Stainless Steel mesh, Oxide discussion.

[Pete54]

I wonder what kind of torch that would be? Below is what I come up with from a quick search.

The maximum adiabatic flame temperature a propane torch can achieve with air is 2268 kelvins (3623 °F / 1995 °C). The maximum adiabatic flame temperature a butane torch can achieve with air is 2243 kelvin (3578 °F / 1970 °C).

There is more to it than simply the temperature of the flame. The object being heated dissipates heat which lowers its temperature. In real terms, the torch is just capable of melting brazing rod (above 800 °F / 427 °C) and may melt copper (1984.32 °F / 1084.62 °C).

This can be improved if the gas is burned with oxygen. Some propane torches are also used with a tank of pure oxygen to achieve a flame temperature nearing 3095 kelvins (5110 °F / 2820 °C).

 

[Kurt]

It was a butane creme broulee torch, with a tight blue roaring cone.

 

[zoiDman]

Someone just informed me that their torch that they use for oxidation goes up to 2500 C. That is very hot. Not saying, given we don't have Boden's results yet, that it is too hot, but it is far hotter than the study cited.

I think maybe they have their F and C mixed up.

2,500 C = 4,532 F

And 4,532 F is Hot Hot Hot. Melt just about any Metal (except Tungsten) Hot.

 

[Kurt]

Thanks, Zoidman, I did mean 2500 F, not 2500 C. It would be about 1370 C.

 

[zoiDman]

Thanks, Zoidman, I did mean 2500 F, not 2500 C. It would be about 1370 C.

No Problem Kurt.

2500 F / 1370 C sounds very doable for the type of Torch you said they had.

 

[DrMA]

Certain types of SS, particularly those with low (or zero) Al and Mo content and lower Ni content (such as 309), exhibit volatilization of the Cr(III) oxide layer and subsequent oxidation of the vapor phase to Cr(VI) at temperatures above 950°C
Elevated Temperature Oxidation Resistance - TP309S 1.4833 Stainless Steel

Fortunately, fine wire mesh for filtration tends to be type 316, with higher Ni content, 2-3% Mo, and traces of Al and Si. This makes it more resistant to corrosion and oxidation due to the formation of mixed metal oxides (spinel). There is no mention of Cr(VI) in the oxidation profile of 316 SS either in air or water vapor.
Oxidation Resistance of 316L 1.4401 1.4404 Stainless Steel and Improving

 

[Kurt]

Certain types of SS, particularly those with low (or zero) Al and Mo content and lower Ni content (such as 309), exhibit volatilization of the Cr(III) oxide layer and subsequent oxidation of the vapor phase to Cr(VI) at temperatures above 950°C
Elevated Temperature Oxidation Resistance - TP309S 1.4833 Stainless Steel

Fortunately, fine wire mesh for filtration tends to be type 316, with higher Ni content, 2-3% Mo, and traces of Al and Si. This makes it more resistant to corrosion and oxidation due to the formation of mixed metal oxides (spinel). There is no mention of Cr(VI) in the oxidation profile of 316 SS either in air or eater vapor.
Oxidation Resistance of 316L 1.4401 1.4404 Stainless Steel and Improving

But it looks like those studies were just up to 900C. You may well be correct, but these temps are potentially higher than that. I think the test results Boden is getting will say much, and may well remove much of the uncertainty, positively or negatively.

 

[junkman]

But it looks like those studies were just up to 900C. You may well be correct, but these temps are potentially higher than that. I think the test results Boden is getting will say much, and may well remove much of the uncertainty, positively or negatively.

900C is 1650 F. I doubt I ever got any mesh that hot.

 

[DrMA]

But it looks like those studies were just up to 900C. You may well be correct, but these temps are potentially higher than that. I think the test results Boden is getting will say much, and may well remove much of the uncertainty, positively or negatively.

I'm not sure what tests Boden is conducting, but those studies seem to indicate the conversion to Cr(VI) oxide happens in the gas phase, which means no residue would show up on the SS itself. In addition, CrO3 has a high vapor pressure (b.p. 251°C) and is very soluble in water, so quenching the red-hot wick in water would pretty much wash out any and all of the Cr(VI) that was not previously vaporized.

 

[Boden]

But you must admit that there is a lot of evidence for Cr(III) and none so far for Cr(VI).

???????? You might want to read post 367 http://www.e-cigarette-forum.com/fo...eel-mesh-oxide-discussion-19.html#post8719082

I'd say the weight of evidence tends to support the use of SS wicks as safe.

That is a Fallacy of insufficiency.

 

[DrMA]

???????? You might want to read post 367 http://www.e-cigarette-forum.com/fo...eel-mesh-oxide-discussion-19.html#post8719082

The mention of Cr(VI) in Table 3 of that publication is wholly unsubstantiated by any of the data they present. It could very well be a typo.

That is a Fallacy of insufficiency.

I'm not sure I agree with that. Multiple people are scouring the net for evidence of Cr(VI) resulting from the oxidation of SS and little or none seems to be around. The absence of evidence in a thorough and systematic search actually has information content, and thus carries weight in and of itself. The Fallacy of insufficiency applies when no thorough research has been carried out.

For example, you can search for a bag of cash in your attic and find none. That is not an absence of evidence, it is an absence of a bag of cash.

An example of the fallacy is what the King County board of health did: there's no evidence that ecigs are safe, so they should be banned.

 

[zoiDman]

The mention of Cr(VI) in Table 3 of that publication is wholly unsubstantiated by any of the data they present. It could very well be a typo.

...

A Typo?

I thought this was a Peer Reviewed Document?

If this document contains Typos, then the document is not very valid. Or do we just take whatever we don’t like, or don’t understand and Brand it a Typo?

 

[urahara]

The mention of Cr(VI) in Table 3 of that publication is wholly unsubstantiated by any of the data they present. It Multiple people are scouring the net for evidence of Cr(VI) resulting from the oxidation of SS and little or none seems to be around. The absence of evidence in a thorough and systematic search actually has information content, and thus carries weight in and of itself. The Fallacy of insufficiency applies when no thorough research has been carried out.

this makes sense ...
but I would rather trust the results of a test than a good argument.

 

[Boden]

I'm not sure what tests Boden is conducting, but those studies seem to indicate the conversion to Cr(VI) oxide happens in the gas phase, which means no residue would show up on the SS itself. In addition, CrO3 has a high vapor pressure (b.p. 251°C) and is very soluble in water, so quenching the red-hot wick in water would pretty much wash out any and all of the Cr(VI) that was not previously vaporized.

It is true that conversion of Cr(VI) does happen in the gas phase but that does not exclude it occurring in the solid phase.

Source: http://www.boydmetals.com/Cr-Ni-Mo Alloyed Stainless Grades.pdf

"Chromium as Cr(VI) compound can be found in fumes and
dust formed by grinding, polishing, abrasive blasting, hot rolling,
hot forging, thermal cutting or welding of stainless steel."

"Dust and fumes which may be produced as a byproduct during grinding, polishing, abrasive blasting, hot rolling,
hot forging, welding, brazing, thermal cutting, pickling and postfabrication cleaning..."

Hot forging, and brazing of SS occur at temperatures similar to the orange glow temps used when oxidizing a wick.

I agree that washing the SS after oxidizing would dissolve some of the Cr(VI) (if it exists) into the water. I guess people could buy some reductant for disposal.

 

[Boden]

The lab I sent samples to are using these tests redundantly.

http://www.epa.gov/osw/hazard/testmethods/sw846/pdfs/7199.pdf
http://www.epa.gov/osw/hazard/testmethods/sw846/pdfs/7196a.pdf

 

[junkman]

I really appreciate the comments of both Boden and DrMA, and I hope they keep digging on this. I don't want to give up my SS wicks, but I also don't want to ignore health issues.

 

[DrMA]

I'm not taking this lightly. I've switched to using unoxidized SS wicks covered in cotton until we can get a definitive answer on the Cr(VI) issue.

 

[Chris474]

Wow...I had just got two more AGA-Ts in the mail and started reading this thread while vaping away on my charred SS wick with 32 g nichrome coils....that's all gone now. I have subscribed and will be back...I've switched over to 28g kanthal that I hadn't been using with the Peter K method. It took about 9 coils to get to 1.5o. I'm using non-oxidized SS wick without any cotton....here's how. Drip on the coils with no wick and run them dry 1 or 2 times. Keep the wick really loose in the coils. Here's what they look like.

They both worked fine on the first shot...no shorts, no hot spots...having done this twice in less than 45 mins, I am now wondering what took me so long to do like this...

Thank you sincerely for all of the great info here in this thread. Its certainly the most important information I've read on the ECF to date and I will surely be back often.

EDIT: worked well enough last night, but now this morning there's not enough juice vaping...it was a shot, but it looks like I'm cotton bound... Searching for that silver lining, at least it should be easy to ring the wick and swap out cotton when needed...grrrr....the slight flavor change with the cotton, the added cottony-whatever flavor is really not very disappointing but its also not the crisp SS wick flavor. I'm a bit saddened.

Perhaps its time one of our most AWESOME vendors pick up a load of 3mm OD, 2mm ID fused quartz tubing and cut it to neat little 1/2 lengths and sell them for $1/piece. I've been wanting to try that anyway and now I'll have to spend $20 to get a 4' piece.

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[chet]

I've never used SS wicks before, currently using cotton wicks. What was the purpose of oxidizing the SS wick?

 

[Chris474]

You put a coat, a layer, of oxidation & carbon on the wick to insulate it, electrically, from the coils.

Moreover, you need contact between the coils and the wick to effectively vape your juice.

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