"Grease like" stains on brand new CDs?

Hello.

Thing that was bothering me for some time. It happens quite frequently that brand CD has a discoloration on the bottom side that looks like "stain" something like on the picture here: https://scontent-frx5-1.xx.fbcdn.ne...=03fd1f5b56a31f168da6715e62c8c66f&oe=59E158CC but mine are usually less visble and not so regular (rather swirls that concentric). I heard that CD polishing machines can create such visual effect, but it is not the case as it is on CDs that are taken straight from the store shelf. I never had problems with playing such disc and on some forum about DVD movies i read that it is normal and happens in production process. anyone can put some light on this?

 

The first time I remember seeing those "swirl marks" in the aluminum substrate was in 1990 when I purchased Captain Beefheart's US Reprise The Spotlight Kid/Clear Spot 2 on 1 cd. It played fine, but I returned it for a replacement and of course, the second disc had the same swirls, so I kept it.
2 years ago when I re-ripped my entire cd collection using FLAC and AccurateRip, I could not obtain a 100% AccurateRip of this disc. I tried 3 different drives with no success. But, my 1990 Reprise German issue of the same title has no swirl marks and it ripped perfectly. When I compared the DR data from the completed rips from the US Reprise to the German, they were identical so I assume both discs share the same mastering.
I know this does not answer your question of why or how these swirl marks made their way to cd's, but this is just my observation of one of my trials with it.

 

Meanwhile i got a feedback from a guy that was working at the pressing plant. Those stains are not in the aluminium itself but in the plastick that covers it. It should not have any negative impact neither on the playback on the cd durability and as he said it is quite more common esepcailly with modern pressed CDs because nobody bothers to move it our ot of sales or replacing anymore. So looks like your ripping problems may be just a coincidence.

 

I remember seeing that bad when I was buying cds. Its not like any residue on the disc but I don’t know where the odd discolouration comes from...