The myth is that stumbling upon this kind of material would result in you getting charged with a crime. This whole article focuses on ONE out of DOZENS of criminal charges. So DOZENS more are valid charges not based solely on browser cache. Only persons who have vast amounts of child exploitation images on their devices ever get charged with any crime. It's simply not worth investigators, prosecutors and the courts time to charge any crime of child exploitation that is only based on a few images in browser cache.

Pledge is what our computer forensics lab uses on damaged disks they want to read. Either way I would try non abrasive tips before abrasive ones (i.e. Toothpast)