Full Shelves or Half Shelves in Electric Kilns

[Mark C.]

Morgan

Post placement still needs to be about the same. Its not about warping but the thermo load.When loading the bottom the stilts need to be lined up as the thermo load is great with all that weight at bottom, as you get to the top of the kiln it is not  as critical. Its always best to line them up when you can. Even advancers cannot take huge offsets due to weight at high temps. They can break from that stress of uneven thermo loading.You have been lucky so far would be my guess.I have had corners crack odd from uneven sharp posts even thougfh they are lined up underneath. Of course my cone 11 load is often 5+ feet tall so the weight is great .

In terms of more wares from this shelves you now know they pay for themselves pretty fast with extra space. And your back is better from less weight loading. Its amazing really as they are all upside other than the cost which is recouped the more you fire.

Edited May 13 by Mark C.

[HenryBurlingame]

Does anyone here use porcelain with the advancers? The website says you need to use kiln wash if you do, but they look like a pain to kiln wash since they are so smooth and non-absorbent. Wonder how big of an issue this is in practice… 

[Bill Kielb]

5 hours ago, HenryBurlingame said:

Does anyone here use porcelain with the advancers?

Yep, our porcelain plucks. But kiln wash is super easy, super smooth or a little alumina works just fine for us.  Cone 10 furniture plucks as well but dipping the ends of furniture in kiln wash is super effective and lasts many, many firings. The weight of each load is 30-60 % lighter than ordinary shelves so to us they are worth it in reduced energy alone.

Edited May 13 by Bill Kielb

[HenryBurlingame]

Great to hear! Now if they were only ever in stock anywhere lol…

I’m currently fitting out an entire studio and never have had as much of a problem with so many things being out of stock/backordered for months as I am having with ceramics stuff right now.

[Mark C.]

 I am a all porcelain  shopcone 10 firing gas.

I would make my own wash and remove with a wet sponge  before firing any commercial wash as it usually poor quality.

Speaking of quailty wash I noticed on the Advander shelves (kiln shelve.com ) site they use the same formula as I posted years ago

1/2 alumina hydrate

1/4 epk

1/4 calcined EPK or (glowmax)

I apply a VERY  thin coat with a paint roller after shelves get warm in sun and when dry scrap the edges of wash

Edited May 13 by Mark C.

[neilestrick]

I've done the math on the cost of Thermal-Lite and CoreLite shelves for my 28" wide kiln, and it will take almost 875 firings before I break even with the more expensive shelves, and that's with buying two sets of the CoreLite because they won't last as long. Because I would only save 1 7/8" of height per firing in a glaze firing with the thinner shelves, and half that in a bisque, it's like getting a free firing every 19 loads. That averages out to $1.11 savings per load, which isn't much.

This is also assuming I never accidentally break any of the Thermal-Lite shelves, and that I actually fire the kiln 876 times over the life of the shelves. For me that's not a problem, but for the average hobbyist who does 2 firings a month, that means it'll take 36 years for the more expensive shelves to pay off. However, for a production potter the extra 2 inches of space means 5% fewer kiln loads, which can really add up if you're firing a lot. And if you have a larger kiln than a typical 27" tall electric kiln, like a large gas kiln, then the payoff will come much faster.

As for the weight of the more expensive shelves being so much better, they're really not. The 26" half round Thermal-Lite and CoreLite I used in my calculations have a weight difference of only 1 pound, so it's really not enough to make a significant difference in wear and tear on your body or the cost of firing.

[fergusonjeff]

There might be a little more to the calculation than you accounted for in just the economics.  I have a mix of both corelite and advancers for both my large electric and my gas kilns.  I had lots of issues with warped shelves and the corelite were much better.  I was still getting a lot of warping in my slab plates with the core-lite shelves.  The advancers completely fixed the warping.  I don;t think it is only because they are very flat.  I think they heat the ware a little more and allow slab plates to settle perfectly flat on the perfectly flat shelves.  I use the advancers for slab plates and the core-lites for bowls and mugs.  I recommend a mix of advancers and core-lites for a compromise in firing properties and economics.

[neilestrick]

37 minutes ago, fergusonjeff said:

There might be a little more to the calculation than you accounted for in just the economics.  I have a mix of both corelite and advancers for both my large electric and my gas kilns.  I had lots of issues with warped shelves and the corelite were much better.  I was still getting a lot of warping in my slab plates with the core-lite shelves.  The advancers completely fixed the warping.  I don;t think it is only because they are very flat.  I think they heat the ware a little more and allow slab plates to settle perfectly flat on the perfectly flat shelves.  I use the advancers for slab plates and the core-lites for bowls and mugs.  I recommend a mix of advancers and core-lites for a compromise in firing properties and economics.

I've never had that problem, even with the really thick CoreLites, but I can totally see how it may be an issue.

[Dick White]

We have been using Advancers in the glaze kilns at the college for over 10 years. Costs were not an issue as we got grants. The main reason we liked them so much is they are nearly indestructible (if you treat them properly). With student glazing errors, drips pop off with a stiff putty knife and a few swipes with an old green grinding wheel held sideways cleaned up the rest. No more chiseling and grinding divots into the corderite shelves, no more kiln wash. When we bought new kilns at the community studio, I just told them to buy Advancers for the glaze kilns. Same problem with everybody trying to do the Amaco drippy layered look and causing puddles of glaze on the shelves. Maybe in your own private studio, you have better control over your glazing, and when you make a mistake, you learn from it (which the students and community users don't pay the price for their errors). In my personal studio, I do some crystalline glazes which, by definition, are runny. Sometimes the catcher pot breaks from the stress. Advancers to the rescue.

[Mark C.]

I cannot speak about the hobbist world as it not my area of experince. But in the cone 10-11 world of firing like gas kilns they pay off quickly . My car kiln holds average  of 33 shelves per fire (12x24)the Geil is now averaging about 19 shelves per fire (14x28)

I have been thru silicone carbide in the 70s 3/4 shelve was the norm-I have a huge pile of warped ones (anyone want them?) then switched to some 1 inch mullites all warped fast then went whole hog into 50  one inch dry pressed english high alumina. They held up really well ,but weigh 33# a pice and and loading was a bear at 35 car kiln loads a year,I bought a set of 40 -5/8th mullites shelves for bisque loads to save spave and my back.

The thing that is not in this equation and as a potter for over 50 years is your body-hands and back .especially the money side (ecomonomics pale in this equation).I switched  out to all advancers and thermolites and never looked back -yes I did gain almost 2 feet in each load but my back-my god my back really deserved it. So in my view as a potter at 70 its a lesson for you younger ones -take care of your feet (good shoes) your back (lighter stuff) your hands/wrists.

Now I do use those high alumina in my salt kiln as they are the best I have seen in that environment by far. CoreLites in my view are honey combed mullits shelves and yes they work well at lower temps but they are heavier than advancers /theromlites

My school of hard knocks lessons are work smarter when you are younger as it pays off body wise in your later life. Lighter shelves if you can swing them are worth it. A few firings a year -not worth it.I bought mine in the 90s and wish I had done it sooner. I did just buy 7k worth of the thermolites for my new to me Geil (the shelves cost more than the kiln.).

In a world like Dick is in its makes the most sense . If you break one (no big deal) I  have broken many in my 30 years with them and always fine a use for the pieces-they make wonderfill thin nerd to add to post to gain just a bit (wash all sides)

No one who I know has bought them and wished anything other than my god why did I not do this sooner -but that in the professional world  not Hobbist.

I have bought many of them lightly used and that price is always higher than any other type of shelve as they never wear out or warp

If and when I sell mine  in my future I know they will have great value as they in a class by themselves.

Pottery is hard on the body and lighter shelves pay off in spades in my view.  I like Fred Flinstone just as much as anyone else but really in cermaics I'm more of a Jetson guy

 

 

Edited May 15 by Mark C.

[oldlady]

tomorrow is the day i will be talking to bailey about buying thermal lite shelves.  at 83, i am now really unable to reach the shelf i use as a bottom.  i think it is 1 1/2 or 2 inches above the floor.   my neighbor works with glass and i asked her to take out the last firing since i really could not lift the 9 whole solid shelves out.

 it is unfortunate that i never knew about kiln wash on my posts.  not using it has made my shelf bottoms have holes and my wonderful triangle posts have bumps in the same shape as the holes.  i run the posts over a belt sander now and hope they get level enough to match each other.   

so i think i will be very happy not to have to lift those shelves any more.   only 4 or so are not bowed in the center.   what is your advice about stacking since the lightweight ones are what i need for the bottom area.  will the heavier ones work on top of them without causing breakage? evening the bumps on the posts will prevent one tiny spot from causing trouble.   and, i will mix up some more of Mark's kiln wash.  i applied it years ago to the old shelves and have never needed to scrape it off.

those of you who have used the light shelves have valuable experience, will you please share any advice to make this easier for me?

 

[oldlady]

well, i thought i could get several 21 inch whole thermal lite shelves but at $337 each, my last sale would only buy 3 of them.  a full kilnload runs about 8-9 shelves, the very heavy solid  shelves i have had for 30 years or so.  you can understand my dilemma.

so we discussed cordelite ones.  they weigh only 14 pounds for a 21 inch whole shelf and cost $83 each.  i have no experience with them.   do they warp? 

any opinions?  my age and the prices of the work i make would make a bookeeper laugh at the question.  i only care about the weight and being able to continue to work. 

[Mark C.]

Yes you can use heavier ones on top of the light one . Buy the three now and more later. Many folks add more over time.

[neilestrick]

5 hours ago, oldlady said:

well, i thought i could get several 21 inch whole thermal lite shelves but at $337 each, my last sale would only buy 3 of them.  a full kilnload runs about 8-9 shelves, the very heavy solid  shelves i have had for 30 years or so.  you can understand my dilemma.

so we discussed cordelite ones.  they weigh only 14 pounds for a 21 inch whole shelf and cost $83 each.  i have no experience with them.   do they warp? 

any opinions?  my age and the prices of the work i make would make a bookeeper laugh at the question.  i only care about the weight and being able to continue to work. 

I've used CoreLite shelves for years, and I really like them. They stay flat much longer than standard shelves, and are as light as Advancers/Thermal-Lites. I think half shelves will last longer than full shelves, though, so if you don't need full shelves don't get them.

[Mark C.]

I agree on the 1/2 shelves-much easier to use unless you have to have fulls for large platters