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Thread: The case FOR dry burning

  1. #1
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    The case FOR dry burning

    Firstly, I hope this is of interest to people, otherwise I just wasted a whack of time....

    Secondly, apologies for the dreadful quality of the photomicrographs. I couldn't find my microscope camera. It's in a box around here somewhere.... I had to use a 10x zoom camera held up to the eyepiece.

    After my efforts with the Kanthal dual coil on the Kanger mini subtank I decided to have a closer look at the Kanthal coils to see what is going on when the build is used for a week, and what affect my normal cleaning method (scrub with an electric toothbrush) has on it. I've been starting to avoid dry burning on the advice we seem to be getting from the experts but to be honest physical cleaning just doesn't seem to have the same effect as a dry burn. Hopefully this will show you why that is.




    First, a couple of shots of the used coil with the wick still in place. I've squeezed the wicks between a tissue to remove excess liquid and may have moved the wick in the coil very slightly.




    As you can see the the deposit is friable. While some of it has adhered to the coil a lot of it has broken off and is on the cotton. It might be the action of vapourisation that contributes to this as liquid in the deposit is turned to vapour. Some of it was probably spread around when I soaked up the excess liquid too.
    ---------------------------------
    Next, I washed and cleaned the coil. I've found an electric toothbrush does as good a job at physically cleaning the coil as anything. The bristles are soft enough to not damage the build, but the action is vigorous enough to remove anything on the coil that can be removed. By eye the coil looks very clean but not exactly "shiny and new"



    Up close you can see that while there are bare spots on the wire, there's also a lot of deposit still adhering to the coil. My eyes not being what they used to be, the coil looked clean if a bit dull. The photomicrograph seems to show the real story however.
    ---------------------------------
    Given the result of the physical clean I decided to do a dry burn and have a look as well. I ramped the power up (from 7 watts) in stages to burn the coil, and gave it a final dry burn at 14 watts for 10 seconds. Since it's a dual coil it should have been about 7 watts per coil. Both coils were glowing equally.
    I then washed the coil again and repeated the brushing treatment as for the physical clean.



    As you can see, this is a completely different story. All of the deposited material has been removed and the coil looks shiny throughout. You can even see the forming marks on the wire which would have been there from manufacture. The colour of the wire is very similar to what we'd expect from unused wire and there are no signs at this magnification of any physical damage to the coil from the dry firing.

    Given that I haven't had a great experience with only physically cleaning the coils in the past, and looking at this visual record, I think I'll be dry firing from now on to freshen a coil. I think I can recommend a physical clean after dry firing to remove any particles, contaminants, and loose metal oxide that may potentially find it's way into the vape.

    If you personally have decided not to dry fire kanthal coils even given this visual evidence, I recommend that you re make the atomiser coil completely once it reaches the end of it's useful life.

    My other observation is that the friable nature of the deposit does not look healthy to be breathing on. Things always look more scary in close-up and it may be harmless (I'm not a doctor or a scientist) but I think I'll be taking old coils out of service much sooner than I have been in the past.

    Please note that this is Kanthal wire. I'm not making any statements about the relative merits of doing any of this with Ni200, Ti1, SS316, or any other type of wire.

    I'm also not making any statements about the safety of dry burning any metal wire including Kanthal. In alloyed wire such as this the different elements can migrate and you can get different alloys (percentages) forming at the surface of the wire, although given the stability of Kanthal and it's intended purpose I would expect this to be much less than what happens in stainless steel wire for example. You can also get oxide layers with different phases and physical properties forming very quickly. We're still waiting on research that can tell us what is really going on with these metals, so as with anything to do with vaping use at your own risk.
    Last edited by fabricator4; 18-03-16 at 02:45 PM.
    gtadmin, Fatman, btobw and 12 others like this.
    Chris: Tobacco free since 17:00 15th March 2013.

  2. #2
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    Excellent info thanks mate

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    Quote Originally Posted by act180 View Post
    Excellent info thanks mate
    Glad you found it useful!
    Chris: Tobacco free since 17:00 15th March 2013.

  4. #4
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    Excellent write up mate
    Ignore the Super-moderator tag in my profile, I have resigned from that position but admin have not updated my profile as yet

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    Quote Originally Posted by gtadmin View Post
    Excellent write up mate
    Thanks GT!
    Chris: Tobacco free since 17:00 15th March 2013.

  6. #6
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    By the way, when I said there is "no signs at this magnification of any physical damage to the coil" I meant the surface structure of the wire. You can actually see that the coil must have been under some tension before it was fired, because the high heat has relaxed it and the shape of the coil has changed slightly. The coil would of course need to be neatened up before re-wicking it again.
    Last edited by fabricator4; 18-03-16 at 04:01 PM.
    Chris: Tobacco free since 17:00 15th March 2013.

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    Great write up, thankyou.

  8. #8
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    Interesting stuff
    Cheers bud


    Big shout out to AVF and Everyone that helped me on my Journey to quit the the Death Sticks

  9. #9
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    Thanks guys!
    Chris: Tobacco free since 17:00 15th March 2013.

  10. #10
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    Thank you for taking the time to put this together.
    Really enjoyed reading it.

 

 
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