One of the other sites (WW) have been having an ongoing discussion on this issue and it sounds like StazOn "may" be the the first line of defense.

After doing a little hunting I managed to find some StazOn refill ink (31 Jet Black). Primarily I use a Colop self-inking stamp so I found an old dried out inking pad and gave it a try on various surfaces including plastic and glass and the results are encouraging. StazOn (solvent based ink) actually gave me a solid black coverage on a freezer bag, the regular (water based ink) turned a very light gray roughly 10% compared to the StazOn. The rub test (after a 5 min wait) completely removed the water based ink and I had to rub a number of times to remove the StazOn. On hard plastic surface the water base failed again and the StazOn took a bit of work to remove it. Of course I did not have a new 5 to test it on and not sure what the results would be over time.

For those that are interested in trying this product check with your local scrap booking suppliers, office supplies, craft stores, and stamp suppliers.

I sourced my ink from Just Scrap It The Scrapbook Shop - 108 103rd ST E - 955-4850 - Saskatoon . They carry the ink pads and refills. Call ahead to ensure they are in stock.

Not sure this will work but it's worth a try.