I won a cheap T205 which had long ago been pasted into a scrapbook and wanted to see if I could soak off the paste and preserve the back. I failed to do so. Here’s a photographic essay of my efforts.
Before:
The back looked clean, so hopefully the paste would peel away leaving an intact back.
The bath:
I held it down until it stopped floating. I then let it set for two hours.
The peel:
I could read the back, but it was on the debris part. The back had stuck to the paper. I then wrapped it in a paper towel. First for an hour, then I changed the dressing and dried it for 24 hours. I did that twice. Here's the finished product.
The reveal:
It was an interesting try, but I don't think I did a very good job. I'd never have the patience to do another attempt, and I would likely be petrified at the prospect of trying it with a really valuable card.