Floating Blue and pinging

i think this is normal, and on a larger scale explains how we get earthquakes.

it's a temperature shock issue where pieces come out hot and the shock to colder temps causes these little glaze fault lines to fracture or ping. it's from cooling down in general.

i've had pieces ping for up to 2 weeks. i kind of like the sound. it's like having a chorus of pots talking to you in the room...

certainly glaze fit is involved. the shrink rate of the glaze is not matched perfectly with the clay body. however excessively thin pieces can also ping even with a glaze that fits well on a larger thicker pot.

perhaps this always happens to you but you just never opened the kiln at quite this temperature? therefore you didn't hear it before?

happy pinging!

steve

steve graber

I agree with the previous answer about temperature difference but thought I bring up another possible cause.

Have you used Standard clay #153 before at cone 5/6? I have had glaze fit problems with #153 in its lower range. The standard ceramic website now lists the clay range as 6-10 instead of 4-10. I have used the same glazes with other cone 6 clay bodies without the problems. (Not floating blue specifically but 5 different blues including two pre-mixed.) I have also varied the ramp down rates and opening temperatures without much success.

If your ware is functional you definitely need to check for pinholes with sharp edges that could trap bacteria and that the clay is vitrified. (I have a collection of vases that slowly leak.) Initially I was drawn to #153 because I could use it at cone 6 in my electric kiln and cone 10 in the gas kiln but I have given up using it in the electric kiln.

On the other hand, #153 does beautifully when I fire it at cone 10 in a reduction environment. While not specifically designed for Raku I have used it without problems - so far it has handled the thermal shock.

I have had a lot of success with Standard Ceramics cone 6 Grolleg Porcelain - I think it is #365. (I realize it is a totally different clay body from #153 but still Standard Ceramics.)

I don't know if this information helps or not. Good Luck.

- Kobey

CNB wrote:

Thank you both for posts to my problem. Kobey this is the first time that I used #153 at cone 5. This is the only glaze that I have calling for that cone. Mostly I fire to cone 6 and I never got pinging at cone 6 with this clay and the other glazes. Floating Blue did ping at cone 6 but only a few times.

I have decided to switch clays and use #153 for cone 10 firing. Have you any other experience with cone 4-6 Standard clays? Can you or anyone else recommend Standard clays that are best for cone 6 glazes. I want to veer away from clays that have that wide range of firing. Standard Clay is what is available to me so I want to stick to that brand. Kobey you are correct Grolleg Porcelain is #365. Do you throw with this clay? I've been wanting to try porcelain again so I will get a box of this to play around with. Thanks. I would also like to get cone 6 stoneware clay and they have several. Much appreciation, Crystal

| > Here is the recipe I used: | > Nepheline syenite 47.3 | > Gerstley borate 27 | > Silica 20.3 | > EPK 5.4 | > Red iron oxide 2 | > Cobalt oxide 1 | > Rutile 4 | > Bentonite 2 | >

| > Thanks, | > Crystal | > USA | >

| >

Sorry to take so long to get back to your question. The only other cone

Years ago I tried 182 or maybe 181 but I fired it to cone 10 not cone 6.

I have recently moved away from Pittsburgh PA (USA) and therefore Standard Ceramic clays are no longer as economical. I still may have

Good luck, Kobey

CNB wrote:

That's O.K. Thank you. I will keep the 365 Porcelain in mind. I do want to work with porcelain in the future. I had some clay 153 that I bought a while back and I'm going to try that with the Floating Blue and see if it helps. I decided I'm going to buy several of the cone 4-6 clays and see which one I like best. I want to try one that is reddish and see how I like it. I've never worked with a red toned clay yet. I have used the 182 and it's nice but I like a buff colored clay better. The 182 is a great throwing clay though. Someone in the area that you are moving may carry the clays that you use. I get my Standard Clay from Gulfport, Mississippi (USA). Good luck in your move and thanks for your reply, Crystal

| > I have decided to switch clays and use #153 for cone 10 firing. Have you any | > other experience with cone 4-6 Standard clays? Can you or anyone else | > recommend Standard clays that are best for cone 6 glazes. I want to veer | > away from clays that have that wide range of firing. Standard Clay is what | > is available to me so I want to stick to that brand. Kobey you are correct | > Grolleg Porcelain is #365. Do you throw with this clay? I've been wanting to | > try porcelain again so I will get a box of this to play around with. Thanks. | > I would also like to get cone 6 stoneware clay and they have several. | > Much appreciation, | > Crystal | >

| > | > Here is the recipe I used: | > | > Nepheline syenite 47.3 | > | > Gerstley borate 27 | > | > Silica 20.3 | > | > EPK 5.4 | > | > Red iron oxide 2 | > | > Cobalt oxide 1 | > | > Rutile 4 | > | > Bentonite 2 | > | >

| > | > Thanks, | > | > Crystal | > | > USA | > | >

| > | >

| > | | >

| >