Darkened inside bottom or some kind of residue on brand new stainless brew kettle?

[thehopbandit]

Hi,

I recently acquired two new stainless brew kettles. I believe they are 304 stainless. However, one of them has a much darker bottom than the other. I have posted comparison pics for reference.

As you can see from the picture, the inside bottom of the kettle appears to have a brushed finish and one of the kettles is much darker than the other. Given that it appears in a swirling pattern, I'm inclined to think it is something from the manufacturing or brushing process. The outside bottom of the kettle has the same issue, comparatively.

Using a paper towel leaves some black residue initially, but it doesn't seem to wipe away completely from the metal. These pictures are both after trying to clean with some PBW for awhile. It didn't really do much.

I was hoping someone who knows about metallurgy or stainless manufacturing could help me out. What is causing this? Any idea on how to get rid of it? Any concerns?

 

[iijakii]

I'd get some Barkeepers Friend and try to buff it out.

 

[seven9st_surfer]

I had the same thing with my Bayou 44-qt. after a batch or 2. I ended up soaking overnight in PBW and using steel wool to lightly remove all of it. No issues since.

 

[kombat]

I'd get some Barkeepers Friend and try to buff it out.

That's what I was going to suggest, too. That stuff works magic.

 

[flars]

I'd get some Barkeepers Friend and try to buff it out.

Barkeepers Friend and nothing more coarse than a wet paper towel as a buffing pad to keep from scratching the SS..

 

[feinbera]

BKF FTW!

I can't seem to finish a brew day without a ton of beer stone and colored oxidization on my stainless kettle, but a couple squirts of Barkeeper's Friend and a good scrub with one of those soft scrubbie pads sets things right every time.

But, yeah, stay away from the steel wool, definitely overkill.

 

[thehopbandit]

Well, based on all of your replies, it sounds like I'll give Bar Keepers Friend a go!

Any idea what is actually causing this residue/darkness? Is it machine oil? Something from the manufacturing process, I assume?

I had the same thing with my Bayou 44-qt. after a batch or 2. I ended up soaking overnight in PBW and using steel wool to lightly remove all of it. No issues since.

Yeah, these pots are Bayou, so that is encouraging to hear!

 

[unionrdr]

I clean my SS kettle with a Dobie brand scrubber & PBW. It leaves it shiny as new, but that's just removing extract residue. I never get that black tinge inside it? Could be the quality of the stainless, & how evenly dispersed the carbon particles are in the steel? Look on youtube for the guy that reproduces the Ulfberht swords. They go into detail about dispersion of carbon in the steel affecting it's quality/performance.

 

[day_trippr]

[...]Any idea what is actually causing this residue/darkness? Is it machine oil? Something from the manufacturing process, I assume?[...]

If these are brand new, never been used kettles, most likely you're seeing very fine metal particles and lubricant, both from the machining process. Especially if a cloth comes up blackened when wiping it down.

BKF with a stiff sponge or rag is the thing to use.
No need for an SS-safe scrubby in this case - you're not trying to cut through beer stone...

Cheers!

 

[thehopbandit]

Thanks for the help, guys. I tried some Bar Keeper's Friend today and it seems to be working....albeit slowly. I scrubbed pretty vigorously with a scour pad for a couple minutes and rinsed. Repeated this a couple times and I noticed it getting a little better each time, but still not completely gone. I'll probably have to repeat the cycle a few more times for it to be completely gone.

It definitely appears to be something from the machining process since it appears in a swirl pattern and appears in rings. I'm assuming that's how they did the "brushed" finish on the bottom. As long as it goes away, I'll be happy!

 

[heckels]

Honestly, if it were me and I'd given it a few good cleanings with BKF I would live with it. After a few brews the kettle will not be nice and shiny anymore anyway unless you're super picky about he finish and scrub after every brew or two.

I typically just use a cloth and soap at the end of my mash cycle and boil.

 

[Rcbandl]

I had the same thing with my Bayou 44-qt. after a batch or 2. I ended up soaking overnight in PBW and using steel wool to lightly remove all of it. No issues since.

NEVER EVER use steel wool on stainless. NEVER. This is not opinion, it is fact. Steel wool will leave iron deposits in the stainless and will cause it to rust. Please dont ever advocate using any kind of steel scrubber on stainless. It is very bad advice.

Once again this is not opinion it is proven, scientific fact.

 

[thehopbandit]

Honestly, if it were me and I'd given it a few good cleanings with BKF I would live with it. After a few brews the kettle will not be nice and shiny anymore anyway unless you're super picky about he finish and scrub after every brew or two.

I typically just use a cloth and soap at the end of my mash cycle and boil.

Definitely true. I'll just give it a final go and call it good. I just wanted to get of it as much off as possible since it does leave a small residue on wiping with a paper towel. I'd rather that stuff not get in my beer! Almost there! :rockin:

NEVER EVER use steel wool on stainless. NEVER. This is not opinion, it is fact. Steel wool will leave iron deposits in the stainless and will cause it to rust. Please dont ever advocate using any kind of steel scrubber on stainless. It is very bad advice.

Once again this is not opinion it is proven, scientific fact.

A good point for sure! I've just been using a hard plastic scour pad.

 

[kombat]

I use sponges with a stiffer, more abrasive finish on one side, they work great without leaving scratches

 

[TallDan]

Definitely true. I'll just give it a final go and call it good. I just wanted to get of it as much off as possible since it does leave a small residue on wiping with a paper towel. I'd rather that stuff not get in my beer! Almost there! :rockin:

If you're using the dry BKF, get the pot wet and sprinkle it around, then scrub for a minute or so to get a nice coating of thin paste everywhere on the pot. I've not used the liquid versions, but i'm guessing they can just be wiped on a dry surface. Leave it like that for a few minutes. The active ingredient here is an acid, not an abrasive, so giving it time is just as effective as hard scrubbing (unless you're using an abrasive pad to scrub with).

BKF continually amazes me with what it does on stainless steel and glass surfaces. I use it to clean the stainless steel kitchen sink and goes from dirty and dull to clean and sparkling with very little effort.

 

[thehopbandit]

Happy to report that after a couple cleanings with Bar Keeper's Friend the residue/darkness is all gone!

 

[Kornssj]

Happy to report that after a couple cleanings with Bar Keeper's Friend the residue/darkness is all gone!

Got the same thing happening in my brew kettle I just bought. Glad i checked this post!! Years later lol still going strong.