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Third Friday: Cone 6 Glazes - Firing Methods

By Marsha Neal Studio
Welcome to the Third Friday Cone 6 Commercial Glaze Test Post. This month, instead of focusing on some glaze test results, I thought it might be a good time to talk a bit about how I work around the sagging rod issue with a lot of commercially available bead trees and high temperature wire when firing to Cone 5/6.

There is a lot of information out there on the internet and in previous posts here on the BOC Blog, including one on High Temperature Wire last week, and the BOC Yahoo group, so I'm not going to take the time to reinvent the wheel and research all the various links and details. Just the basics and some general photos on how I suspend my pieces on hooks and rods in order to get an entirely glazed piece and avoid sagging points and overall have a successful glaze firing all the way up to cone 6.
Decal, Cone 2 firing, but still loaded as if firing to Cone 6.
One thing that I learned - the hard way - with bent rods, fused pieces, glaze drips puddled and fusing bead trees to shelves - is that every kiln firing is different.
Pendants that wanted to kiss permanently… awww (not!)


Get to know the "weight" of your pieces and place them as evenly as possible along the rod on the bead tree. If you have a weightier piece, place that closer to one of the actual bead tree supports, not at the end or the middle of the rod, because the weight will cause the rod to sag when it heats up. It is better to be overly cautious then to be fast and not pay attention to details. You've put a lot of work into your piece to this point, don't let it slide now (literally)!

Here is a bunch of pics of my small test kiln. Knowing the inside dimensions of your kiln & max firing temperature are two important things before you purchase your kiln. Nothing like spending money on something that won't work easily for you…
Notice the nice patina on the bead trees from years and years of firing? Also, the kiln shelf does in fact have kiln wash on it. You can see the white when I removed the furniture. I don't bother to re-coat this one shelf. Also, notice that the last picture has two different bead trees in it? The kiln won't shut with the taller one, so that one does not get used as much.
Here is the small kiln after a glaze firing. See how keeping similar weighted beads evenly spaced (and hanging them from wire hooks) allows the rod to sag minimally? A quick note too - I've altered these bead trees to fit an additional row up top by adding up-side-down U-shaped wire stoppers to keep the rod from rolling off the top of the tree. I have contacted the mfgr of the bead trees to see if they would make me some with different "holes" but they will only make them with a certain number minimum order. If you might be interested in any, let me know by email and I will contact them with the design if we have enough interest.

You can also fit more in if you plan how you are going to load the kiln:
The above picture shows you how I sort my pieces out to shape and size before going into the kiln room to load them. This allows me to easily pick out the correct size wire hook (by gauge wire and length of hook) for the piece.
Now by wire hook, I mean a hook that I make with the Kemper High Temperature Wire (Nichrome). I also have some different versions of Kanthal wire to test out (bottom center picture) but that will be another post. I pre-make and then pre-fire these wire hooks using old jewelry making pliers that I don't intend to re-use for actual jewelry making. This allows me to be as rough as I want, whenever I need, without having to dig into jewelry making supplies. I keep the wire hooks in smaller containers separated by gauge. My tiny pendants get the small gauge wire, the larger ones get the larger gauge wire. Pretty simple right? Experiment and see what works for you.

Remember, the wire (hooks) won't last forever when you fire it over and over again. Eventually it will become brittle and break. The rods, well, they just get a nasty green coating from the oxidation of the metal. You could wipe it off, but it will just keep coming back. I read something more about that process somewhere recently and will have to look into it again.

Here is a loading technique that I think a lot of people use. Kiln post furniture with wire supports. Usually topped with another kiln post to keep the wire from sagging or moving.
This kind of firing works well too - but for my obsessive self - it drives me nuts to load a kiln that looks like this:

Here, I've got to end with this one to please my eyes:
…Even better upon opening :) But I never seem to remember my camera at that point because I am too excited to get it all out.

Comment away - questions, concerns, etc. I'll try to get back to you as fast as I can.


E

14 comments:

  1. Marsha, what a wonderful informative post. And thank you for continuing the talk about high temp wire and loading kilns. Your loaded kiln is a work of art. I am so in awe of how you get so much work on those bead trees. I think I will try the wire hooks on the rods and see how they help out. You certainly pack a great number in and don't have casualties. Do you have any tricks for keeping the wire from getting stuck in holes from the glaze? I use the kemper glaze saw tool to ream them out before firing but it doesn't always do the trick. Again, many thanks for the great post.

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  2. Yowsa! Now That is a kiln load and then some. Thanks very much Marsha for sharing your tricks and tips on loading your pieces in the kiln efficiently. All that balancing while making sure the pieces don't collide can be a puzzle sometimes.

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  3. Ah, good point Mary - the cleaning of the holes - before they are on the hooks (must go and update the post with that point). I usually use the Kemper zig-zag tool to clean the excess glaze out of the hole, then touch it up with a teeny paint brush. It can cause dust though, so I should add tips about keeping it to a minimum…

    If the pieces do fuse to the hook (will add pictures of that too) sometimes you can get the hook out, but often it is in there too much and has to be cast aside. I use a diamond bit with a cordless dremel and a bucket of water to dip the pieces into to clean out any sharp glaze remains after the glaze firing.

    Wow - that could be it's own post…

    And Lisa - I was just thinking about how much loading kilns for firing beads is like a big dimensional puzzle, and experience and creativeness does come in handy.

    I often want to high five myself after loading a kiln like this without any pieces falling to the bottom! Shame my dopple-ganger isn't here sometimes. ;) It's not easy work for sure!

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  4. Great post Marsha! The rack looks nice all full and lined up with the pendants.

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  5. This is a FANTASTIC post!! Thank you so much for posting all of this great information.

    What kind of rods do you use? I bought a long piece of steel wire at the hardware store (that's displayed with rebar) that I planned on cutting down so that they'd fit in my kiln...hopefully that's the right kind of metal.

    Oh, and I've tried Kanthal before...it worked great for low fire clay, but at cone 6 it sagged very badly and I lost a ton of beads & pendants. I am very interested to see if you have better results.

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    1. The rods that come with these beads trees - I believe are Nichrome. They do indeed sag at cone 5/6 - so you have to figure out balancing the pieces to avoid heavy spots where sagging happens (try putting heavier pieces closer to the stilts instead of on an end or in the very middle. :)

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  6. I LOVE your work! Would you please tell me what schedule you would suggest to glaze fire with? I'm just beginning and am worried that I'm using the wrong amount of time and temp and rate of fire. Right now I am using a low fire clay and cone 06 glazes.

    I'm also going to try putting my own racks together... your set up is fantastic! Where do you buy the parts?

    Thank you for any help you can give us!

    Lisa and Kay

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    1. These are Roselli Bead Trees, complete with rods. The other make shift "bead racks" are kiln posts turned on side. Nichrome wire (Kemper 17 ga) is used. Just like with the rods, firing to higher Cone 5/6 temperatures - be careful on where you put the heavier pieces because they will sag.

      My computerized kiln fires a glaze firing in 8 hours (pieces bisque fired to Cone 04 previously), then cools for 16 (24 hours total from start to kiln opening). Cone 06 is considerably lower temperature, and should take a bit less time (maybe 6-7 hours).

      Often times kiln manufacturers and glaze manufactures have a firing schedule depending on what you are kind of work you are doing and if it has been bisqued before vs once firing.

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  7. I've been wondering how Nichrome differed from Kanthal wire. So google knows all right? The guy below thinks kanthal is longer lasting so for the rods ( not the little hooks) maybe kanthal would be better?? http://people.umass.edu/emartz/martzpots/stan-lee/slee06.htm

    anybody else have experience?

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    1. If you can find Kanthal over Nichrome - it does last longer (I believe it does not oxidize as fast). But most of these metals at Cone 5/6 will sag if they are not balanced properly. I used to have lots of sagging issues until I sat and really figured out what worked for my work, glazes and firing schedule :)

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  8. I found out more really good info. except it's about elements not bead wires.
    sorry the link is so long but you can hi light:) also talks about the danger to your elements not just your pottery when you prop the lid open too soon.
    http://books.google.com.na/books?id=sBIQ1bRVe3IC&pg=PA54&lpg=PA54&dq=difference+between+nichrome+wire+and+kanthal+wire&source=bl&ots=_fN68M2cqs&sig=HjTTn_9uWODuE8JdK8p-0V3BOFM&hl=en&sa=X&ei=LNJyUIjWK4aGhQe_l4G4Ag&ved=0CFsQ6AEwCA#v=onepage&q=difference%20between%20nichrome%20wire%20and%20kanthal%20wire&f=false

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  9. here's a place to buy a lot of different gauges

    http://kruegerpottery.com/repair-parts/kantal-wire/kanthal-a-1-wire-15-gauge.html

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  10. Thanks so much for your informative post! I have a question about the hooks you use. You say that you pre-fire the wire hooks - do you fire them at cone 5/6 in one shot or first bisque them and then fire them at cone 5/6? I am making some pendants for the first time and started to do something similar with hooks since I didn't want large holes, but a potter at our studio believes that the wires will fuse to the pieces during firing - we also fire at cone 5/6. Have you ever had this problem? Does the pre-firing of the hooks prevent this from happening?

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  11. Ourania, the only way the wire will fuse to the pendant is if your glaze runs onto it. And even if it does slightly, you can still remove it with gentle twisting. I use a Dremel tool to grind off any remaining glaze in the stringing hole. And remember that clay shrinks when it is fired, thus making the stringing hole smaller. A lot of designers use leather, thicker wire, silk, etc. Now in there designs, so you don't want the holes too small.

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