If you could do it all over again – kiln shelves recommendations for a beginner? (yes, this is another post on shelves)

[moonari]

Hello, fellow potters~!

With the pandemic pausing our local community center pottery classes and the departure of my favorite teacher, I  purchased a wheel a year ago – and after a few trips into dropping off / pickup for firings (bisqueware to glaze) at a pottery store 25 mins away, I've made the plunge–as so many on this forum have, to finally get a kiln~! Skutt 822-3 has been ordered and I'm excited!

When I purchased the kiln, I decided not purchase the furniture kit at the same time because I'd come across a random video on youtube that talked about issues with your typical Cordierite kiln shelves (warping, glaze runs, kiln wash flakes, etc.) that made me want to research more options. Thus, it's lead me to this site where I've been reading through several posts and seeing various recommendations surface. It seems like the Advancer shelves or nitride bonded silicon carbide are a much appreciated option over the standard Cordierite kiln shelves—albeit with a significant upfront cost. I've also seen recommendations for the Thermal-lite and CoreLite shelves, but apparently, they do not appear to come in the size that I need. It looks like Advancer shelves do come in the size I need. What I'm less certain of are:

• Now or later Is now the right time to make an upfront investment? Or, as a newbie, would you rather have started with a standard Cordierite shelves and 'graduate' up later?  If you had to do it all over again, what would you recommend for yourselves? 
• Shelf qty Is the way I'm calculating shelves and stilt quantities correct? It seems like the bottom-most shelf should be on a 1/2-1" stilt to improve circulation (at least from what I've seen on, youtube). Since the 822 is 22" deep, and given that bottom requirement, I've calculated that I could essentially have: 
  - bisque firing 3 shelves to stack ware, with posts / stilts at 6"
  - glaze firing at max, 5-6 shelves, using either 4" or 3" posts / stilts, respectively 
  - I juuuust may be able to have the budget to cover purchasing 3 full shelves, and 6 half shelves to achieve this— is the number of shelves unrealistic, given the space? 

To help answer the questions, maybe it might help to know more info? 

• What kind of clay body do I use? I usually throw B-mix that fires to cone 10; I also throw cone 10 Porcelain (which I heard has flux and will need either a kiln wash on the shelf or application of a mix of alumina hydarte with wax resist to the foot of the piece)
• What kinds of objects do I throw? I mainly focus on low profile bowls (2-5" tall), plates, but am starting to throw small vases and hope to also do teapots and larger bowls at some point
• How frequently do you I plan to fire? While I wish I could do more, realistically, I am only able to throw on weekends and on some evenings once in a while, unfortunately – so the firings will be based on my schedule and how much I can throw! 

Appreciate you reading this far — and please, if there is a post that already covers this that I did not find, please feel free to link it in the response for me to follow up.

Looking forward to hearing from the community! 

moonari

p.s. I'm so glad this site is here!

 

[neilestrick]

39 minutes ago, moonari said:

I've also seen recommendations for the Thermal-lite and CoreLite shelves, but apparently, they do not appear to come in the size that I need. It looks like Advancer shelves do come in the size I need.

A 15" Corelite shelf will fit just fine.  Corelite shelves are the best compromise between price and durability.

You'll need a shelf at the bottom, so don't forget to count that. I would not invest in more than 1 or 2 half shelves for a kiln that size. They're not a good use of space in a kiln that small. I rarely use a half shelf in my 18" kiln, and it's almost always just one at the top when I have a couple of tall pieces that I can fit a half shelf next to. Put your money into full shelves, and get as many as you can afford, at least 5. Get a full kit of posts, lots of sizes.

[Min]

Couple thoughts, first off no way would I routinely fire to cone 10 in an electric kiln. Element life goes down logarithmically as temperature rises. You would likely get roughly about 40 firings to cone 10 before your elements needed replacing compared to at least double that for cone 6, (plus bisque loads) There are some really nice cone 6 porcelains available. I find cone 5 B-Mix doesn't throw as nicely as the cone 10 though.

Second thought is regular cordierite shelves are not rated to cone 10, you will land up with taco shelves as they warp. Even at cone 6 they can warp quite easily. If you don't want to loose a tiny bit of kiln stacking height room with Corelites and Advancers are too steep I'ld get high alumina shelves. I think what it comes down to is budget plus how strong your back is but at just 15" the weight shouldn't be too much. You could always use the heavier high alumina shelf on the bottom of the kiln as you won't need to remove it then use Corelite for the other(s).

Welcome to the forum.

 

[shawnhar]

10 hours ago, Min said:

Even at cone 6 they can warp quite easily.

This makes me very sad... Iv'e had my eye on some 26" for my big kiln because of the price, but why would anyone ever buy these if they warp at cone 6? That is the most common glaze firing.

[Min]

3 hours ago, shawnhar said:

This makes me very sad... Iv'e had my eye on some 26" for my big kiln because of the price, but why would anyone ever buy these if they warp at cone 6? That is the most common glaze firing.

I’ve had a couple 20” square ones, and 20” round ones, can’t remember the thickness, both warped fairly quickly. Fired to a hot cone 6 with heavy use. Size and thickness of the shelves will be factors.  Perhaps there is a quality difference between manufacturers or they are better suited for lowfire, at least the ones I had which were from Seattle Pottery Supply.

edit: good article by Bill Schran comparing the pros and cons of different types of kiln shelves. https://vincepitelka.com/wp-content/uploads/2019/04/Kiln-Shelf-Options-by-Schran.pdf

Edited June 29, 2022 by Min

[moonari]

13 hours ago, Min said:

Couple thoughts, first off no way would I routinely fire to cone 10 in an electric kiln. Element life goes down logarithmically as temperature rises. You would likely get roughly about 40 firings to cone 10 before your elements needed replacing compared to at least double that for cone 6, (plus bisque loads) There are some really nice cone 6 porcelains available. I find cone 5 B-Mix doesn't throw as nicely as the cone 10 though.

Second thought is regular cordierite shelves are not rated to cone 10, you will land up with taco shelves as they warp. Even at cone 6 they can warp quite easily. If you don't want to loose a tiny bit of kiln stacking height room with Corelites and Advancers are too steep I'ld get high alumina shelves. I think what it comes down to is budget plus how strong your back is but at just 15" the weight shouldn't be too much. You could always use the heavier high alumina shelf on the bottom of the kiln as you won't need to remove it then use Corelite for the other(s).

Welcome to the forum.

 

Thanks for the tips thus far – and for the tip to try clay at cone 6. I had primarily only done cone 10 because that was what the studio had required and so that's what I have on hand.  In speaking with a Skutt technician before placing the order, they had mentioned that firing at cone 10 might go a little longer just because it was a smaller kiln and I ordered it with the 3" brick insulation. But the technician also recommended trying it before making the splurge for APM. That said, it makes sense that for an electric kiln at home is different than the large one at the studio and to try other options. I have never tried using clay at cone 6 but I'm assuming it is comparable. I'm almost out of my cone 10s and so I think I'll try throwing at cone 6 next. It'll open a world of glazes as well!

I saw a note on one of the suppliers site that Corelites won't actually hold up for long with repeated firing at cone 10 and to consistently rotate shelves so all signs are pointing to trying to adjust clay choice to cone 6. 

Since there wasn't a comment on the number of shelves, it sounds like what I have in mind isn't crazy talk?  

[neilestrick]

54 minutes ago, moonari said:

That said, it makes sense that for an electric kiln at home is different than the large one at the studio and to try other options.

If they're firing to cone 10 in a gas kiln, then they're probably firing in a reduction atmosphere. You can't do that in the electric kiln, so the glazes won't look the same. Find a cone 6 clay body that vitrifies at cone 6, not a body listed as cone 6-10, and start testing cone 6 glazes.

[moonari]

4 hours ago, neilestrick said:

If they're firing to cone 10 in a gas kiln, then they're probably firing in a reduction atmosphere. You can't do that in the electric kiln, so the glazes won't look the same. Find a cone 6 clay body that vitrifies at cone 6, not a body listed as cone 6-10, and start testing cone 6 glazes.

This is a super helpful tip! Love this. Thank you!

[Piedmont Pottery]

If I was starting over now I'd invest in nitride-bonded silicon carbide shelves, not necessarily Advancer brand, there are lower cost options from other suppliers.  The lighter weight, durability, and ease of cleaning glaze drips are worth the investment in my opinion.  

[Mark C.]

Another option is a small gas kiln and just keep firing to cone 10 -Gas kilns tend to be a bit more of ahassel to get a permit and install but its still an optione depending on where you live

[moonari]

8 hours ago, Piedmont Pottery said:

If I was starting over now I'd invest in nitride-bonded silicon carbide shelves, not necessarily Advancer brand, there are lower cost options from other suppliers.  The lighter weight, durability, and ease of cleaning glaze drips are worth the investment in my opinion.  

That is what I've been gathering from here and there. Any sources, sites, or suppliers  you recommend checking out? 

[moonari]

8 hours ago, Mark C. said:

Another option is a small gas kiln and just keep firing to cone 10 -Gas kilns tend to be a bit more of ahassel to get a permit and install but its still an optione depending on where you live

I haven't thought of that before because I had only seen large ones and I am quite space limited but that would be a neat idea to figure out at a later time. Thank you for the suggestion --and for anyone else out there, something to consider. 

[Piedmont Pottery]

16 hours ago, moonari said:

That is what I've been gathering from here and there. Any sources, sites, or suppliers  you recommend checking out? 

I've used shelves from Bailey:  https://www.baileypottery.com/store-dept-gas-electric-kilns/store-kiln-furniture-and-accessories/store-kiln-furniture-and-accessories-kiln-shelves/nitride-bonded-silicon-carbide.html?gclid=CjwKCAjw2f-VBhAsEiwAO4lNeCDMQHtm_ooKpUqdLy1sQeTHy4OvagoRK25cnlwCob9kL9_vLHS7PBoCZFMQAvD_BwE

and Axner: https://www.axner.com/nitride-bonded-silicon-carbide-kiln-shelves.aspx

[Pres]

I purchased a new kiln last year with the furniture kit, knowing that I would want to add more shelves in the future. I have always used cordierite shelves when teaching, and in the old kiln. I have not had issues with warping at cone 6, yet I have seen problems with other teachers that did not understand how to best place stilts. I have always used 3 stilts to support  a shelf as this seems to give the most balanced support for the work and health for the shelf. I also make certain to keep fresh kiln wash on the shelves to limit the amount of pucks from glaze drips. . . best way to eliminate them is to clean bottoms well, use bevel undercuts, and catch lips on  pots that will allow glaze run. even an engraved line on a foot area is often enough to stop a glaze run.

 

best,

Pres 

[moonari]

23 hours ago, Piedmont Pottery said:

I've used shelves from Bailey:  https://www.baileypottery.com/store-dept-gas-electric-kilns/store-kiln-furniture-and-accessories/store-kiln-furniture-and-accessories-kiln-shelves/nitride-bonded-silicon-carbide.html?gclid=CjwKCAjw2f-VBhAsEiwAO4lNeCDMQHtm_ooKpUqdLy1sQeTHy4OvagoRK25cnlwCob9kL9_vLHS7PBoCZFMQAvD_BwE

and Axner: https://www.axner.com/nitride-bonded-silicon-carbide-kiln-shelves.aspx

Thanks, Piedmont. These links will be great for anybody who’s looking. It helps hearing from someone who’s actually used them.I wasn’t able to find the right size for my kiln (15” diameter) but am curious if anyone has ever cut them at home? I can’t imagine it a super great idea unless you know what you’re doing but I wonder if it’s like like cutting a corian countertop? Then that would be a way to do it, I suppose, to order the 21” and cut down manually to size, leaving 1” from kin interior edges.

[moonari]

21 hours ago, Pres said:

I purchased a new kiln last year with the furniture kit, knowing that I would want to add more shelves in the future. I have always used cordierite shelves when teaching, and in the old kiln. I have not had issues with warping at cone 6, yet I have seen problems with other teachers that did not understand how to best place stilts. I have always used 3 stilts to support  a shelf as this seems to give the most balanced support for the work and health for the shelf. I also make certain to keep fresh kiln wash on the shelves to limit the amount of pucks from glaze drips. . . best way to eliminate them is to clean bottoms well, use bevel undercuts, and catch lips on  pots that will allow glaze run. even an engraved line on a foot area is often enough to stop a glaze run.

 

best,

Pres 

Thanks, Pres, for the tips. I imagine even with nitrite-bonded silicon carbide shelves, these are good practices to always keep in mind. I really like this idea of using bevel undercuts and catch lips or engraved line….I’ve not tried that yet before. Any experience or thoughts on cookies? I just saw a video on them the other day and am intrigued…

Edited July 3, 2022 by moonari

[Bam2015]

Instead of starting a new thread re: kiln shelves, I figured I'd resurrect this one. Any more recent thoughts or recommendations on what type or brand of kiln shelves to purchase? 

Thank you,

Betty

[Denice]

I bought Corederlite shelves for my new L&L kiln,  I was told then that they had fixed the warping problem.   I don't have enough firings on them to know if they warp.   I will tell you that I was disappointed that they were heavier than I expected.   You shouldn't have too much trouble lifting the regular 15 inch shelves.   You could buy a Corederlite shelf to use as your bottom shelf,  that is always the hardest one for me to pick up of the 20 inch shelves.    You can always work with half shelves,  some kiln loading instructions recommend using only  half shelves.   I bought the lighter shelves because I am 70 years old and thinking of my future  kiln loading and unloading.     Denice

[Mark C.]

I like the Bailey Nitrate bonded shelves -they are as good as the advancers -I have tested them now with a over 80 cone 11 fires and they are in every way the same if not better as the corners are nicely rounded.

I always buy the best shelves that never warp.

In my 50 years at this I have a stacks of what was best at the time-thick mullit shelves-silicone carbide -the 70s and 80s) -then 1 inch heavy english dry pressed (mid 80s) and then advancers and Baileys Nitrate bonded (early to mid 90s to present). Once you buy these you never buy another shelve and they save so much space and are so light.

[Mark C.]

On that note I just got a new to me Geil Kiln and shelve size is 14x28-baily has 5 in stock (I need more) They come from Germany and none are on order-so If say I bought 10 the wait is 2.5-3 months . Just another fly in the ointment.

since I live about as far away as both suppliers are the ship cost is a big deal.

Kilnsshelve.com  is working up a quote as well on advancers-they foam  smaller boxes and shipping is way less as it's UPS -Bailey is truck rate and 5 shelves  shipped Truck is $485 to me. -So the lesson is not what they cost but also what  the shipping and packing cost to see what the bottom line is.

Edited August 31, 2023 by Mark C.

[moonzie]

We have some whole 8-sided Cordierite kiln shelves that we used for both bisque and glaze firing at least 200 times with no warping or cracking issues.  I even had to cut a few down with a diamond blade since they originally went to a kiln with 2.5" brick and ours is 3". They've even been dropped a few times a few inches. I believe these are 5/8" shelves.

But going to Advancer shelves was a game changer for us. 90% of the time, if the glaze runs on a pot too much I can save it with the advancer shelf. On the older Cordierite shelves, even with kiln wash, I think I had about a 40% success rate of removing the pot without damaging it. Not to mention how light and how thin they are which is important in our little 2.5 cu ft L&L. In fact, it's better to not use cookies with the advancers. I like to experiment with glaze layering so I feel like they've already paid for themselves in saved wares!

One caveat... over time, the Advancer shelves WILL get stained over the course of many firings. And that stain will permeate other works. I tried the silicon carbide sanding wheels from Menards - nope. I even ordered some special silicon carbide wheels from Advancer. Those did better, but did not completely clean. What worked was a Bosch turbo diamond cup wheel (from Menards) on my angle grinder. It took some time, but it came out MUCH cleaner. Wear a respirator and hearing protection.

I don't use kiln wash on the Advancer shelves.

[Ja.Sc.]

Hi, I'm looking at a set of Nitride-Bonded Silicon Carbide shelves for my kiln for the obvious benefits.   I've got a two questions that are holding me up at the moment.

1. Is there any reason I can't do mixed shelving in a single firing.  I've got a Skutt 1227, so replacing all the shelves is a bit more expensive than I'd like to do at the moment, and there's only a few shelves that really need it.  

2.  For the crash cooling aspect.. How is crash cooling different than running a cone fire program where the kiln simply stops? Will I need to run a program to manage cooling with these?  I'll only ever be firing to cone 6.  

[Hulk]

Good questions.
My guess on question one, using heavier shelves in the middle could help with evening out the heat.

Question two, with less mass - the new shelves weighing considerably less than the old ones - the kiln should cool more quickly, and heat quicker as well.
How much faster? If you have notes on loads where the differences in total mass (wares + shelves + posts) match up, that could be a good starting point.

My notes indicate significant differences in time to target - more time when the load includes an additional level (two half shelves, plus six posts) and more wares - and significantly slower cool down as well.
 

I'm curious to see what others have to say.

Edited March 31 by Hulk
browsed the firing notes

[Ja.Sc.]

Thanks Hulk,  

I was running through all these threads late into the night trying to ingest all the separate factors for each shelf type, and weighing that against cost and my personal use scenario.  So there was a lot of tab hopping.  

It seems that standard cooling, where the kiln is off, and vent continues to run is within the range of acceptable cooling rates?  If anything it would still cool more slowly than using all silicon carbide shelves, right?

Crash cooling would be taking additional measures to increase the rate of cooling?  If that's the case, I don't think I'd need to be concerned, I'm not in a rush. 

I'm thinking the biggest potential for trouble would be having two shelves of different heat loads on the same level, potentially creating uneven cooling, also easily avoidable.  

Edited March 31 by Ja.Sc.

[Hulk]

Good questions.

Glaze fire, I'm dropping 100°F from peak, then holding there for half hour or more, kiln vent left on.

From there, controlled cool to 1850°F, with kiln vent still running, then I'm shutting down the heat and the fan. Maybe that top shelf cools more quickly than the middle and bottom shelves when the fan is left on, so, I'm turning it off when the heat is turned off at 1850°F - also, I typically load the top lighter.

I believe the cooling rate to be closely tied to the mass - how much weight of material is in the kiln, so, faster cool with less mass.
If your kiln has a controller, you might program the last ramp(s) to match your firing notes?

I'm curious about shelves of different thickness at the same level; my guess would be that they are more part of the overall "system" in terms of heat and mass, and hence the ware on the light shelf wouldn't cool off faster, but I don't know that for a fact.