White cloudy areas on bottom of new stainless steel skillet

Sprinkle the 'cleaned' dry pan with coarse salt - add any kind of inexpensive vinegar, just enough to wet the salt to a wet paste, scrub the pan with this paste with a paper towel for 30 seconds or so, using the salt as a mild "abrasive", while the vinegar dissolves the cloudiness. Rinse with water and dry. Voilá.

This is simpler and cheaper than using any kind of kitchen cleanser, and no toxic residue.

This guy:

Stainless scrubbing pad

Just clean stainless with stainless, you'll never look back.

If salt pastes do not work, a good option is BarKeepers Friend, the powder form is available in any hardware store for couple bucks. Its oxalic acid and work wonders for stainless steel.

It's hard for me to believe the answer is mineral deposits. After one cooking and one wash, white cloudy marks on the inside bottom of a brand new pan, and in fact on all the pans and pots I used from this new set. And yet I have another stainless steel pan that I've had for years that has never accrued this mottled, unattractive staining. I think it must be a cheap quality of stainless steel, and maybe the fact that the tri-ply also has aluminum in it.

This is kind of late but never use a stainless pad on polished stainless steal. Bon Ami will do it. You can find it nest to comet. It is non abrasive, you may also need to grab some Wenol. We used both at William Sonoma's kitchen. I've had my All Clad stainless tri ply for 22 years and they still have a mirror finish.