CDR Media Dye Types

[Namuna]

You've got your Cyanine and PhthaloCyanine and Azo. And basically Cyanine is the De-Facto Dye used by CDR Media Manufacturers (your blue bottom standard ones). PhthaloCyanine is the SLIGHTLY higher end stuff with the Gold in it that's supposed to have a shelf-life of like 100 years. And the Azo is a variation of both.

Alright, so now here's the next thing...What the heck do they mean by 'TYPE #'?

Cyanine Type:0
Cyanine Type:1
PhthaloCyanine Type:6
and so on...

http://www.cdmediaworld.com/hardware/cdrom/cd_dye.shtml has been the best place to get info on the Dye, but I still can't find out more about the 'Type #'. Anyone have more info?

Thanks!

 

[Mark R]

The 'Dye type' numbers don't give any hard information as to the forumlation of the disc - so don't read too much into them.

They are used by the recorder as a guide to the 'write strategy' - laser power, pulse length and other factors. For example, pthalocyanine dyes work best when recorded with high-power, short laser pulses, whereas cyanines are better with lower-power longer pulses. Metal-azo dyes use the same strategy as cyanine, and usually are type 0.

There are a number of different dye types recognised by modern writers, even for seemingly similar forumlations, hence type 0, 1 and 2 are all usually cyanines - not all cyanine, and other types, of dyes are the same, and there may even be variation between batches of a dye. The disc manufacturer will usually set the write stategy to that which has been found to give best performance during pre-production tests.

Finally, a minor point - pthalocyanine doesn't have gold in it. It just looks gold when combined with a silver reflective layer. It's actually a very pale green. Pthalocyanine is extremely light stable, and should therefore have a longer shelf life than cyanine - although I think 100 years is optimistic, unless the discs are manufactured with a real gold reflective layer. Use of gold in CD-Rs has fallen out of fashion, mainly due to cost - a single disc needs about $0.40 of gold! Pthalocyanine does also give better results than cyanine, but with a slight drawback - pthalocyanine requires very accurate laser power level and focus control. If your writer is slightly out of spec then cyanine will give better results.

 

[Namuna]

Ahhhh, some clarification.

Thanks for the info Mark!

 

[randypj]

Mark--Thank you for the info. For my worst case PLAYERS, pthalocyanine seems to present the best chances of playing audio. So, it makes my Plex burn it with a higher power, resulting in better reflectivity? I.E., more differentiation in the burned pits/non-pits?

Also, is this what CloneCD is doing with "laser calibration"....or whatever?
--Randy

 

[Mark R]

It's not quite as simple as that. Reflectivity is dependent on the dye - and pthalocyanine is better. Contrast and quality of 'pit' is dependent on laser power but not in a very simple way. You don't get better reflectivity because the disc is burned at higher power, but because of the formulation of the dye.

Just saying that one dye needs a higher laser power than another is really oversimplifying it somewhat - different dyes also need different pulse lengths and shapes (hence the dye type guide number) because the dye responds differently to heating.

Because recording only works well when the laser power is matched carefully to the dye (much more of a problem with pthalocyanine) recorders will always perform a test burn and read-back on a special area of the disc. It will adjust the laser power until the reading is satisfactory, or until it runs out of space (at which point you have a coaster). This is the power-calibration stage. On older writers the power determined at this stage would be used for the whole disc.

Most modern writers will also monitor the quality of the recording as it occurs, and adjust the laser power during burning to help compensate for changes in laser temperature and any dirt on the surface of the disc.

 

[randypj]

Wowsers.....thanks.
--Randy