I just went through my Red Book listed Braided Hair Large Cents (1839-1857). 33 coins -- 20 PCGS -- 13 NGC All were all purchased already slabbed 5-10 years ago. [I'm cleaning them up in readiness to image all of them.] It "appears" from this small sample that NGC slabs were made of harder plastic than PCGS slabs. I had to remove scratches from a LOT more PCGS slabs (percentage-wise) than from NGC slabs. (Or is there some other factor involved?) Just an observation.
Apparently you meant "cleaning up" the plastic slabs themselves and not the coins within them. Gave me a brief cringe, though. LOL
It might just be a coincidence (no pun intended ). I have actually noticed scratches more on NGC holders than PCGS. I think the condition of the holders depends on how many times they were sold, shipped, and touched by each owner. Edit: I also remembered that NGC at some point started offering scratch-resistant holders. However that might have been after your coins were purchased; so that might not really explain your results.
They are certainly different plastic. The NGC plastic tends to spread the light across the surfaces a little more than the PCGS. You'll notice this as glare. Most PCGS plastic is very easy to image through as the reflections from the light stay more concentrated compared to NGC. Most of this is moot however, unless you have coins that have a lot of color that you are trying to show off. Also the PCGS holders seem easier to be easier to clean up compared to the NGC.
NGC slabs have a softer plastic, though neither is really soft. The NGC ones just have the entire face at one level. As mentioned buffing PCGS slabs seems to be much easier and the newest PCGS slabs seem to be the hardest to scratch.
I don't know about you but these 2 statements seem to be in direct contradiction to each other. I say that because scratches on harder plastic would be harder to remove, not easier. Now I have no idea which one is harder, they may both be exactly the same for all I know. What I do know is this, when trying to remove or polish out scratches on a slab, it is far more likely that the one with deepest scratches is going to be the one that is hardest to polish out. Shallow scratches on a harder plastic would be easier to polish out than deep scratches on a softer plastic. And if they're both of equal hardness .............
NGC has several generations of plastic, and their newest is additionally available with a scratch-resistant (not scratch-proof) coating. In my experience, the PCGS slabs of every generation take a polish better than the NGC slabs of any generation. The newest NGC slabs hairline more, and the older ones (not the "fatty" ones) have a textured surface that is really hard to get looking good.
Softer in a relative sense, as mentioned though neither is really soft soft. Like everyone else though and the countless threads, can't for the life of me find a reasonable good way to buff NGC slabs without making a huge project out if it.
