The Talking Machine Forum — For All Antique Phonographs & Recordings

Which is better?
Are the brown records softer than the black ones?

The hardness / softness depends on the overall composition of the record. Shellac is just the base material.

Black 78 records are that way because they used a coloring agent to make them that way, and brown ones as well. Modern vinyl records are also "colored" black. Unless they're not black.

Shellac can range anywhere from a light gold to a dark red as a raw material (excretions from the lac bug). Colorants and other various materials are added to this to make records. There are also Blue, Yellow, Red, and even multi-color records around, though black is the most common. Softness, as Wolfe stated, would really depend more on the composition overall, and not the colorant.

The only record in my smallish collection that isn't black is a Perfect label red one. I've heard it said that the black color may be anthracite coal fines added to the various "shellac" formulae used by the different labels. Interesting, because anthracite is almost pure carbon, and should therefore impart a lubricating quality to the record surface (think graphite). Any thoughts on this?

Henry wrote: Interesting, because anthracite is almost pure carbon, and should therefore impart a lubricating quality to the record surface (think graphite). Any thoughts on this?

Well, diamond is also carbon - but one wouldn't use it as a lubricant.

The slipperiness of graphite is due to the way the carbon atoms are arranged vs. anthracite…


Bill

From my distant past as the chemist in a rubber factory - carbon black is both a pigment, and in larger proportions a structural filler, which increases hardness and other physical properties. Depending on type, the particles can be quite abrasive too (e.g. furnace black - whereas lampblack is softer and fluffier).

Does anyone have information on shellac formulations for records? It would be interesting to see how much carbon black was used, although it probably varied widely.

Brown is better because you can pick them easier from all the black ones!

Does anyone have information on shellac formulations for records? It would be interesting to see how much carbon black was used, although it probably varied widely.

On a serious note, Orchorsol - have you seen my video link in topic under Music "How a 78 is made?" It's video footage from 1942 of how shellac records are made. I was amazed at how many different processes are carried out to get to a final shellac record, which is ready for being recording onto. I think you might find it interesting. It's worth a watch.

Just found this on Google which might be what you're looking for?

Shellac 13.5%

White filler (powdered Indiana limestone) 37.5%

Red filler (powdered Pennsylvania slate) 37.5%

Vinsol (a plastic with a low melting point) 8.5%

Congo Gum (a flexible binder) 1%

Carbon Black (colorant) 1.5%

Zinc stearate (lubricant for mould release) 0.5%
Flake shellac 15.63%

Congo Gum 6.51%

Vinsol Resin 5.86%

Carbon Black 2.61%

Zinc stearate 0.32%

Whiting (CaCO3) 52.13%)

Aluminium Silicate 13.03%

Flock (long fibre) 3.91%
web site link where above came from = http://www.nwsoundarchive.co.uk/preserv ... discs.aspx)

or the following links may be worth visiting:
http://www.recordcollectorsguild.org/in ... =28&page=6
http://www.patentstorm.us/patents/6620431.html

I'm surprised that you found a detailed formula for making the shellac record compound. By the way, the list you have is actually TWO different formulations - the first ending with the 0.5% of zinc stearate which adds up to 100% and those following ingredients also adding up to 100% as is clear from the original article as referenced.

Record companies well into the 1970s were VERY secretive about their compound formulations which were considered company secrets - the ingredients as well as the complex mixing and processing used to make the compound. When I was at RCA Records manufacturing in Indianapolis, we would gladly take just about anyone on a tour of the pressing plant, but NEVER took any guests to see the vinyl compounding area. Which is why very little has been published about record compound formulations. Those formulae that you find are often deliberately wrong to throw off would-be copiers. After about 1980, most US record plants stopped doing their own compounding and bought granulated compound from one of two or three major suppliers. Even then, those suppliers were not eager to share their formulations with the competition.

So I would take any formulae that you find for record compound as an approximation of the real thing. But what you can see from the above formulae is that there was a LOT of mineral filler in the compound. Indiana used to be one of the major record manufacturing states in the USA. Our chief engineer used to claim that that happened because of the prevalence of crushed Indiana limestone used in the compounds back in the shellac days. At first I thought he was joking, but now I think he was actually correct in that claim.

When I was at RCA Records manufacturing in Indianapolis, we would gladly take just about anyone on a tour of the pressing plant, but NEVER took any guests to see the vinyl compounding area.

What an amazing job. I wonder how long ago you worked there?

You can find just about anything on Google these days if you know what to look for

There's an enormous amount you can't find on Google. Especially concerning this hobby.