Thomastik Infeld strings ?

[TH]

... they were an online purchase I didn't bother.

Can you tell us who you bought these from and how they responded to this problem you've shared with us? It's all very interesting to talk about it with us but alleviating this problem would be helpful. And I'd like to avoid this seller if I'm going to run into a similar problem.
Thanks
David

[rodolfoguitarra]

I´m having the same problem! The E and B plain strings oxidated very fast (5 days)! I discovered that they offer a string set with the tin coated plain strings. My strings are the Thomastick JS113...the next time I have to ask for the JS113T (this T means tin coated)

[Para]

I use TI Jazz Swing flats 13-53s I've never had any problems with them balance or oxidisation wise.

[lapideusvir]

I use TI BeBop Strings (11). They are great imo (soundwise and durability). I can recommend the PowerBrights also.