Shelf life

I'm wondering about the relationship, if any, between the two different
"shelf life" aspects of CDR. One is the shelf life of unburned disks, the
other is the shelf life of burned disks. Say unburned disks are viable
for 5 years, and a burned disk is viable for 5 years. If you burn a disk
that has been sitting around for 5 years can you then expect the disk to
be good for another 5 years, or did the clock start running the day you
bought the disk? I guess another way of asking the question is: if a
burned disk becomes useless due to dye degradation, does the burned,
opaque part become transparent, or does the unburned, transparent part
become opaque? And is the dye itself likely to be the failure point?

--
N

.. --------------------------------------
Mike Richter, were you born with
"Scam Artist" emblazoned on your face?
--------------------------------------

Noik wrote:

I'm wondering about the relationship, if any, between the two different
"shelf life" aspects of CDR. One is the shelf life of unburned disks, the
other is the shelf life of burned disks. Say unburned disks are viable
for 5 years, and a burned disk is viable for 5 years. If you burn a disk
that has been sitting around for 5 years can you then expect the disk to
be good for another 5 years, or did the clock start running the day you
bought the disk? I guess another way of asking the question is: if a
burned disk becomes useless due to dye degradation, does the burned,
opaque part become transparent, or does the unburned, transparent part
become opaque? And is the dye itself likely to be the failure point?

The shelf life means a disk is writable after sitting around usually for
5-10 years. The generally stated archival life of 100 yrs means the
burned part is readable for that length of time. But the archival life
does not say anything about writability for parts not burned, however.
Guess is that the shelf life applies to the unburned part.

The relationship between shelf and archival lives gets interesting with
CD-RW. One poster mentioned that once burned cd-rw shelf life
(writability) gets extended to that of cd-rw's archival life of 50 yrs.
This is a big question mark as you asked. Does archival life of cdrw
imply writability also? I haven't come across any article discussing
this aspect.
..

=============================================
Mike Richter - The Slimiest Friggin SOB (UDF)
=============================================

The slimiest friggin SOB Mike Richter has been for YEARS
blaming the UDF to weasel out the bugs of DirectCD:

------------------------------------------
UDF is a fragile format
UDF is an unreliable format

the format is very fragile and unreliable

The format is bad - it loses data

The fault is not with the software but with the format

I have used only DCD for packet writing,
have had no problems due to the software
- but too many due to the format itself

to bother with it any longer.
------------------------------------------

But then again:

======================
From: Mike Richter (The Slimiest Friggin ****)
Date: 5/4/06
Subject: UDF Has just bit me in the bum

I have used UDF for many years, but yesterday I had my first
corruption. I am now wondering whether to bother with UDF

First, your problem is not with UDF
======================

-------------------------------
Wow! What a slimy friggin SOB!
----------------------------------------
Mikey, you are The Slimiest Friggin SOB!
----------------------------------------
Mike Richter, were you born with
"Scam Artist" emblazoned on your face?
--------------------------------------
(Mike Richter, any Material Connection w/ Roxio?)

On Mon, 11 Sep 2006 21:40:50 -0400, Noik wrote:

I'm wondering about the relationship, if any, between the two different
"shelf life" aspects of CDR. One is the shelf life of unburned disks, the
other is the shelf life of burned disks. Say unburned disks are viable
for 5 years, and a burned disk is viable for 5 years. If you burn a disk
that has been sitting around for 5 years can you then expect the disk to
be good for another 5 years, or did the clock start running the day you
bought the disk? I guess another way of asking the question is: if a
burned disk becomes useless due to dye degradation, does the burned,
opaque part become transparent, or does the unburned, transparent part
become opaque? And is the dye itself likely to be the failure point?

I've been gathering data on this for some years now.

I have a set of old disks (Kodak Gold) that, once burned, rarely
lasted more than 2-3 years before becoming unreadable. I also have
some unburned Kodak Gold blanks, still wrapped in the jewel cases
(this is how quality CDRs came back then), and I was troubleshooting a
problem the other day where an old laptop drive was failing to read
any burned CDs, but was OK on pressed media and burned DVDs.

I burned one of these NOS (new old stock) Kodak Golds at 4x, and the
laptop read it just fine. These blanks are probably 6-7 years old at
this point, and the ones I burned from this original batch have long
since gone to the great bit-bucket in the sky.

This tells me that the unburned shelf life of these particular CDRs is
much longer than the burned shelf life, and I'd guess that the clock
on the burned shelf life starts ticking once the disk is burned.

Note that this is a single data point, and it may be a few years
before I know if the burned shelf life on this is better or worse than
when they were fresh, but my confidence is pretty good that this disk
will die within the next few years.

My theory on this is that the definition (ie, edges) of the "pits" of
burned disk data relaxes over time, making the data less and less
readable, rather than the dye changing opacity over time, but I'm
unable to verify this effectively, even with a microscope. I partly
base this on the fact that burning at half the maximum rated burner or
blank speed results in disks that last much longer than ones burned at
full speed. It seems pretty clear to me that the dye is the failure
point.

The sorry thing about this is that the media makers know what the
exact failure mechanism is, and they don't publish any real data on
burned data lifetime that I'm aware of.

FWIW, marketing claims of long disk life are purely speculation, and
should never be believed unless you don't mind losing your data
completely.



--
Neil Maxwell - I don't speak for my employer

On Mon, 11 Sep 2006 23:05:24 -0700, smh wrote:

. --------------------------------------
Mike Richter, were you born with
"Scam Artist" emblazoned on your face?
--------------------------------------

Noik wrote:

I'm wondering about the relationship, if any, between the two different
"shelf life" aspects of CDR. One is the shelf life of unburned disks, the
other is the shelf life of burned disks. Say unburned disks are viable
for 5 years, and a burned disk is viable for 5 years. If you burn a disk
that has been sitting around for 5 years can you then expect the disk to
be good for another 5 years, or did the clock start running the day you
bought the disk? I guess another way of asking the question is: if a
burned disk becomes useless due to dye degradation, does the burned,
opaque part become transparent, or does the unburned, transparent part
become opaque? And is the dye itself likely to be the failure point?

The shelf life means a disk is writable after sitting around usually for
5-10 years. The generally stated archival life of 100 yrs means the
burned part is readable for that length of time. But the archival life
does not say anything about writability for parts not burned, however.
Guess is that the shelf life applies to the unburned part.

Well, if that 100 year number is accurate, my question is moot. ;-)
I see I made a hash of asking the question, whoops. Maybe the best way
to sort things out would be to talk about how I used the terms
burned/unburned in different ways. In general, unburned would refer to
the part of a disk that didn't have any data stored on it, but I also
referred to the data portion of a disk that didn't get hit by the laser.
Whether those bits in the data part that didn't get hit by the laser
remained transparent or not would be a factor in the archival life of the
disk.

The relationship between shelf and archival lives gets interesting with
CD-RW. One poster mentioned that once burned cd-rw shelf life
(writability) gets extended to that of cd-rw's archival life of 50 yrs.
This is a big question mark as you asked. Does archival life of cdrw
imply writability also? I haven't come across any article discussing
this aspect.

That doesn't sound right. I'd think that the "unburned" parts of the
data section would have the same properties as the virgin disk.

--
N

On Wed, 13 Sep 2006 08:47:11 -0700, Neil Maxwell
wrote:

I've been gathering data on this for some years now.

I have a set of old disks (Kodak Gold) that, once burned, rarely
lasted more than 2-3 years before becoming unreadable. I also have
some unburned Kodak Gold blanks, still wrapped in the jewel cases
(this is how quality CDRs came back then), and I was troubleshooting a
problem the other day where an old laptop drive was failing to read
any burned CDs, but was OK on pressed media and burned DVDs.

I burned one of these NOS (new old stock) Kodak Golds at 4x, and the
laptop read it just fine. These blanks are probably 6-7 years old at
this point, and the ones I burned from this original batch have long
since gone to the great bit-bucket in the sky.

This tells me that the unburned shelf life of these particular CDRs is
much longer than the burned shelf life, and I'd guess that the clock
on the burned shelf life starts ticking once the disk is burned.

Did you check the error rates of those disks? How old were they when
you burned them? It could maybe be that those old disks were barely
viable and yielded a very low quality burn with high error rates that
were on the edge of being readable, and a few years of "normal"
degradation put them over the edge.
I seem to remember reading that Kodak Gold were pretty crappy disks,
but I could be wrong about that. What type of dye do they use?

Thanks for the info.

--
N

On Thu, 14 Sep 2006 22:55:36 -0400, Noik wrote:

I seem to remember reading that Kodak Gold were pretty crappy disks,
but I could be wrong about that. What type of dye do they use?

Thanks for the info.

The "new" Kodak discs that are currently being sold aren't getting
good reviews (haven't tried them myself yet). The older Kodak
"Digital Science" Gold, and Kodak "Ultima" Gold, Gold+Silver, and
Silver were considered excellent media. Back in the day, the three
top names for quality media were Kodak, Taiyo Yuden, and Verbatim,
with TY being considerably harder to get back then. Sadly, with all
the low priced competition, Kodak decided that those discs were just
too expensive to produce, so they exited the market.

Both the original and current production Kodak discs use some
variation on the Pthalocyanine recipe as the dye type. I don't think
the dye is the original formulation though, as they no longer tout
Gold or Silver components for their reflective layer, and the new
discs are rated for modern speeds. The DS discs were only rated up to
6x, and the Ultimas only officially went up to 12x, according to the
jewel cases on mine.
---------------------------------------------
Thanks.


MCheu

On Fri, 15 Sep 2006 11:50:44 -0400, MCheu wrote:

| The "new" Kodak discs that are currently being sold aren't getting
| good reviews (haven't tried them myself yet). The older Kodak
| "Digital Science" Gold, and Kodak "Ultima" Gold, Gold+Silver, and
| Silver were considered excellent media. Back in the day, the three
| top names for quality media were Kodak, Taiyo Yuden, and Verbatim,
| with TY being considerably harder to get back then. Sadly, with all
| the low priced competition, Kodak decided that those discs were just
| too expensive to produce, so they exited the market.

Kodak isn't the only one of the original top three having problems. Verbatims
aren't nearly as dependable now as they were only a short time back. With much
of their production farmed out to such "ordinary" disc manufacturers as CMC
Magnetics and Prodisc, Verbatim's quality is slipping noticeably.

Larc



§§§ - Change planet to earth to reply by email - §§§

On Thu, 14 Sep 2006 22:55:36 -0400, Noik wrote:

Did you check the error rates of those disks? How old were they when
you burned them? It could maybe be that those old disks were barely
viable and yielded a very low quality burn with high error rates that
were on the edge of being readable, and a few years of "normal"
degradation put them over the edge.
I seem to remember reading that Kodak Gold were pretty crappy disks,
but I could be wrong about that. What type of dye do they use?

They were pretty much new, as CDRs were pretty expensive back then,
and buying hundreds at a time was a big investment. I mostly only
used CDRs considered high quality by 'net consensus, such as Mitsui,
KAO, and Kodak.

I saw these early failures on many kinds of disks, burned on many
different burners, including Plextor (still called Texel when I got my
first one).

The only ones I've gotten good lifetimes reliably on so far have been
TY, burned at half speed. I haven't used anything else for years, so
I don't have much longevity data on newer formulas and brands.

max

On Fri, 15 Sep 2006 11:50:44 -0400, MCheu wrote:

On Thu, 14 Sep 2006 22:55:36 -0400, Noik wrote:

I seem to remember reading that Kodak Gold were pretty crappy disks,
but I could be wrong about that. What type of dye do they use?

Thanks for the info.

The "new" Kodak discs that are currently being sold aren't getting
good reviews (haven't tried them myself yet). The older Kodak
"Digital Science" Gold, and Kodak "Ultima" Gold, Gold+Silver, and
Silver were considered excellent media. Back in the day, the three
top names for quality media were Kodak, Taiyo Yuden, and Verbatim,
with TY being considerably harder to get back then. Sadly, with all
the low priced competition, Kodak decided that those discs were just
too expensive to produce, so they exited the market.

I used a mix of Gold, Silver, and Ultima, as quality disks were
important to me. All of these Kodaks have a 100% failure rate over 5
years. Mitsui and KAO were also considered high-quality media, back
in the 4x days.

Looking back on it, there was no actual data to support the claims of
these CDRs having long life - it was all "tribal knowledge" on the
'net.

Since mine started failing, I've gathered quite a lot of data on CDR
failures, both initial and long-term. The only one I've had good luck
with, as I said in another post, are TY burned at half speed (and I
had a bad batch of them a little while back).

The fact is, burned media is unreliable over the long term. There's
no long-term data on current dyes and reflective layers, as they
change constantly to meet the market needs and cost pressures. My TY
data is very strong (to me, at least), but I'm not going to assume my
5 year old disks that have survived are the same as the ones I burn
today.

Both the original and current production Kodak discs use some
variation on the Pthalocyanine recipe as the dye type. I don't think
the dye is the original formulation though, as they no longer tout
Gold or Silver components for their reflective layer, and the new
discs are rated for modern speeds. The DS discs were only rated up to
6x, and the Ultimas only officially went up to 12x, according to the
jewel cases on mine.

I wouldn't be surprised if Kodak buys from OEMs now, rather than
making their own, but I don't know.

The last few Ultima jewel case blanks I have are labeled 8x. That's
about when I switched over to TY.

YMMV, as always!

max

.. --------------------------------------
Mike Richter, were you born with
"Scam Artist" emblazoned on your face?
--------------------------------------

Noik wrote:
smh wrote:
Noik wrote:

I'm wondering about the relationship, if any, between the two different
"shelf life" aspects of CDR. One is the shelf life of unburned disks, the
other is the shelf life of burned disks. Say unburned disks are viable
for 5 years, and a burned disk is viable for 5 years. If you burn a disk
that has been sitting around for 5 years can you then expect the disk to
be good for another 5 years, or did the clock start running the day you
bought the disk? I guess another way of asking the question is: if a
burned disk becomes useless due to dye degradation, does the burned,
opaque part become transparent, or does the unburned, transparent part
become opaque? And is the dye itself likely to be the failure point?

The shelf life means a disk is writable after sitting around usually for
5-10 years. The generally stated [CLAIMED] archival life of 100 yrs means
the burned part is readable for that length of time. But the archival life
does not say anything about writability for parts not burned, however.
Guess is that the shelf life applies to the unburned part.

Well, if that 100 year number is accurate, my question is moot. ;-)
I see I made a hash of asking the question, whoops. Maybe the best way
to sort things out would be to talk about how I used the terms
burned/unburned in different ways. In general, unburned would refer to
the part of a disk that didn't have any data stored on it, but I also
referred to the data portion of a disk that didn't get hit by the laser.
Whether those bits in the data part that didn't get hit by the laser
remained transparent or not would be a factor in the archival life of the
disk.

When a track is burned, the laser is ON throughout the track. For
example, you do burn a "neutral" character like 0x00. There is no
unburned part in a track. My unburned part refers to the outer area of
disc where no track is burned.


The relationship between shelf and archival lives gets interesting with
CD-RW. One poster mentioned that once burned cd-rw shelf life
(writability) gets extended to that of cd-rw's archival life of 50 yrs.
This is a big question mark as you asked. Does archival life of cdrw
imply writability also? I haven't come across any article discussing
this aspect.

That doesn't sound right. I'd think that the "unburned" parts of the
data section would have the same properties as the virgin disk.

Again, there is no unburned parts in a track.
..

=============================================
Mike Richter - The Slimiest Friggin SOB (UDF)
=============================================

The slimiest friggin SOB Mike Richter has been for YEARS
blaming the UDF to weasel out the bugs of DirectCD:

------------------------------------------
UDF is a fragile format
UDF is an unreliable format

the format is very fragile and unreliable
The format is bad - it loses data
The fault is not with the software but with the format

I have used only DCD for packet writing,
have had no problems due to the software
- but too many due to the format itself

to bother with it any longer.
------------------------------------------

But then again:

======================
From: Mike Richter (The Slimiest Friggin ****)
Date: 5/4/06
Subject: UDF Has just bit me in the bum

I have used UDF for many years, but yesterday I had my first
corruption. I am now wondering whether to bother with UDF

First, your problem is not with UDF
======================

-------------------------------
Wow! What a slimy friggin SOB!
----------------------------------------
Mikey, you are The Slimiest Friggin SOB!
----------------------------------------
Mike Richter, were you born with
"Scam Artist" emblazoned on your face?
--------------------------------------
(Mike Richter, any Material Connection w/ Roxio?)