Jan,
A few years ago I borrowed some software CDs (~25) from a friend so that I
could rebuild an old VAX system. He said that I might not be able to read all
of them successfully but if I wiped the surface with methylated spirits they
would probably be ok. Anyhow, I gave it a try and ~5 CDs failed to read
initially but after a wipe over with methylated spirits they worked ok. I
assume that the methylated spirits removed some sort of scum from the surface
which affected the optical properties of the surface, maybe something either
from the CD itself of perhaps the plastic sleeves they were stored in.
If you haven't yet disposed of the faulty CDs it might be worth trying to give
them a bit of a clean.
...Wayne
-----Original Message-----
From: olympus
[mailto:olympus-bounces+wayne.harridge=structuregraphs.com@xxxxxxxxxxxxxxxxx]
On Behalf Of Jan Steinman
Sent: Friday, 15 December 2017 7:37 AM
To: olympus@xxxxxxxxxxxxxxxxx
Subject: [OM] Data on Burnable CD Lifetime [was: IMG: Testing times]
> From: Jan Steinman <Jan@xxxxxxxxxxxxxx>
>
> I?m currently crawling through stacks of CDs I?ve burned, trying to recover
> hi-rez scans. About a third of them were put on very cheap CDs, 80% of which
> will no longer read.
Perhaps an interesting data point, perhaps not, to those ungulates who are
profoundly disinterested in optical media� :-)
I�ve now gone through about 250 CD-ROMs. These contained a mix of brand-name
blanks (Memorex, Verbatim), branded bargain blanks, and un-branded, un-coated,
no-name blanks. 250 of these were in three original holders of about 50 each,
with a latching plastic cover. The other 100 were stored on a long plastic
spindle, with plastic base and top, but basically open to the atmosphere. (This
was the way the cheapest, non-labeled disks were bundled for retail.)
Almost all of them with a label, whether a well-known brand or not, worked
fine. These were mixed fairly evenly among the different holders with the
non-labeled, no-name ones.
Of the non-labeled, no-name disks, over 90% of the ones enclosed in clear
plastic cases FAILED, whereas all but one of them that were on the spindle READ
JUST FINE!
Of course, this was not a controlled experiment. They were in an enclosed
cabinet, but perhaps the spindle was closer to the back and farther from
occasional light. Who knows what other variables might have worked in favour of
the spindled ones.
But if you�re storing CD-ROMs, particularly if they are cheap ones without a
top coating, perhaps you want to expose them to the atmosphere, rather than
shield them in clear plastic cases. :-)
No worries. I�ve now got my Frakenbellows working, and I�ll review the PAPER
index sheets of the missing photos for the best, and shoot 50 megapixel images
of the Kodachromes. (The non-Kodachrome film has all faded quite a bit.) I�m
also looking forward to �scanning� my Velvia 4�x5� film in such a manner.
:::: The factory farm results from the absence of moral or regulatory
restraint. -- Ron Schmid <http://www.lmgtfy.com/?q=Ron+Schmid>
:::: Jan Steinman, EcoReality Co-op <http://www.ecoreality.org/> ::::
--
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