of the more common 78 rpm. In all of Edison's commercial
phonographs, he was way ahead of his time technologically.
Even going clear back to 1889 with his first office-style
dictation cylinder phonographs, Edison always used a
permanent polished sapphire stylus to record and another
shape of that jewel to play back.
Meanwhile, the scratchy, harsh 78 rpm disks were played
using a one-time only steel needle, which was intended to
be changed for every play!
Indeed, looking at a typical Edison cylinder phonograph
playback sapphire stylus now, (well over 100 years later)
one typically sees some minor wear. But, that is not a problem
because those jewels can be removed and re-installed
having been rotated 120 degrees to expose a brand new
polished surface! So...Edison made sure back then that each
and every playback stylus could easily be renewed every
100 years or so, (twice) as needed. 300 year life.
My 1906 machine already had it's playback stylus rotated
once already, back in about 1978 or so.
That stylus will last until at least year 2206! Here it is
100 years after having been made, and it's only barely into
it's 2nd surface...
"Opportunity is missed by most people
because it is dressed in overalls and it
looks like work" T.A. Edison
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sodium_stearate
Hazard to Others
Posts: 255
Registered: 22-4-2011
Location: guard duty at the checkpoint
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Help with improving the process
Hello Again,
It's been a few years since I posted the text description of
my waxmaking process which I use to produce the
Edison cylinder recording blanks.
Since that time, I've made a video which shows the
process. Here's the link
http://youtu.be/LrR9h9fu324
By reading my original post and then watching
the video, you can get some idea what I'm doing.
As you can see, as the caustic solution gets added
portionwise to the melted stearic, there is lots of
steam, which condenses to water vapor. In with this
vapor, is also a significant amount of stearic which
boils off. In short, this open process ends up loosing
some of the end product. The stearic vapor ends
up condensing on the boxfan blades that I use to vent
the area to the outside.
Here is my question for everyone here:
I am thinking of trying to use a much more sealed process
so as not to loose so much stearic to vapor.
One part of this must be some way to condense the
stearic vapor and also some way to separate it out
from the steam and water vapor, and then return the
stearic to the main vessel.
The water must be allowed to escape, but the stearic
must be retained.
I have some foggy ideas about designing some sort
of a condensor/separator which would do that.
So far, about the only real idea which keeps on coming
into my mind would be sort of a long, tall inverted
funnel that would condense the brown partially saponified
stearic out of the steam/water-vapor cloud, and allow
the stearic to run back down into the vessel as droplets
on the inside of the funnel.
This of course would never capture back anywhere near
100% of the lost stearic, but it would recover some of it.
Any ideas? I need to know what sort of things are out there
as surplus gear which maybe could be used.
Thanks for kicking this around!
Chuck
"Opportunity is missed by most people
because it is dressed in overalls and it
looks like work" T.A. Edison
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