Below is a coin in my collection - there appears to be some yellow residue present which is more evident on the reverse. Does anyone have any thoughts on what the cause of it may be?
Does look kind of like pvc or something like it. Too bad it wasn’t soaked in acetone before it was graded
PVC is usually going to be more greenish, especially that much of it. It could be yellow, sometimes. Tape residue is usually going to be thicker, and sticky. I've never seen a top TPG put a coin with tape residue in a holder (especially not that much!) Usually, when I see that yellowish color, I associate it with tobacco smoke, cigars or cigarettes. Sometimes it's so bad that you can actually smell it on the coin. Those coins spend a good long while in acetone before I reholder them.
That's entirely up to you, and your intentions for the coin. If you plan on putting it in an album or dansco or something, then I would do that. If you plan on trying to sell it sometime soon, you probably don't need to. It also depends on if you want it slabbed or not - it is a fairly inexpensive coin, so I wouldn't want to the expense to resubmit if I cracked it.
This is not something I had considered and makes intuitive sense to me given what I see. Does smoke harm the surface metal? If I leave it in the slab, will it continue to get worse? At the moment, I collect Barbers for enjoyment and don’t have any intent to resell so conservation is Priority 1. However, slabs do seem to help marketability if I ever change my mind and I wouldn’t pay to re-slab a coin like this.
