Nov 27, 2012 at 5:25 pm #1296527
@nihilist_voyagerLocale: Down the Rabbit Hole!
Sooo i kinda did a dumb- well, I had a "learning experience" the other day. I set my Ti pot on to boil and when I check it about five minutes later, I realize i stupidly forgot to put water in the pot!! Rookie mistake. Well ok, I'm a rookie.
Anyway, the outside is torched, though I'm not one for looks. What worries me is the inside being similarly messed up, and what appears to be rust or something at the bottom on one edge that I can't scrub away.
What to do? Keep or trash? Also is it safe to steel wool the rusty part away?Nov 28, 2012 at 9:49 am #1931729
@cvcassLocale: State of Jefferson
You said it was a Ti pot right, it is oxidation similar to rust but totally inert. Unless it is flaky I would leave it, it adds character.Nov 28, 2012 at 11:57 am #1931757
@bzhayesLocale: So. California
Darn I thought this would be a thread on cooking pot roast in your snow peak. I guess that explains why this thread isn't in the food section.
Anyway, I agree with above, it is oxidation which would be called rust if it were iron. If it hasn't compromised the integrity of the pot, then you don't really have anything to worry about. You should be able to clean it off with steel wool. Ignore that advice if the inside of the pot has a non-stick coating. In that case you have compromised the coating and will be eating and burning flakes of it. Teflon is not good for and I wouldn't use it anymore.Nov 28, 2012 at 12:32 pm #1931761
Yep, the boys are correct. What you have is a layer of titanium dioxide, inside and out. When titanium is heated above 1620* F, its crystalline structure converts from the alpha to the beta phase. This means nothing to you, of course. Then, when the metal cools back down past 1620* F, it reverts back to the alpha phase. This is when oxygen will be incorporated into the surface of the metal, forming a tenacious layer of titanium dioxide, measuring just a few angstroms thick. This layer refracts light differently, with the color of the patina dictated by the thickness of the titanium dioxide layer. Feel free to scour the pot with an S.O.S. pad–it won't hurt the titanium, and it might possibly shave off a bit of the oxide coating. The layer adheres to the main titanium metal quite well though. But even if some were to chip off, it won't hurt to swallow it–it has FDA approval for use as a food additive. The white letters on an M & M are actually a titanium dioxide paint.
Now, if the pot does have a non-stick surface, toss it. As was mentioned, your mama don't want her baby eating Teflon.Dec 1, 2012 at 5:48 pm #1932461
@qiwizLocale: UL gear @ QiWiz.net
I see the process Gary describes every time I make a trowel and my own FireFly stove is now a deep bluish purple color after many burns. I think it's beautiful and I would not want to scrape it off. No harm to leave it be and just enjoy the rainbow patina.Dec 2, 2012 at 11:02 am #1932584
Teflon is actually pretty safe to eat; the same properties that make it non-stick also make it almost entirely biologically inert. While I'm not saying it would be a good idea to eat large amounts of Teflon, it wouldn't do you much hard.
However, it does decompose under high heat into some less pleasant compounds, although those tend to evaporate away into the air.
If the pan was non-stick, you have ruined the non-stick-ness of the pan, but it's still safe to use, if you feel so inclined.May 13, 2016 at 2:32 pm #3402299
I know this thread is going on 4 years, but I was searching to see if it’s acceptable to use an SOS pad on my evernew. And man, am I glad I stumbled upon this thread. Gary’s post is one of the most informative posts that I’ve read in a while. If you ever read this, thanks Gary.May 13, 2016 at 4:45 pm #3402329
“However, it does decompose under high heat into some less pleasant compounds, although those tend to evaporate away into the air.”
I can vouch for the above, and also say it’s perhaps a bit understated as far as “less pleasant compounds” part. I worked at a plastics factory once. One time some teflon plastic was coming down to go through the oven to bake, and it got stuck in the oven.
I felt like i was having an asthma attack (which my brother had fairly severely growing up), had a hard time breathing, and then later i experienced some flu like symptoms.May 13, 2016 at 4:52 pm #3402331
Hi Paul. I’m glad that my description of the titanium dioxide formation was helpful to you. However, there is much, much more to the effects of heat on titanium. The grills that I make and sell are CP-2 titanium (commercially pure), and this essentially unalloyed metal pretty much acts like I described. Most of our ti pots are made from an alloy of aluminum and vanadium (type 5, or 6Al-4V). Most all of Rob Kelly’s QiWiz.net titanium products are made from 6Al-4V alloy. His wind screens are CP-2 however, because they need to be rolled up and not crack or break.
In a recent thread here, several guys much more knowledgeable than me about titanium metalurgy had described intricate details of the effect of intense heat on various alloys of titanium. Some ti alloys don’t revert back to the alpha crystalline phase when the metal cools back down past the beta transit temperature. Some will become brittle, others won’t. It’s all rather complicated, but the science is quite interesting (at least to me).
For the purposes of our discussion here, I don’t think there’s much to worry about when the metal takes on the patina from heating the pot without water in it. And I doubt that the physical properties of the 6Al-4V metal will be significantly altered, given what we use the pots for. Now, if we were to design a frame for a stealth bomber or a space shuttle or an unmanned space probe or a high performance mountain bike, we would need to use a very precise alloy of titanium.
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