Most coins are perfectly slabbable after NCS treatment unless there is unseen damage to the surface of the coin under the contamination. PVC residue like that will start to etch the surface of a coin given enough time but if caught early, the surfaces will be fine. That is the whole point of NCS conservation- to return a coin to market acceptability. You do not need to pay for a service to clean a coin in a damaging manner, anyone can do that themselves
