[QotW: How do you store your clay?]

1 hour ago, Callie Beller Diesel said:

@Babs my supplier does price breaks by box rather than by round numbers of weight, so I am getting some bulk discounts with that number. I have done group orders in the past, but I don’t have the bandwidth at the moment for herding cats like that. Part of the reason I get quarterly amounts is because my supplier is in the city and the manufacturer is about a 3 hour drive. so it’s more convenient and I get clay at the right consistencyAll things considered, the cost of my clay is one of my more affordable business expenses. 

Not me Callie, maybe  @Bam2015 not a cat herder or kittens in basket keeper here either

[Why my clay acts like this?]

5 hours ago, Tina01 said:

No, I mixed both in dry form then with water. after stirring well pour it on that black fabric to draw excess water and sat overnight. this was the next day result, dry on surface but wet underneath. scrub that from fabric and that was the final result in the video.

Even some ordinary mud is more clay like than that.  couldn't even make a thick coil out of it as it was breaking apart. 

Leave it to slake overnight , try adding a little vinegar, stir then put IN cloth to drain. Then wrap and leave. Wedge next day.  May be different. If this is the clay which you wrapped around your finger, plasticity should not take much bentonite to sort. 

Worth a try. 

[Why my clay acts like this?]

1teaspoon aporox 30gms : 250 gms 12%. Quite a bit, was it mixed with water first?

May need to rest it before wedging if you added the powder of bentonite.

[handles heating up in microwave after several years of not doing so!]

Could dishwasher treatment have gradually affected the glazes?

[Why my clay acts like this?]

https://www.instagram.com/p/CifWcsnugTo/?igshid=YmMyMTA2M2Y=

This guy says some where some clay he works with us up to 50% sand!

Have to change expectations, he is adapting how andxwhat he makes to suit the clay body imo

 

[Why my clay acts like this?]

46 minutes ago, Tina01 said:

Thank you. Yes I  knew that, those were what didn't pass the sieve for a test, therefore I washed them to find out what they are actually and whether they are beneficial or harmful, in order to find out if I have to sieve all the dry powder I've bought or not.

 

So the grit you have washed out is from clay powder you bought?

Might be essential for hand building and sculputural forms.

On the other comments, cracking as shown when rolling is quite common.

Rolling stretched the ribbing over really helps with my clay.

[Why my clay acts like this?]

Btw if you are sieving and washing, you msy be throwing away the fine particles you require for plasticity

[Why my clay acts like this?]

That cracking at edges when rolling shortish, i.e. low plasticity clay body, is common.

Releasing clay between rolls, rolling in different directions,

rolling in a gentle manner can alleviate this.

From your wedged slab, cut a slice close to the thickness you require, the less handling the better imo. i.e. less stretched

Clay may need to be  a little wetter.

Try rolling on a canvas.

Just thoughts.

[Any ideas why these mugs look streaky after holding liquid?]

17 hours ago, TaraB said:

Thanks for taking the time to reply, Bill. I see what you’re saying with the glaze… It’s just odd because I’ve used this same glaze several times before and never had this issue. It’s not a stain as such, because I get the same streaking in the remaining mugs with plain cold (or hot) water. It does seem to be a vitrification problem. I have had them filled and sitting on paper towel for the past few hours and I’m starting to notice very slight dampness on the paper . Unfortunately I cannot retire them as they have gold lustre which I am assuming will not do well in hifire!? 
Can batches of the same clay vary? ie, could this particular bag of walkers 10 be slightly different to my previous bags? I am so stumped as to why this has happened. 

When did you buy your previous batch?

Walkers did change sites of quarrying. But issues stated above re vitrifying and glaze maturity hold water if you'll pardon my poor choice of phrase

[Why my clay acts like this?]

4 hours ago, Tina01 said:

I want to try both, however now that I've found a consistent type source, need to know what am I doing wrong and what to tweak. 

@Babs says roll a coil around your finger, shouldn't crack. 

I did so and it was relatively smooth, but when making the slab it's all cracked at the bottom surface. 

I know there might be many factors involved, but want to know most probable ones. 

e.g. does it need to be mixed with bentonite, if so, how much? does it need more water? more wedging? adding temper (cattail)? should I sieve it? should I set it aside to rest after mixing with water? or should I just work on a non water absorbent material rather than wood? or something else? 

 

If your clay was my recycled,or like a tonneI bought behaving like yours, I would add " fines" which can get lost  after throwing pots. 

@glazenerd has a magic solution, and or add bentonite.

But it is hard to judge without hand on it.

If the board you are working on is very absorbent, your clay may need to be wetter  , or you could roll on a canvas or a cloth.....

Areyou releasing the clay from the board during the rolling process. Compress that surface by running ribs on it.

You plate mold should be coated with a releasing agent, green soap, oil sprayed. It looks like it has caught on the rim where it has cracked on left hand side. This would stress your whole pot.

Your plate may need slow drying. It is shrinking quite a lot.

As glazenerd wrote, change one thing at a time.

I think you are closing in on this, keep testing. 

Don't prejudge  on the "Masters " .they got where they are because they observe and test ad infinitum. Don't have to pick up all they say   just what is relevant to you. All blinkers off in this game

[Why my clay acts like this?]

4 hours ago, suetectic said:

so mullite(from kaolin) is a grog while kyanite is a temper? nvm both are ultimately derived from kaolin if I understand correctly so both can be grog if ceramic includes kaolin.

I want to be able to explain this in simple terms in possible.

I should have probably suggested previously that temper 'also' includes to help indicate temper includes refractory and non-refractory material.

You are overthinking this I feel.

you have a clay body .

It is not the best to work with.

You add a temper to it, or temper it by

adding the substance of your choice, or want to test,.

this substance is the temper which can be a grog or any other substance you find helps you to work with the clay body.

Ceramics is difficult enough without getting bogged down in the semantics imo.

[Glazing pottery like spoons]

Stilts will work best at low to midfiring temps imo , a little grind will remove rough spots.depending on design you can get away with just the end of underside of handle and a tiny area of belly of spoon being coated with resist and rest glazed. 

[Bisque Temperature]

If you are going to glaze those pieces, no , as those pots won't accept the glaze after reaching the glaze temperature. Those pots could be painted....

Also as greenware you would have to alter the start of your glaze firing. So use schedule for a bisque firing until 600 deg Çelcius then fire as usual for a glaze firing

[Problem with royal blue underglaze (cobalt)]

That blue can be problematic. I used to mix a bit of frit into it, you'd have to test, as it doesn't meld with the glaze at certain thicknesses 

[Problem with royal blue underglaze (cobalt)]

You may have unevenly dried greenware at the point of application and so inadvertently getting thick areas where the clay grabs the moist underglaze..

I spray the whole pot with a light mist of water before starting to apply underglaze.

It looks like you are brushing in lots of directions. Perhaps applying a resist to your flowers would enable you to then brush across your plates and get a more even application.

[Problem with royal blue underglaze (cobalt)]

That purpling crystals are somethkng I get with a glaze containing Magnesium Catbonate. The effect of different fluxes I guess. The cobalt may have been thicker there where it is occurring on your dish. Metallic usually comes grom overload of the metallic element in the underglaze

The bleeding is 

Bit thicker glaze?

Glaze and so underglaze moving at that temp?

[Firing a Sealed Shape]

2 hours ago, Ben xyz said:

The key sounds like it’s making sure the piece completely dry before firing (which takes longer than usual, due to the enclosed area). Thanks for the responses.

And a slow candling and slower ramps at start of bisque firing

[New skutt kiln - Best program for bisque firing]

Had a sculptural piece  of an old friend's, sat around for years , still exploded,  damp inside.

Explosion...water, cracking , another story or two.

[Can I re fire pottery that did not reach vitrification?]

Yeh, I haven't witnessed that.  Water would be out of it before glaze melt and sealed off escape routes?

Test and see I guess

[Milk Frother Changing Nature of Glaze?]

I have a glaze which likes to form bubbles when stirred and unless I spray hairspray to dispel them, or fettle them, they will affect the surface of the glaze but not going to the internal frothing of a lava glaze

[Can I re fire pottery that did not reach vitrification?]

4 hours ago, Rae Reich said:

Does anyone else think that a leaky, glazed low-fire piece that has been wetted will not suffer in a refire? I think there might be some glaze popping off, possibly some cracking or breakage, even if refired to the same temp.

One way to tell …

OP firing to cone 6 with cone 7 half way down. CKay maturing at 1250 d C so not a low fire imo.

@Anna M are your pots glazed all over? Which pots did not leak?

Could weigh totally dry pot, soak totallly overnight and weigh to test absorbency %

[Why my clay acts like this?]

Crack the dried clay down as much as possible snd then slake.

Sand is your prob.

If already a handbuiling clay ,dnt need it. Coil abit of clay and bend the coil around your finger, shouldn't  crack.

[Why my clay acts like this?]

The mold ,steel bowl  , needs to be coated with something to prevent clay from sticking to it as it dries.

Strips of damp newspaper, plastic wrap, green thick dishwashing liquid etc.

Oh! a hump mold  need to get that clay off there asap. Clay shrinks, mold doesn't

How did you wet the clay  down?

Was the clay previously thrown into pots? Can lose fine particles which make clay plastic.

Make a slurry of clay   leave for a couple of days, spread out on plaster board to dry , wedge and see if it is better.

May need some bentonite to increase plasticity.

Do you know what clay it is?

[Can I re fire pottery that did not reach vitrification?]

I'd wait for your new bag of clay and when you get to glazing the new pots, put one of your unvitrified pots on a waster piece of clay, no need to pre bisque but could to feel safe. 

Put in hot spot in kiln

The extra heatwork from refiring may nudge it over the line  or may need to get that cone 7 over

What glazes on pots which leaked  ?variety or the higher maturing?

Might save you an unsuccessful firing.

Could put all on waster saucers  and risk a melt and run of glazes. Would be a midfire clay which would be better I am sure.

 

[Can I re fire pottery that did not reach vitrification?]

What cone did you fire to?

What cone does your glaze mature at?

What does it say on your bag of clay re  cone that clay requires for vitrification?

Just that if glaze already on pot is a lowfire glaze and you need to go to a higher cone, your glaze may run off pot onto shelf. Re drying pot not necessary , justlike you can put pots just glazed straight into kiln for glaze firing.