LGP-30 Memory Drum Update

Al Kossow aek at bitsavers.org
Wed Jan 4 09:19:40 CST 2017

On 1/4/17 7:03 AM, Klemens Krause wrote:

> We have a second LGP-30 drum in our museum. It is damaged by water.
> (large rusted areas, probably from water between heads and drum).
> I'm dreaming to wash the brown oxide coating off with a solvent like
> acetone, polish the drum and repaint it.
> As magnetic paint I would try iron oxide from audio tapes solved in acetone or some other solvent.
> Perhaps one could ask an airbrush artist to do this.
> Rumours say, that the drums originally also were coated "by hand".

In doing some disk research recently, I came across a footnote for a rather unlikely
place to find information on magnetic coatings, which I just got a copy of:

Patton "Pigment Handbook Volume II Applications and Markets"  1973

Kurt Kreiselmaier "Pigmentation of Magnetic Tapes" pp 315-329

Which goes through the whole process at a high level of how magnetic tape is made,
including aligning all the magnetic particles on the surface. They also mention sperm
oil being used as one of the ingredients (I had wondered if there was documentation
for that claim), and about two dozen patents at the end.

There is also a lot of information in the book on colorizing agents for plastics.

I'll put a scan up today under midwesternUniveristy, where Kreiselmaier was an asst prof.

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