Flash Rust Syndrome

[Carolyn Shlafer]

Here's another theory.  Some of my pieces have been sitting in the lye bath for, well... a long time.
(Months, actually.  :-[)
Doesn't seem to hurt the iron, luckily.  But even if the pieces don't rust while soaking in the solution, could the iron in some cases be so porous that the pieces actually retain moisture?   That might explain why some pieces that look perfectly fine after washing and drying still develop flash rust while in the oven for the first round of seasoning...  Any thoughts?

[Jesse and Kim Dunfee]

Jim,
  Thats some very good info. And I to didn't take the water into account. Might have something there.
Well I have nothing earth shattering to report. The pictures don't really give a good look at the coloring but I will post then anyway. I did the wagners with a vinegar wash then a coating of "Crisco". I didn't have any "Pam" but used Crisco Non Stick Spray on the Griswolds. Taking into account that this is the second time I have done this in the oven inside there was some significant differances from the way they came out on the Grill like a usually do.On the grill the seasoning came out a dark brownish color most of the time. Out of the oven all the skillets came out BLACK. And IMO the vinegar ones may have been a more even and rich black were as the Crisco Spray ones were more dull. I wiped with oil for the pictures and now wish I hadn't. So thats all I have to report. I have wiped off flash rust with a vinegar soaked rag before and left the skillets sit for a few days with no return of rust. Then seasoned.


 

[Charlee]

Nice Jesse...really nice... :)

[Chris Stairs]

Jesse,

  So, the vinegar wipe did not make that much difference to the results, but you say that it does eliminate flash rust?
  

[Jesse and Kim Dunfee]

It has for me. I do my work in steps.lye bath, scrub and clean, touch up with a wire brush if needed then wash those again. Any rust that comes along wipe with vinegar. when I get enough I start the seasoning. Some times things may sit for a week. That being said you dont want to ever let your cast iron sit in a 50/50 solution for a long time. THAT WILL cause problems. Best advise I can give is listen to the guys that have been here from the start. I have screwed up more skillets by doing things MY way ;D
  Not to say we don't have some newer members who are very knowledgeable, Sam and Charlee come to mind.
   Chris, ya gotta seriously think about this membership thing. I can tell your having fun now but the DarkSide opens up a whole new world to explore. The price of admission is nothing compared to the wealth of knowledge there. :)

[Chris Stairs]

Jesse,

That is pretty much how I've been doing it too,other than I use the self cleaning oven to clean off the carbon. Also I have never waited several days to season. Always straight vinegar to wipe off the flash rust, never a mix with water. I do it all in one day. If I were processing a lot of iron I would probably do them in lye. Since I only have a few pieces to do, a few times a year, the self cleaning oven has been good to me. If I were to start collecting seriously, I'm sure that my methods would change.

 My membership is inevitable.

[Carolyn Shlafer]

The acid in vinegar is acetic acid and it is a volatile organic compound - meaning it will evaporate like water.  Its boiling point is around 244 F, so it should dry off in an oven.  Also it needs water to be active, so if that's gone, so is most of the activity.
 

So, Jim, Jesse's successful technique of wiping down with straight vinegar as he works on a piece, as the flash rust comes up, would seem to confirm the science you're talking about...?  So there would be nothing in the form of acid to dilute or wipe off the surface of the iron (say, with oil or PAM) once the vinegar has evaporated?

[Gerald Melsheimer]

Well, let me muddy up the subject some.

All of my cleaning and seasoning is done outside with lye, electro and seasoning in a cobbled-up oven (not as efficient as a regular oven, but keep me out of hot water with the better half).

After electro I use a plastic brush and Bartender's Friend, and someitmes a Brillo pad. Then rinse off with cold water and dry.  I have found that if I get a little flash rust, that it comes off when I apply the Crisco after the initial high heat.  I use Tee shirts to apply and wipe off the Crisco before heating again.   I have not seen any difference in color or seasoning, even with some flash rust

[maloney108]

could the iron in some cases be so porous that the pieces actually retain moisture?  

I think we need to talk about this whole 'porous' thing.  Cast iron is not porous like a sponge - it won't soak things up. Cast iron does have pores, but they are microscopic and tightly filled with graphite that comes from the carbon in the melt and crystallizes out of the iron as it cools.  These little bits of graphite are part of what makes cast iron what it is.  Now on the very surface, the exposed graphite particles might fall out, be scraped out or even burned out, but these holes are only a few microns (a thousandth of a millimeter) thick and can only be seen with a big microscope.  That doesn't change the fact that the surface is truly solid and does not soak up anything.

I'm not picking on you or anyone else, Carolyn, rather I want to counter this notion that seems to be commonly misunderstood and spread around (especially on the web) by any number of folks who mean well but are just repeating what somebody else said that sounds reasonable.

[Carolyn Shlafer]

Hey, Jim, no offense taken -- truly.

As a matter of fact, that's good news.  Means I don't have to feel guilty about letting my iron pieces sit in the lye for so long...  Also, it means I have no reason to worry about the idea that the flash rust is appearing "from within" the piece, as it were.  I'm confident that one or more of the techniques described on this thread will provide a fix for my original problem.

I just came up with the whole porosity idea all by myself -- just making stuff up as I go along as it were, trying to figure it all out!!!

[Jeff Friend]

Jim is correct about cast iron not being porous.  This was discussed in the technical presentation given by Prof. Frank Peters at the convention.  If you weren't at the convention, you missed a great discussion on many aspects of cast iron.

[C. B. Williams]

A good point about the water being different that Jim pointed out. There is also another variable. Your house heating and air conditioning system, de-humidifies the air, (unless you have an automatic humidifier,) so, when either is running a large percentage of the time, the air in your house is quite dry. In my area, during spring and fall, when the hvac is used very little, the air is humid.
My point is, that the air inside your house is constantly changing in water vapor content.
Humidifiers are always used in museums and other places where art or expensive antique furniture is kept, to try and keep the air more constant, and with some moisture for obvious reasons.
So, in more humid conditions, flash rust will occur quicker.

[Carolyn Shlafer]

Jim is correct about cast iron not being porous.  This was discussed in the technical presentation given by Prof. Greg Peters at the convention.  If you weren't at the convention, you missed a great discussion on many aspects of cast iron.

Maybe some day...

[Chris Stairs]

Carolyn,

  How about an update? Have you seasoned any pieces yet?

[Carolyn Shlafer]

Nope, Chris - still trying to find some time.  Probably won't be till after my "kids" (16 & 21) are back in school/college after the T'giving weekend.

I do have one question for anyone who might know:  I have a gem pan that I got off eBay and cleaned up and re-seasoned.  It turned out great, but it could use another coat or two of seasoning.  Is it OK to use the Pam method once you've started seasoning with something else?

P.S. Maybe I should have asked this question on the thread about Pam seasoning...? :-[

[Roger Barfield]

Carolyn, I can't see why it would make any difference.  You're just going to be adding seasoning on top of other seasoning.  It will probably make it even better.  

[Chris Stairs]

Carolyn, I can't see why it would make any difference.  You're just going to be adding seasoning on top of other seasoning.  It will probably make it even better.  

I agree. What harm could it do?

[Charlee]

I've done it Carolyn...and it still works just fine! :)