When does flash rust change from being something that happens to a problem?

[Lewis Downey]

I am cleaning a Lodge Biscuit Pan. It went through the lye bath and electro no problem.  For good measure I soaked in it a citric acid bath for a while. Bottom line, when it was clean, it was *clean*.

I could not dry the nooks and crannies fast enough to prevent flash rust. Final wash was cold water. I used clean dry red shop towels (my favorite) after a quick initial dry with paper towels. I used a microfiber towel after the shop towels and poked the microfibers into the crevices using a pen.

The result is shown below. The pics have been slightly enhanced to accentuate the rust.

When does flash rust go from being something that happens and turn into a problem? And what to do to prevent it in this case.

[Lewis Downey]

A few days later I hit the pan with a nylon brush on a Dremel tool. It knocked off the bulk of the rust, and I am confident the nylon bristles do not damage the iron.

Results are shown below. The rust actually worsened while the piece sat unattended before being dusted with the Dremel Tool. There is some flash rust remaining on the cooking surface, but that is not the rust that bothers since towels will reach into those areas.

[Duke Gilleland]

Last pic looks great. Would season and bake up a pan of "Cat Head" biscuits!! Merry Christmas! [smiley=santa3.gif]

[Russell Ware]

Not being able to scrub or dry the recesses of the pan is the cause of your flash rust here. It is the nature of the beast confronted by all who restore cast iron. Find a way to eliminate it or prevent it, and you are on to something then.
Of course, the first thing I noticed about your pan was the raised dot appearing in the medallion logo on the bottom. That’s a shift mark. I would appreciate it if you would take a close up photo of it and post it under this thread:
http://www.griswoldandwagner.com/cgi-bin/yabb/YaBB.pl?num=1407724173
As for the yellow precipitate, that is more than likely ferric citrate forming as a result of the citric acid bath. Your subsequent brushing of the pan removed the precipitated iron salt, so I would expect you are clear to season it now if there is no flash rust left under where the precipitate was covering. Flash rust is not something that you can easily prevent. The amount of flash rust your piece develops is dependent on how much of the post-electrolysis reduced iron you can remove by scrubbing. That is the reason why pans like these can be so frustrating to clean. It may be expensive, but many here use Evaporust (sp?) to reduce/eliminate scrubbing. The only alternative is manual scrubbing with steel wool or small brushes.
As you can see in the photo below, part of my solution was to find an earlier version of the pan that has the cutout open frame. Once Lodge started making the closed frame version of the pan (like the one you are cleaning), the underside of this pan becomes a nightmare to restore/clean. It makes buying a new preseasoned pan look easier than cleaning a used pan.

[Scott McCarrick]

I have wondered what would be the result of taking a clean wet CI piece and dropping it in a bucket of canola oil.
The oil should push the water out and to the surface, correct?

[John Arsenault]

Scott, Oil floats on water, so I would think that the oil would trap the water in the iron. Hand dry with paper towels place in oven at 250 to drive out the water, then oil.
John A

[Cheryl Watson]

When I apply the oil, I use more than usually and brush it in well around 'flash' rust, use a little more again.....

The Flash Rust will slough off nicely..... :)

[Lewis Downey]

Of course, the first thing I noticed about your pan was the raised dot appearing in the medallion logo on the bottom. That’s a shift mark. I would appreciate it if you would take a close up photo of it and post it under this thread:
http://www.griswoldandwagner.com/cgi-bin/yabb/YaBB.pl?num=1407724173

Hi Russell,

Picture posted.

Does Evaporust eliminate scrubbing at the end? Or eliminate flash rust after scrubbing?  I used Evaporust on several pieces but always scrubbed them afterwards. I do not recall whether or not those pieces had flash rust or not.

Maybe a simple answer to the question in the title is that flash rust becomes a problem when you cannot find a satisfactory way to remove it. In this case a nylon brush on a Dremel tool took care of the bulk of the rust.

The biscuit pan seasoned well enough. The recesses on the back held onto oil just like they held onto water. As a result, the recesses are blacker than the rest of pan -- not that you'd necessarily notice when looking at the piece. Over the weekend we made tasty gruyere and chive 'popovers' that might have been called anything other than popover. They did rise above the top of the muffin pan for a bit.  I'll practice that recipe in this pan in the next day or two. A hockey puck sized  gruyere and chive 'biscuit' should compliment a number of other dishes and might look great on a plate.

[Tommy Harris]

I have been monkeying around with the flash rust as well.  Some pans are worse than others.    One thing I have found that appears to be helping a little bit, at least for me, is partially drying it quickly, hitting with a quick mist of Pam, wiping it down, throwing in the 200°oven to dry for a bit, then oiling to season or store.    So far it has helped me quite a bit.   I wouldnt say it's 100% but it is helping.   

[Cheryl Watson]

I have learned that there are TWO critical factors in reducing Flash Rust:

1.  COLD, constantly "Running Water" only, for final scrub down. (do not fill the sink with water and submerge to scrub).  Keep the flow of water constant to carry away what you are scrubbing off the surface.

2.  Dry piece thoroughly with paper towels, quickly, and then into 'preheated' 250° oven to complete the drying process.

[Valerie Johnson]

I have found that rinsing my iron in my laundry room washtub that does not have an aerator on it causes less flash rust than rinsing in my kitchen sink which does have an aerator on it.