[quote="rein-o"
While these are informative for collectors this is not the case on LDs.
You might be able to see rot under some type of magnifying scope at around 100X or something but I don't have that type of gear
and am only guessing that you might be able to see it.
In my 25+ years of collecting LDs I've never physically seen rot on the surface of a disc.
Nobody knows until they play it if there are issues and not all bad issues are rot.[/quote]
The laser-rot/disc-rot thing really can cause a bit of confusion & the sometimes rot babble really does not help.
As an example only the 1995 Japanese release of THX 1138 is reported here as "Rot status - Low probability" but I am rather sceptical on that. There are coloured dots that are clearly visible at the start (during the first few minutes only) but they are on the source material used - the black sections above & below the features image are clear of any coloured dots, not a single speck on them & they are part of the mastered image so it as clearly not any form of so called "rot".
I have a few PDO pressed LDs (PAL & NTSC) that have gone grey in colour with very dark grey (almost black) spots & blotches covering the disc below the plastic but they still play well - others that look fine though are pretty badly affected by the dreaded rot.
When PIONEER took over & refitted the US Carson LD pressing plant they referred to what many people may have caller laser-rot as the "color flash issue" which was apparently a bit of a problem but they fairly quickly sorted the so called problem out (others here may be able to elaborate on that) but still had issues that did crop up over the formats lifespan that were addressed but they never called any issues "rot".
Worth checking any so called rotters in other players if possible as I have had discs that play well but can be problematic on some players & that is usually an issue with the LD player or connections. Bought a collection about 12 years ago because the owner was sure his collection was, as he put it, "all starting to rot" & even though I offered to check them he had "had enough" so I bagged the discs (around 300 LDs) & the player for what was a bit of a bargain price. The player was a Denon LA-2300 which was a clone of the PIONEER CLD-D515 that the owner had serviced by cleaning the inside of the unit which included cleaning the laser lens with isopropyl alcohol. I am not saying that he created the issue with his
service but every disc was checked (on a CLD-D515 that I used to check LDs bought in collections back then) & all but one played perfectly & it was not due to any form of rot but due to it being cracked.
Still got some of them & all still perform as they should.
There are quite a few threads on the rot thing here & some are very informative.
As above it is not a thing that manifests itself until you pop the LD into a reliable player, marks below the disc surface that play well are not rotters in my opinion & also as mentioned not all playback issues are the dreaded rot.
Enjoy the big (rot free) discs
.
Cheers