JD18-JH Update: Kanthal A-1 Elements

admin | Kilns | Tuesday, April 29th, 2008

With the new JD18-JH, I was supposed to get 2.2 mm Kanthal APM elements. At the point where the kiln was ready for shipment, there was a 4 week wait on the APM wire of that gauge, so I opted for the 12 gauge (≈ 2.0 mm) Kanthal A-1.
One of my plans was to compare the lifespan of APM to A-1, using digital images, ohm measurements, and kiln interface software (K.I.S.S.) to record what was happening as each set started to go.
An educated guess was that it would take longer for the APM’s to fail, so I thought that it made sense to get the A-1’s first after all.

I’ve fired several kilns in the past using both “standard” (15 gauge) and “heavy duty” (14 gauge) elements. With either, once the coils start leaning in on each other and bunching up in the corners, their performance declined quickly.
Most of those past firings were in the ^9-10 range, occasionally pushing for a “soft ^11″. After about 15-20 firings, the elements would show the leaning and bunching described above. Past that, I’d average 25-35 firings total before the rate of rise to peak was noticeably slowed, and my firings suffered.

Currently, I’ve performed almost forty ^11-12 (true 90° bend on a self-supporting cone) firings* with the JD18-JH.
When graphed, my rate of rise is still tight with the programmed set point line, and ohm readings taken after each firing remain the same… but hey, pictures are worth a thousand words:

Unfired 12 gauge Kanthal A-1 Elements:

Kanthal A-1 Elements 2.0mm New

…the same elements, after the 37th ^11-12 firing:

Kanthal A-1 12 gauge Elements, Firing 37

The elements settled nicely into the element holders after the first firing… aside from that, and the oxidation coating on the metal, the elements appear to be in perfect condition.

My Current View on Kanthal A-1 vs. APM Wire:

With A-1’s being less than half (almost 1/3) the price of APM’s, the latter would need to possess at least 3-4 times the life span of the former to qualify the difference in price. One could argue that the downtime associated with replacing the elements factors into the equation; however, if I can get 100+ firings in between element changes, I’ll really have to consider whether I want to replace them with APM’s. My reasoning here, is that accidents can happen with either… For instance, if a bit of glaze, ceramic, or even so much as a few grains of sand fall onto your APM element, I don’t imagine that it would have a better survival rate over any other wire. At that point, replacement costs can really hit home.

*Note: For the record, there are also nine ^04 bisque (I usually use my other kiln for this), and sixteen low temp luster/ glass enamel firings on this element set.

6 Comments »

  1. Hi,
    You have a great site. I am interested in your review of the Kanthal A1 elements. It is now about 10 months since you published this review and I am wondering if you views have changed. How many firings did you get before there was significant degradation in the performance?

    Thanks

    Tymen

    Hey Tymen,
    In regards to how many firings I get… Well, I haven’t found out yet :)
    At 80+ firings in the ^10-12 range, they’re still going like new!
    ~jesse.

    Comment by Tymen Brom — February 19, 2009 @ 11:51 pm

  2. L&L just made another sale when I saw this 80+ posting. Astounding results and special thanks for generating this detailed professional assessment. I applaude your diligence.

    Paul O.

    NICE -thanks much, Paul!!! Enjoy the new kiln, and let me know how things go…

    ~jesse.

    Comment by Paul Ouzts — June 21, 2009 @ 5:18 am

  3. Hello Jesse.
    I bought one of these kilns about a year ago and it is a really good kiln for growing crystals.
    I was also debating in the beginning to get APM elements but with a new kiln that came with the Kanthal elements upgrading to APM was still a additional $500 or so. I decided to use the Kanthals first and then decide wether I wanted to spend the extra money for the APM. I am now on my 135th firing,a few of those are bisque (maybe 10) but the most are ^10 firing and they are still working good. They are starting to lean into each other a little and it is taking a few more minutes to reach temperature; but I just lower the top temperature a few degrees and am still getting great results.
    So I am not sure that the APM’s are the way to go seeing the price difference.

    Ok then see you at Phil’s in october.

    LTR
    Robert.

    Hey Robert,
    135 firings -that’s great to hear!
    I’m not convinced that APM’s are really necessary in regard to a JH series kiln. My view of APM’s in general is that if a piece of glaze, clay, silica, etc lands on your elements, or if a glazed pot falls on them during a firing, that metal isn’t going to stand up to it any more than Kanthal A-1. If an accident does occur, then the APM’s are going to cost A LOT more to replace.
    With nearly 90 firings on my current set of elements in the cone 10-12 range (and all the reports I’ve gotten from others using this gauge of Kanthal), I can’t see myself ever going with APM’s.

    Looking forward to Phil’s as well!
    ~jesse.

    Comment by Robbrecht Troost — July 22, 2009 @ 3:38 pm

  4. Hello Jesse,
    Thank you for your very useful information. It’s a big help.
    I have been fireing cone ten oxidation in a gas kiln for years. I want to start fireing electric because I am moveing to a house with very good solar panels.
    I am looking a the L & L e quad and the JH series. Can you tell me which one you would recommend? Is the JH series a better choice even though it is $5,000 compared to $3,000 or the e quad?
    I drop cone ten and do not tip cone eleven. I do not fire crystals so I do not hold at cone ten.
    Thank you. David

    Hm. I guess I would suggest speaking with the folks at L&L and explain what you’re wanting the kiln to do. When I was collaborating on the design for the JH series, I was after a kiln with a longer lifespan and less maintenance where high temperatures (^10-12), even firing, and rapid cooling are necessary. Keep in mind that many components on a ^10 kiln aren’t actually rated for that temperature range. ~Jesse.

    Comment by David — September 30, 2010 @ 8:04 am

  5. hey jesse,

    do you know, is the only positive thing about the APM’s over the A-1’s their lifespan? Or can the APM’s fire faster? or to higher temps? (i know thicker kiln brick helps with higher cone fire.) i just started doing crystalline firings several months ago. i have a skutt kiln bought all standard and i would like to try some ^11 and ^12 crystalline glazes but i am pretty new to the scene and have been afraid to try anything over ^10 since thats the max for the kiln (so it says). i know upgrading the brick to 3″ helps, but i also heard APM elements helps attain higher cones and was considering getting them for this reason. is this true? i have had great crystal success since day 1 so the elements i have now are great, but i wanted to push the cone rating a bit and wasnt sure if my elements would be ok with that.

    The main concern I have with APM elements is that they are expensive and just as vulnerable to being destroyed if (for instance) a speck of glaze lands on the element when loading, or a piece falls during the firing, etc. I know folks with 140+ firings to the ^10-12 range on the thicker gauge A-1’s of the JH series kilns, so I don’t see the benefit of APM’s myself. ~Jesse.

    Comment by greg beckman — December 20, 2010 @ 6:18 pm

  6. Fechral is made of three metals – iron, chrome and aluminum. The alloy name combines first letters from it’s components names: Fe – iron, Cr- chrome, Al – aluminum. Iron is the base metal of fechral. There is 70% of iron in this alloy, apart from manganese and silicon.
    Nickel or other elements may be added to this alloy for special characteristics. Various concentrations of main components and additives determine consumer values of Fechral. Fechral is high-resistant metal, it reaches 1,2-1,3 mkOm. Fechral also has high fusion temperature 1500°C and low density – 7.2g/sm3, what makes this alloy slighter than nichrome. Comparatively cheap Aluminium, which is used in this alloy, makes production expences 6 times cheaper than nichrome. Fechral is also corrosion-resistant to oxidation, carbonaceous and sulfuric environments. Also this alloy is resistant to air, vacuum and argon environments.

    Comment by Ira Vanleeuwen — December 23, 2011 @ 5:19 am

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