Persistent black residue

[Br3tt]

At first I thought it was just leftover grime because I put in lye solution for 3 days, I scrubbed it down until the surface was kinda grey but no matter how many times I rinsed, scrubbed, and wiped it dry, a paper towel still picks up black residue every single time. I’ve tried repeated wash cycles and thorough scrubbing too, but it keeps showing up.
Is this normal carbon residue that needs another treatment step or what have I not done ?

 

[Bumpy.Lemon99]

After a full lye soak, it’s normal for carbon to keep shedding as a fine black film, since lye breaks down grease but doesn’t always remove baked on carbon fully. Many people follow with an oven self clean cycle or an electrolysis bath to strip the last layer before reseasoning. Did you stop after the lye bath or have you tried a high heat burn off step yet?

 

[Elder_Maison]

If it’s not sticky or flaky, don’t sweat it. Wiping black off a stripped pan just means you’re down to bare iron. A lot of folks keep scrubbing and end up pitting the surface. Just oil it, bake it, and the residue will lock in once you build the seasoning layers.

 

[Paul9ray]

@Br3tt I bet that the scrubber you're using isn't aggressive enough! If you're using a sponge or even a nylon scrubber, that stubborn carbon isn't coming off.
Grab a piece of stainless steel scouring pad (like a Chore Boy) or, even better, a wire brush (brass or stainless steel) that fits into an electric drill. You need aggressive, physical abrasion to finish what the lye started

 

[BigBob75]

I use a "Scotch Brite" type of circular pad in a cordless drill, Harbor Freight I think. It cleans but doesn't remove metal. After that, wash it with Comet or Ajax, then soapy water, dry it well and then just season it as ELDER_MAISON suggested. I use a very light coat of Crisco, season to 500F three times with the windows open and food doesn't stick and it tastes great. Get that old Cast Iron back in use! I fry bacon at least once or twice a week and it just helps to give more seasoning to the Cast Iron.

 

[BubblyCat]

I usually clean the loose bits with a stiff brush and a paste of salt and oil, then scrub with coarse salt or a scrubber. I sometimes use baking soda for heavy buildup.