iridescence after seasoning

[Lewis Downey]

Is this a problem?

[Mark Zizzi]

Is this the same skillet/griddle as the one in your "discoloration" thread? I don't really see any iridescence...but if you do, that would not be normal.  :-?

[Russell Ware]

You may have seasoned over flash rust. So yes, it could create a problem with the seasoning lasting, and it could hide more rust that is forming.

[Lewis Downey]

Mark,

Yes, this is the same skillet from the discoloration thread. The pinkish area close to the handle is where the iridescence is visible in the photo.

Russell,

I will run it through the lye bath and electro again. It also soaked in a mild acetic acid bath for a while. A Lodge 10SK shows some of the same thing. They were seasoned at the same time.

There is not much time between coming out the the electro and going into the oven. What should I do if flash rust occurs? 

Earlier today I thought about scaring up an Xcelerator hand dryer to blow water off of these pieces at a rapid rate -- and to dry my hands  in the darkroom.

[Cheryl Watson]

Lewis, as I stated on the other thread,

I recommended more Electro.

It did not appear that all the imbedded rust had been effectively removed,,,, yet.

I always assume that dark spots are still harboring 'bad' rust that still needs treatment.

You may actually find pitting underneath those dark spots, but at least you will know you've gotten it all.

Best thing to help avoid flash rusting is to do final wash downs with COLD water.  Thoroughly dry the piece with paper towels, until they come away clean,,,, then into oven for drying at 225°. (if using a gas oven, always vent the moisture from the oven by cracking the door open for a minute or two, before placing iron inside). 

[Mark Zizzi]

Ok...i saw that pink but it was so faint I wasn't sure. The only thing I can think of that would be of concern is if at some point some sort of petroleum product came in contact with it. Probably unlikely for a shallow griddle like that but who knows. I would give it another round of electro, like Cheryl said. If you still see it, wipe it good, season it and then look. Normally you won't still see it and you're good to go.  Plus the electro should help that discoloration, and the seasoning will help cover the discoloration too. Flash rust is something we all have to deal with...wipe it off as good as you can and get in the oven..it's usually superficial.  ;)

[Lewis Downey]

Ok thanks! Just to make sure I understand, enough time in the electro and the dark spots from yesterday's post will go away. Once they are gone the griddle will possibly/probably show pitting. If present the pitting will be ordinary iron color - not dark.

As a side effect, the iridescence from today's post will also disappear since lighter surface rust and/or petroleum film will have gone away too.

[Trevor Lawrence]

After the electro, Rust/Pitting is almost always darker and very hard to blend with the rest of the iron. Always scrub the dark spots first... then blend the rest of the iron with the color of the dark spot.

In my experience, i have seen that "iridescence" when a piece has been polished (wire wheel, scrubbed hard with scrubby) and heated with high heat. I call it a rainbow effect.

Not all pieces that have been polished do it... i can't really explain why? Its just like the 100's of other mystery's that happen during cleaning/seasoning. Each piece has lived a different life. Best thing i have found for the iridescence, if i see its been somewhat polished.... i season at a lower temp first, then use high heat. The coat of oil seems to protect the iron from the high heat causing the iridescence. Thats just my .02

[Lewis Downey]

Thanks Trevor

... then blend the rest of the iron with the color of the dark spot.

What does it mean to blend the rest of the iron with the color of the black spot? What technique is involved?

In my experience, i have seen that "iridescence" when a piece has been polished (wire wheel, scrubbed hard with scrubby) and heated with high heat. I call it a rainbow effect.

That could be it. I scrubbed the piece hard with a deteriorating scrubby several times. It was seasoned with the oven set at 500°F. With our oven that could mean a temp that is higher than advertised. I've determined that the oven heats above the stated temp then slowly drops temp, then reheats. When I season with 500°F I have come to expect a gray result, not even close to black.  If I season between 425 and 500 I get a darker result. I am working to gain understanding of what temp turns the seasoning gray with each oil with our oven. Pam, Crisco, and Avocado oil are the ones I am working with. The avocado oil turned black above 500°F on one skillet and but went gray on another. I heat to 550° with that oil since its smoke point is something like 520°F.  I cannot tell at this point if the difference in color is primarily caused by inconsistencies in my technique or if it is primarily due to the specific iron. Knock wood, it is my technique.

If the temp is lower, like 400 to 425, I tend to get a seasoning that is more brown than black, especially with Crisco.

How do you know when a SS scrubbie is shot and should be replaced?

[James Wilson]

Thanks Trevor
How do you know when a SS scrubbie is shot and should be replaced?

When the effort to result ratio alters. I use the green synthetic 3M pads

[Cheryl Watson]

Lewis, what brand of SS scrubby are you using.

I use the 3M, and have noticed in the past 2 years, that they don't last as long.... sigh.... quality on many products has really tanked in the past 24-36 months on an escalating scale.

When they start shedding small pieces of SS strand, I replace them.
<don't want shredded bits of SS clogging up my plumbing.. :)>


I NEVER use 3M green scrub pads on my Cast Iron. Very abrasive.

[Lewis Downey]

I have occasionally wondered if green Scotchbrite scouring pads would cause any damage in the cleaning phase.

[Lewis Downey]

Cheryl,

The pads you have pictured are the exact ones I use. They are definitely starting to shred
and leave bits of SS in unwanted places.  I have one more left in the package and will pitch the others.

Too bad about the green Scotchbrite pads. I really like them.

[Russell Ware]

Lewis, the green Scotchbrite pads have aluminum oxide in them. They are like sand paper. You want something that will clean a surface without changing the surface.
Oh, and I can vouch for small pieces of ss scrubbies clogging drains. Just keep a drain screen in your sink.

[Cheryl Watson]

Another thing I discovered is that I bought some of the 3M Scrubbies at Sam's Club... Industrial size pack.

http://www.samsclub.com/sams/scotch-brite-ss-scrubber-16-ct/prod13240120.ip?navAction=

And they are coarser, and don't clean quite as well<seem less density>.... but I do use them on larger pieces. :)

Oh, and I can vouch for small pieces of ss scrubbies clogging drains. Just keep a drain screen in your sink.

Yep, I keep a sink strainer in, BUT I was seeing small pieces migrating thru the holes...
Now 4 years ago, they lasted twice as long.... :(

[Russell Ware]

Cheryl, I think over the years we also get better at scrubbing. I tested the ss scrubbies I use. They are mildy magnetic (some stainless is not). Maybe putting one of those magnets used for cows in the P-trap of the sink would help. Do they still make 'em? All the FFA kids used to bring them to school to show the city kids.

[Cheryl Watson]

Well I'll be danged!

Just went and grabbed a magnet... <never had occasion think of that before>, and yes, they are magnetic,mildly.

HMMMM....

Now I have no idea what a cow magnet is... :-?

[Russell Ware]

They give a pretty good description here:

http://www.amazon.com/Dowling-Green-Cow-Magnet-Alnico/dp/B001F0F5L8/ref=sr_1_2?ie=UTF8&qid=1424568222&sr=8-2&keywords=cow+magnet

[James Wilson]

  I NEVER use 3M green scrub pads on my Cast Iron. Very abrasive. 

Cheryl, I don't find them to be overly abrasive at all.
Perhaps the 3M product is different down this way??
I use them after electrolysis to remove the black oxide, so not much effort is required or used.
The cast iron we are rejuvenating has likely had a history of metal implements being used on them , maybe scoured with abrasives also. A little application of a 3M pad has negligible effect in my experience, well none that I have observed.
Here is a 12" Romany pan after electro, 3M and soapy water, dilute phosphoric acid wash then rinse and towel dry.
The marks on the base were red oxide burns, now clean.
3M didn't mark it, in fact they break down far too quickly :(

[Mark Zizzi]

I use one too, James. I start with a SS scrubbie and lots of hot water and soap. When the suds seem to stay white you think you're done. Then go over it with a scotchbrite pad and the suds are dirty again. I have never noticed any scratches or other damage on black iron, but I should add I use a worn one I had, not a new one. But they hold soap really well, and something about the texture of them gets the iron cleaner than a SS scrubbie alone, imo.