Thank you Herb! It sounds like the black foamed plastics or those pink foamed plastics in a proper storage crate/box are the way to go... except consider replacing them every 5-10 years maybe rather than leaving them there 'forever'.. The tubes also work - though you need the right size tubes, and I guess you can cut them to size to store in smaller containers.. That's my take-away from this :) On Tue, Dec 17, 2019 at 12:18 PM Herb Johnson via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:

Henry S. Courbis (and others) suggest "antistatic foam is better than nothing" and suggests sealed antistatic bags to store the antistat'ed ICs. Also suggested are antistatic IC tubes, which Bill Degnan correctly states are superior. But many people (including Henry, myself) end up, piling chips in black anti-stat foam "in a shoebox", as he posts.

I'm not ragging on Henry; everyone has these problems and uses the solutions reasonably available. Or we inherit collections of chips stored this way. Due to my age it's clear to me, these are serious problems over a few decades. Since many vintage computers and components are 40, 50 or more years old, it's a more serious problem for those things.

Some science and engineering of materials comes into play when dealing with old IC's and their storage. If such discussions are not of interest, stop reading here.

http://www.retrotechnology.com/restore/res_ithaca.html

I don't have a specific Web page, about problems with "black rust" AKA "silver oxide". But many have observed that certain TI (Texas Instrument) IC's from the 1980's 90's have had IC pins turn black and become brittle. In sockets these IC's must be replaced; soldered in they seem to mostly perform OK (until they don't). Other ICs in general may suffer similar brittle-rust-pin problems. I don't have a factual scientific finding on the chemistry of the problem But there's no doubt problems occur for certain runs, brands, and eras of IC's.

Solutions to the old chips that rust-out? one simply avoids them. They now stand out with their black and sometimes brittle "legs". My expedient (described on the Web page cited) was to use De-Oxit per pin and socket and pray.

Antistatic-plastic tubes are available and not overly expensive in bulk. One accumulates these or just buys them. Replacement every few decades is simply a fact, because they *break up* otherwise. Other than the tube's decay, I'm not aware they cause other problems.

I and others have seen chips, stored for decades in antistatic foam, fall apart when pulled out. We have all seen such foam become dust or mud. So, it's a problem. I'll detail what I know.

I did some research several years ago about the nature of black antistatic foam. I had to recover chips stored since the 1970's in black foam in a cardboard box; others were packaged in individual little hard-plastic containers, also with black foam.

The classic conductive material in these foams, appears to be carbon-black. Some carbon-black is produced by burning (with acids I believe) *sugar*. Consequently, some resulting carbon black contains sugar and acid. Over time and in the presence of oxygen and moisture, these contribute to *corrosion*. And over decades, the base material of anti-static "foam" degrades, as does almost any plastic. When these anti-static foams are cheaply produced, these problems seem to occur sooner.

Antistatic foam is intended to be a temporary storage, generally, for transport. I'm sure someone with more industrial knowledge, can inform me about long-term storage methods. I'm generally aware, those involve sealed plastic and antistatic or conductive baggies. There's likely other and better (or worse) materials used in storage in recent years.

Among the decades-old ICS, I observed there was much less damage among the individual containers than in the "black foam in a box" items. I hypothesize that the somewhat sealed containers reduced oxygen and moisture exposure. I left those items alone.

The chips stored in sheets of crumbling black foam? As an expedient, I repackaged them in "aluminum wool" sheets and sealed anti-stat bags. "aluminum wool" is like steel wool, only made from aluminum. It was awful, cheaply made, crumbly stuff. But it wont' rust or induce rust in other metals, and it provides conductive protection. Instead of 'cardboard boxes" I used acid-free archival boxes. Most cardboard is full of acids, from the paper-making process. Again - these choices were an expedient of time and cost.

I didn't and don't have cheap solutions to these "black-foam" problems; but I've not looked lately. I'm glad the subject came up for discussion (if anyone has read this far).

I don't know of a better and relatively cheap material to use as an antistatic embedded "pad", than the black (and pink) foamed plastics in current use. It seems prudent to replace the foam every several years, and to sealed-bag such things: yet I don't follow my own advice out of convenience. Conductive tubes are reasonable for batches of like chips; inconvenient for individual chips.

IF somone has factual/engineering data about some modern material alternatives, I'd love to hear about it. Don't forget the material facts.

Regards, Herb Johnson

-- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT retrotechnology DOT info