Black residue?

[Paula Maidl]

I am new to cast iron, and have cleaned and re-seasoned 3 skillets so far using Cheryl's wonderful instructions (thank you Cheryl!).  All the skillets look good, but one is still giving off a black residue on paper towels after being heated and oiled.  The surface of the skillet doesn't appear any different than the other two in looks and texture, but the others do not give off the black residue.  Any ideas what this might be?  Is this a normal thing or not?  Should I start over with the cleaning/seasoning again and see if that resolves the issue?  Thanks for any thoughts/advice you can share.
Paula

[Cheryl Watson]

Paula, every once in a while I come across a skillet that just likes to keep shedding carbon...  (is it by any chance a Wagner? )  :)

It's hard to say if it was a slight difference in the balance of ingredients in the molten iron, that causes higher graphite content, or some sort of acidic exposure over the life of the skillet.....   

I would just try a few additional coats of seasoning, and then start using it.

 :)

What oil are you using to season with?

[Duke Gilleland]

I have more trouble with BS & R doing this when it happens :-/

[Russell Ware]

Paula, to get a better idea of what the ‘black’ material is, wash the oil from the skillet. Wipe it dry with a paper towel. Let your paper towel sit out on the counter for a while (15-30min). If it stays black, it is possible that it is some type of carbon residue. If it turns brown/orange after that time, it is iron.
I’m not sure what cleaning method you are using. If you are using lye and then 50/50 vinegar, trying letting it soak a while longer in the vinegar bath. Scrub it down in a very sudsy and soapy water bath. If the particles are still there, you can always season the pan, and then repeat the cleaning method. When the oil polymerizes from heating, it should help to bind and ultimately remove these particles.
Every piece of cast iron has its own personality.

[Paula Maidl]

Thank you all very much for the replies and suggestions!  The skillet in question is a Griswold #10.  I originally used Lye-based oven cleaner, and 50/50 vinegar and water solution to clean and de-rust, then used Pam to season in 500 degree oven (twice, per Cheryl's instructions posted to this forum).  However, I did not leave the skillet in the vinegar water solution very long, as it did not really have any rust.  I probably only left it in for about 30 minutes.

Russell, I did wash off the oil from the skillet, paper-towel dried it and left it out, and it stayed black.  So it sounds like I can either go ahead and use it, and let it build up some additional seasoning to hopefully reduce the shedding, or I could re-clean and leave it in the 50/50 solution a little longer this time and see if that helps? 

I am relieved to hear that you all think the likely culprit is carbon residue, which I'm assuming is not too bad of a thing to consume.   :)

Thanks again!
Paula