I am the guy that Ken spoke to.
I ruined a batch of helles, by not properly cleaning my new stainless components.
I had done a quick cleaning...But, I definitely didn't do as good a job, as I should have.
I theorize that a coating of machining oil/grease & who knows what other heavy metals & filth was on some of my new components & that boiling coupled with the pH of the wort cleaned the components, far better than the lackadaisical cleaning I had done.
Consequently, the resulting beer turned out slightly darker in color & contained an astringent, metallic quality that was absolutely awful.
In talking to Ken, I'm fairly confident that he discovered the same type of problem that I had on that batch.
I don't know for 100% certain, but it seems to be a safe bet.
I traced my problem to the new stainless components, by a process of elimination.
Sodium Metabisulfite was not used in my ruined batch, so I know that was not a contributing factor.
My water filtration system was used prior & following...Also showing no contribution.
I used hops from the same 1 lb bag, on previous & subsequent batches, so I know they were not my cause.
I used grain from the same bags prior & following...Not a factor.
In truth, I later brewed the exact same recipe & found nothing like the ruined batch.
The same kettles, chiller, pump, fittings, heating element, controller, spoon, mash paddle, mash tun, etc. were all used on subsequent batches, with no ill results.
If you look into some of the processes that are used in the manufacturing of stainless components, you'll see a LOT of things used that you don't want in your beer. Greases that contain heavy metals & toxins are fairly common. Cutting oils are used, frequently.
It's not unrealistic to think that a dunk in an Oxyclean or PBW solution might not do the job.
If you can think of a better explanation, you're welcome to continue trying.
But, I believe I found the culprit in my system & have since decided to do a deep cleaning on all new parts.