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Here's another take on mold release

Posted by ecl876 (A) on January 22, 2016 at 12:48:18

In Reply to: Another audiophile myth debunked: Mold Release Compound posted by kentaja on January 22, 2016 at 08:30:50:

This is from Scott at Steve Hoffman's site:

OK, I just got off the phone with Duane Goldman (The Disc Doctor). This guy knows more about the vinyl pressing process than anybody I know. To give you an idea, I had two or three questions that turned into an hour long conversation about vinyl production dating back to the days of shellac.

I have to preface this for those that think this might be a promotion for his products....well it isn't. During the hour long conversation his products didn't come up but twice. This conversation focused on the formulation and the history of vinyl production.

The Rob Doorack post over at AA is likely, quite true. He quoted a statement that Stan Ricker made when he said that Stan had never seen anyone spraying mold release agents onto the stampers at any of the plants he had visited. What wasn't divulged in that post was the fact that mold release agents are part of the formulation in the vinyl. They have been an integral part of the vinyl production process since the days of shellac.

In the early days the mold release agents (salts of stearic acids) were lead, cadmium, and nickel. When awareness came about that these heavy metals were harmful to people (in the early 60's) they changed the formulations to magnesium and potassium. These salts are still in use today as mold release agents. Duane also went on to say that it is literally impossible to press a record without the use of some form of mold release agent. If (and when) they did produce records without the use of release agents, it left the record surface severely pitted and unplayable.

The way the mold release agent works is that it is mixed in with the vinyl pellets along with other fillers, brought to a melting temperature, mixed and then applied to the stampers (that was a very simplistic explanation and no doubt I skipped over a few steps, so don't slam me please). After the record is pressed, there remains a very thin, uniform layer of of this mold release agent that remains on the outermost surface of the vinyl. This agent tends to be a waxy substance when it has cooled. This wax can (and will) deposit a gummy substance on your stylus if it is not removed by cleaning.

The proof there is quite easy to detect. Take a new, uncleaned record and play it a time or two. Take a jewelers loupe and look at your stylus. You'll see black stuff adhering to it. Then clean you record with a solution that removes the mold release agent and repeat the experiment. This time you shouldn't see the black stuff. Somewhere on the web I remember seeing microscopic views pre and post cleaning. The difference was quite obvious.

The rumor that mold release agents were sprayed on has some ring of truth to it. As Duane tells it, back around the time of the oil embargo days, several of the pressing plants experimented with spraying low molecular weight, silicone oils on the stampers to hasten the production process. Thing was, mold release agents were still used in the vinyl formulation. The silicone was used so that the production could be sped up. This allowed the stampers to be separated before the vinyl had properly cooled. This left one side of the vinyl exposed to room temp while the other side laid there on a hot stamper. This led to very poor sounding vinyl (according to Duane). In turn, after this experiment, they stopped using the silicone oils as an additional mold release agent and simply allowed the vinyl to cool down gracefully as it should have. I think this is where the rumor started that mold release was sprayed on.

This post is made possible by the generous support of people like you and our sponsors:

Schiit Audio

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