I just received my Novus plastic cleaner kit. Not surprisingly part of the instructions say, "Test in an inconspicuous area!" The first slab I encountered that needs "help" is an NGC and happens to contain one of my top 5 favorite coins. I'm definitely NOT testing on that slab. So I have to dig around to find a scratched NGC slab to test on. But if PCGS uses the same type of plastic that broadens my possibilities AND will also set me up for any PCGS slabs that need the treatment too. QUESTION: Can anyone tell me if both PCGS and NGC use the same type of plastic in their slabs?
I don't know, but they may provide more information on their individual sites. Now your making me want to know also. Good question!
Both probably use inert plastic, there could be differences in hardness I would guess that the softer ones would clean up easier than the harder ones, let us know how the experiment goes. I have some scuff marks on my gsas
I found an 1854 large cent in NGC AU-53 that can definitely benefit from some scratch removal on the slab. Not an expensive coin, so that will be test #1. Then I need to find a PCGS slab. I'll post results (before and after) when I get them.
in my experience using meguiar's PlastiX auto plastic polish, which works well, PCGS slabs are easy to clean up light scratches, deep ones need more work of course. NGC slabs are tougher to clean up, especially the newer ones. Not sure if it's just a harder plastic or just that the product i use doesn't match with their plastic as well??
I'm not sure what brand the one I purchased from the auto section at Walmart is but it works great on all types of plastics. I'm not a coin slab person and break out every coin I get in one. But I've used that scratch remover from Walmart on my eye glasses, miscellaneous plastic stuff around the house and mostly on those solar panel lights. Those get all messed up from the weather and this stuff cleans that all right off.
I got confused and started a new thread about my first test on polishing a slab. See "Plastic Polishing Kit - First Test Results Are In".
We need Lehigh and his materials science background on this one. I have to assume that they both use the same type of plastic. Did a Google search but struck out (except I found your posting!).
All I found was NGC indicating they are putting a protective coating on some of their new (edge view) slabs. Nothing at PCGS.
Kanga: Info about the type of plastic/polymers these TPGs use is likely proprietary to ward off counterfeiters and competitors since they have a lot invested in security/securing coins and grades. I would also float the idea that that 'protective coating' you mention on the new edge view slabs might be UV protection. A lot of delicate art on paper is presented framed behind UV Plexiglas and Lexan brand sheeting materials. It seems UV protection might be a beneficial feature on some coins and paper currency as well. I mention this UV possibility in the event that your plastics repair chems happen to have any warnings about use or non-use on plastics with/without UV properties. This and your other thread are very interesting. Hope to learn from your experiments with the slabs and repair kits. Don't forget to post pics as you progress. Thanks.
If I read the NGC statement correctly, the coating is for scratch protection. They likened it to the coating put on glasses lenses. As nearly as I can tell, no chemicals are used by these particular polishing compounds. They are strictly very fine abrasives, like jeweler's rouge.
Anyone who has cracked NGC and PCGS slabs knows there is a difference in the plastic. PCGS is much harder and more brittle; it's easier to crack out since it snaps. NGC is more pliable, and gives before it breaks. As a chemical engineer, I can talk the paint off the wall about polymer science but I don't that helps here. The bottom line is simple - find a low-end coin in a slab, try the scratch remover thing, and see.
No, PCGS' plasitc is SIGNIFICANTLY harder than NGC's when it comes to polishing. Said another way, you're going to have to use a lot more elbow grease to polish those PCGS slabs. Hope this helps...Mike (who has polished more than a few slabs in his day)
All I know is that NGC plastic seems easier to scuff up and when polishing it is easier to make things worse.
Novus should work on all plastics. One of my other main hobbies is plastic model cars, and many people use Novus on them. All different kinds and ages of plastic used. I don't polish mine as a personal choice, though, I tend to make it look much worse then better.
