burn on inside of stainless steel brewing kettle

[Photomask]

Photo #5 Scotch S/S Scrubbie
Photo #6 A S/S Toothbrush
Photo #7 Polished on a bench buffer.

Surface analysis showed:
The untreated surface of the keg interior was 24ra
The 40gt Flapwheel was 80-115 ra (depending on the location of the test)
The 100gt sandpaper was 16ra
The Green Scrubbie was 18ra
The S/S Scrubbie was 27ra
The S/S Toothbrush was 19ra
The polished area was 10ra or less.

So, just about any scrubbing short of a grinder will provide a surface near original or even better.
(Keeping in mind that this data is based on a beer keg kettle. If you have a pretty Blinkmann polished brewpot the starting surface ra is probably closer to 10ra and and scrubbing short of polishing will likely be a step down.)

Stay tuned.... The next test will be various forms of surface passivation and process specific corrosion testing on varied surface treatments. Anything particular that you guys might want to address in the next test?

 

[dmfa200]

Photomask,
You may want to start a new thread for this.
It may not get enough exposure in this thread.

 

[EarthBound]

Photomask,
You may want to start a new thread for this.
It may not get enough exposure in this thread.

I agree. For sure.

 

[Photomask]

WOW! I really thought the first post would have been a question about how the surface analysis was performed...

 

[dmfa200]

You must have a surface roughness tester at work.
What brand and model?

My prediction is, that if those were virgin abrasives there won't be much to discern other than the difference in the roughness.

Sorry, don't mean to sound like a jerk, but I've got 15 years experience working with stainless.

I've hit stainless with just about everything you can think of, short of chemicals and as long as you use uncontaminated non-ferrous tools on it, there's not gonna be any change other than the roughness you've created.

 

[Photomask]

You must have a surface roughness tester at work.
What brand and model?

My prediction is, that if those were virgin abrasives there won't be much to discern other than the difference in the roughness.

Sorry, don't mean to sound like a jerk, but I've got 15 years experience working with stainless.

I've hit stainless with just about everything you can think of, short of chemicals and as long as you use uncontaminated non-ferrous tools on it, there's not gonna be any change other than the roughness you've created.

I'm using a Federal Pocket Surf. There are better tools available for the task but for this purpose it is more than sufficient.

Virgin abrasives will leave a rougher surface until broken in. I elected to go with used as that is likely what most of such work will be done with.

Not a jerk at all. I welcome constructive input. Experience doesn't really matter. As soon as you think you know it all somebody else will show up with different experience and teach you something new. (The guy that teaches you something new could just as easily be a new kid or an old man.) I'm always up for learning something new. Just wait for the discussion on passivation and intended goals...

 

[dmfa200]

When you say used abrasives, have they been used on such things as carbon steel products? If so I can tell you what the outcome will be. "RUST!"

Surface roughness will have no bearing on corrosion. As long as the abrasive media is not contaminated with free iron.

 

[Photomask]

When you say used abrasives, have they been used on such things as carbon steel products? If so I can tell you what the outcome will be. "RUST!"

Surface roughness will have no bearing on corrosion. As long as the abrasive media is not contaminated with free iron.

These abrasives were used on stainless only.

Surface roughness does have an impact on corrosion resistance and that will be demonstrated in the next series of tests.

As for carbon or mild steel interacting if used on stainless, yes, if not passivated. That will be demonstrated in the next series of tests as well.

Corrosion will also be present in the HAZ of a stainless weldment. Also will be demonstrated in the next series of tests

I'm going to try and demonstrate the results of everything that gets argued about in regards to these areas of home brewing.

Any ideas I should include?

 

[northernlad]

I hope that wasn't directed at me.

I was simply taking suggestions for cleaning burnt stuff off the bottom of a SS kettle. After that, I decided what were valid suggestions and decided to try them out. I know I could've just used a SS scrubbie right off the bat, but I thought it would be helpful to try out some ideas. I'm usually willing to be a guinea pig, especially when it's a controversial topic.

In my case, scrubbing a little by hand would've pretty much done nothing. A SS wire brush for my angle grinder would've been required. I even bought one just in case the oven cleaner didn't work, but it did, so we're good.

Wasn't you.
I have seen a lot of reference to other's material about what will or will not happen but hadn't seen anyone who had actual with real world feedback.

 

[dmfa200]

In my experience, I have not noted any significant degree of corrosion with stainless steel in regards to surface roughness, in a neutral atmosphere, such as water or ambient air.
However, if exposed to corrosive chemicals, then yes I will agree those crevices left by abrasives can cause concentration that will lead to corrosion.

I got into a debate with one of the members on using abrasives to clean stainless steel.
The only reason I would be reluctant to do this is if I had a very expensive piece of equipment with a polished surface. Not because I would be afraid of contaminating the metal, but only because I wouldn't want to alter the polished finish.

I suggest you do a side by side comparison of stainless steel after using an iron contaminated media vs clean media.

 

[Photomask]

I suggest you do a side by side comparison of stainless steel after using an iron contaminated media vs clean media.

It was already on the list of test patches. With a carbon steel brush, a stainless steel brush that had been used on mild steel and a flap wheel that had been used on mild steel. With results to be shown unpassivated compared with three different methods of passivation. This is going to settle a lot of arguments and questions. Including a few of my own.

 

[iijakii]

Old thread - pardon the bump. It was at the top of the searches when I was checking earlier this week, figured I'd post my findings for anyone else in the same predicament.

I had some wicked scorching. There was a light brown (almost like when something starts rusting) coating across the entire bottom of my pot, and also three giant circles of a very dark / rough scorching.

• First I tried soaking in oxiclean and then scouring with a green scrubby pad for awhile. Got pretty much nothing off.
  
• Next I filled the pot with about a quarter inch of white vinegar and simmered that for awhile. 10 minutes, fifteen maybe. I could actually see the scorch coming off during the boil. Then I scrubbed it and it was much weaker/easier and I'd say about 80% of it came off.
  
• I finished with making a Bar Keepers Friend paste, applying it and letting it perform magic and science for maybe 5 minutes. Scrubbed the rest off with ease, and voila - beautiful pot.

Sadly I didn't take any before pictures, but here are two from afterwards. This pot has seen a good 30 direct-fire brews and a few BIAB mishaps where the bag ripped and I burnt grain. It looks perfect and I'm going to keep using it on the new electric rig I am building.


Cliffs: boiling vinegar works wonders.