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meisie

Unwanted Crackling

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I am a beginner at glazing and firing and so far so good but I was wondering if anyone could help me solve a problem. I have several types of clay and one of them is from a local clay dealer it's a white throwing cone 6 clay and I love working with it. I have been glazing it with clear. I don't yet have the ability to make my own glazes so I have bought several commercial glazes all from Amaco. The clear is also Amaco, Sahara. It works well on the Laguna clays and does not crackle but when used on the white clay it crackles every time. It's also easy to see it sits on top of the piece without bonding to the clay. I know from reading my Mastering Cone 6 glazes that the glaze is a poor fit for the clay (or the other way round) but the question is what glaze then should I be looking for? What should I know about this clay before I buy a glaze? What questions do I need to ask the clay manufacturer? And how do I match up clays with the proper glazes. I asked these questions elsewhere but go no response so perhaps there is no easy answer. but thanks any way :-)

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I am a beginner at glazing and firing and so far so good but I was wondering if anyone could help me solve a problem. I have several types of clay and one of them is from a local clay dealer it's a white throwing cone 6 clay and I love working with it. I have been glazing it with clear. I don't yet have the ability to make my own glazes so I have bought several commercial glazes all from Amaco. The clear is also Amaco, Sahara. It works well on the Laguna clays and does not crackle but when used on the white clay it crackles every time. It's also easy to see it sits on top of the piece without bonding to the clay. I know from reading my Mastering Cone 6 glazes that the glaze is a poor fit for the clay (or the other way round) but the question is what glaze then should I be looking for? What should I know about this clay before I buy a glaze? What questions do I need to ask the clay manufacturer? And how do I match up clays with the proper glazes. I asked these questions elsewhere but go no response so perhaps there is no easy answer. but thanks any way :-)

 

 

You should be able to get the information from the dealer that you bought the clay from and tell them what kind of problems your having. Are you sure the clay is Cone 6 not 06 or you may have gotten a bad batch of clay which happen to me once. Clear glaze is pretty forgiving when it comes to problems other glazes aren't, I would start with the dealer to eliminate the clay as the problem. Denice (Wichita, KS)

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You are right ... there is no easy answer.

 

The Amaco Sahara clears HF-9 and HF-10 are Cone 5 glazes. I have found them to be pretty forgiving over different kiln temps, but maybe not with your clay body.

 

The fact that you say it sits on top of the clay makes me wonder if your clay is a low fire clay body and has been overfired. Did the glaze absorb at all when you applied it or did it stay runny for a while?

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yap, it's difficult enough to remedy the crackle, because i have been working many experiment for remedy the crackle. There are little progress, but not satisfied me. The point is the stresses of body and glaze must proper or match. You can try fire the glaze more or less than before, may be fired at cone 5 or cone 7.

 

Good luck:rolleyes:

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You are right ... there is no easy answer.

 

The Amaco Sahara clears HF-9 and HF-10 are Cone 5 glazes. I have found them to be pretty forgiving over different kiln temps, but maybe not with your clay body.

 

The fact that you say it sits on top of the clay makes me wonder if your clay is a low fire clay body and has been overfired. Did the glaze absorb at all when you applied it or did it stay runny for a while?

 

 

Thank you all for your replies I guess I really need to find time to call the manufacturer and see whats up. It's just that they can be a bit cranky sometimes. The glaze went on just like all the other glazes and there was no problem with application so again thanks and we'll see what happens.

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I am a beginner at glazing and firing and so far so good but I was wondering if anyone could help me solve a problem. I have several types of clay and one of them is from a local clay dealer it's a white throwing cone 6 clay and I love working with it. I have been glazing it with clear. I don't yet have the ability to make my own glazes so I have bought several commercial glazes all from Amaco. The clear is also Amaco, Sahara. It works well on the Laguna clays and does not crackle but when used on the white clay it crackles every time. It's also easy to see it sits on top of the piece without bonding to the clay. I know from reading my Mastering Cone 6 glazes that the glaze is a poor fit for the clay (or the other way round) but the question is what glaze then should I be looking for? What should I know about this clay before I buy a glaze? What questions do I need to ask the clay manufacturer? And how do I match up clays with the proper glazes. I asked these questions elsewhere but go no response so perhaps there is no easy answer. but thanks any way :-)

 

 

 

Glaze fit can be a problem when you are using clays and commercial glazes not formulated by the same manufacturer. It stands to reason that the manufacturer formulates and tests glazes for and on their clays. Try using Amaco glazes with Amaco clays. Standard glazes with Standard clays, and Laguna clay with Laguna glazes, etc. Under glazes can be used on all but, test them anyway just to be sure. Above all read, test and make notes about the results.

 

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Thank you and of course that makes perfect sense. I've made glaze before in a class but I'm not really equipped to do it at home. Called the place where I bought the clay and as I suspected he was not very helpful. It's like pulling teeth to get any info from him. He has a clear glaze there and I think I'm going to get that and hope for the best. If it does not work I guess I'm going to have to call it a wash and try some other clay. There is so much I don't know and am very frustrated at the moment so if I sound bitchy it's just a bad day.

 

 

Glaze fit can be a problem when you are using clays and commercial glazes not formulated by the same manufacturer. It stands to reason that the manufacturer formulates and tests glazes for and on their clays. Try using Amaco glazes with Amaco clays. Standard glazes with Standard clays, and Laguna clay with Laguna glazes, etc. Under glazes can be used on all but, test them anyway just to be sure. Above all read, test and make notes about the results.

 

 

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Thank you and of course that makes perfect sense. I've made glaze before in a class but I'm not really equipped to do it at home. Called the place where I bought the clay and as I suspected he was not very helpful. It's like pulling teeth to get any info from him. He has a clear glaze there and I think I'm going to get that and hope for the best. If it does not work I guess I'm going to have to call it a wash and try some other clay. There is so much I don't know and am very frustrated at the moment so if I sound bitchy it's just a bad day.

 

 

Glaze fit can be a problem when you are using clays and commercial glazes not formulated by the same manufacturer. It stands to reason that the manufacturer formulates and tests glazes for and on their clays. Try using Amaco glazes with Amaco clays. Standard glazes with Standard clays, and Laguna clay with Laguna glazes, etc. Under glazes can be used on all but, test them anyway just to be sure. Above all read, test and make notes about the results.

 

 

 

 

 

Ceramics supply catalogs, books and magazines can give you lots of information on clays. Some of the catalogs show pictures of the fired clay samples in oxidation as well as in reduction in their catalogs. Others offer a chart about their clays and the specific working properties, which is very helpful before you make a purchase.

 

What kind of work session do you employ are you impulse driven or project driven? The difference between the two is the planning. In my early days of pottery I was impulse driven. I would sit down at the wheel to see what happens. I would choose glazes I liked in a catalog and then figure out what I wanted to use them on or sometimes choices would be made based on which glaze I had the most of. There was neither rhyme nor reason. I was just 'beboppin' and scattin' '. Sometime after that I began planning but still 'scattin' a little. Then later I took a definitive stand and began approaching the work more methodically by planning. Now after 36 years it is all planned to the last detail.

 

. I start with a vision and work from that perspective; which of course involves a bit of research now and then, though not as much as I needed years ago. I do a check list of what I will need to accomplish the piece or pieces. I write it all out.

 

I still 'bebop' a little when I am trying out a different technique of some kind. But when I want to be deliberate I plan it all. I know which manufacturers' clay I want, how I will form it, what under glaze or glaze I will use and how I will photograph it. But this has come about through all of the years of frustrations, trials and errors.

 

Frustrations still occur from time to time. That’s when I clean up, make bread, go for a walk, or watch Casablanca. The problem never seems to loom so large the next day.

 

 

 

 

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Thank you and of course that makes perfect sense. I've made glaze before in a class but I'm not really equipped to do it at home. Called the place where I bought the clay and as I suspected he was not very helpful. It's like pulling teeth to get any info from him. He has a clear glaze there and I think I'm going to get that and hope for the best. If it does not work I guess I'm going to have to call it a wash and try some other clay. There is so much I don't know and am very frustrated at the moment so if I sound bitchy it's just a bad day.

 

 

Glaze fit can be a problem when you are using clays and commercial glazes not formulated by the same manufacturer. It stands to reason that the manufacturer formulates and tests glazes for and on their clays. Try using Amaco glazes with Amaco clays. Standard glazes with Standard clays, and Laguna clay with Laguna glazes, etc. Under glazes can be used on all but, test them anyway just to be sure. Above all read, test and make notes about the results.

 

 

 

 

 

Ceramics supply catalogs, books and magazines can give you lots of information on clays. Some of the catalogs show pictures of the fired clay samples in oxidation as well as in reduction in their catalogs. Others offer a chart about their clays and the specific working properties, which is very helpful before you make a purchase.

 

What kind of work session do you employ are you impulse driven or project driven? The difference between the two is the planning. In my early days of pottery I was impulse driven. I would sit down at the wheel to see what happens. I would choose glazes I liked in a catalog and then figure out what I wanted to use them on or sometimes choices would be made based on which glaze I had the most of. There was neither rhyme nor reason. I was just 'beboppin' and scattin' '. Sometime after that I began planning but still 'scattin' a little. Then later I took a definitive stand and began approaching the work more methodically by planning. Now after 36 years it is all planned to the last detail.

 

. I start with a vision and work from that perspective; which of course involves a bit of research now and then, though not as much as I needed years ago. I do a check list of what I will need to accomplish the piece or pieces. I write it all out.

 

I still 'bebop' a little when I am trying out a different technique of some kind. But when I want to be deliberate I plan it all. I know which manufacturers' clay I want, how I will form it, what under glaze or glaze I will use and how I will photograph it. But this has come about through all of the years of frustrations, trials and errors.

 

Frustrations still occur from time to time. That’s when I clean up, make bread, go for a walk, or watch Casablanca. The problem never seems to loom so large the next day.

 

 

 

 

 

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