Lose finish in bathtub from cleaning/sanitizing?

All,

I don't have a huge sink to clean/sanitize my brewing/fermenting equipment, so I use one of my rarely used bathtubs...clean with 1Step/Oxiclean and sanitize with StarSan.

I usually use my fermenting buckets as the containers for the cleansing/sanitizing solution within the tub, and I follow the 'normal' concentrations: 1TBS 1Step/Oxiclean per 5 gal warm/hot water, and 1oz StarSan per 5 gal warm/hot water.

It seems that these solutions might be removing the finish from my tub. There is a layer of 'finish' almost like dried paint peeling off my tub from the drain back. There is a layer underneath this peeled off layer that doesn't seem to be damaged, so we're not at the point of bare metal.

This tub is metal and has what I believe is a normal/usual finish, similar to tubs I have had in abodes around the world. Had no loss of 'finish' until I started using/dumping the 1Step/StarSan solutions. Had used OxiClean to clean the tub before with no ill effects.

Searched here for similar issues, but only found things about discoloration from extra long soaks and what have you.

Wondering if anyone else has had this problem, any feedback/observations would be appreciated.

Thanks!

Spanky###

Neither StarSan nor Oxiclean should permeate those finishes to start the peeling, though if you've got peeling already started they can probably speed it along. Once they start, though, water gets trapped underneath and it's just a matter of time before the whole coating comes off.