Are You in Control of Your Production Process?

Description

Potters often run operations that are on the edge of control tolerating production and ware problems that industry would not. However ethics will sooner or later demand a better knowledge of process and materials.

Article

Have you ever blissfully ignored the possible consequences of less than ideal production methods, then acted surprised when a day of reckoning came? When forced to look previous mistakes in the face, it often turns out that past problems, which appeared small and unrelated, have come together to cause major headaches.

A production facility cannot be operated on luck; it must be run with an understanding of the materials and processes. Each facet of a production line has a set goal and is like a highway. But remember, for every mile of highway there are two miles of ditch! If you understand and control the processes and materials, then you proceed down that highway in a relatively straight line. If not, you zig-zag more and more until you hit the ditch. Typically, a problem has a dizzying array of contributing factors and the 20:20 vision of hindsight usually testifies to how many things could have been done differently.

When things are going well, it is a joy to unload the kiln. But when a glaze problem hits, "crisis management mode" kicks in and everyone suddenly becomes very interested in glaze chemistry! There is a much more direct relationship between glaze chemistry and fired results than between glaze recipe and fired results. So if you are having a problem with fired ware, then chemistry might be an important factor in solving it properly.

How close are you to encountering a ceramic related problem or product liability that could endanger everything you have worked for. It is typical for small-scale ceramic operations to have much less than 'complete control'. For example:

Often no testing is done on incoming clays, clay bodies, glazes and glaze materials.
Kilns are of the hobby type or home-built. Firing is often too fast and lacks consistency from firing to firing.
Glaze recipes have been gleaned from books and other potters and have been put into production on the merits of their visual properties only. For example, I estimate that 90% of glazed ware made by potters does not have a properly fitted glaze thus severely weakening the ware (only extreme cases display crazing and shivering right away).
Glaze recipes are often leachable and contain toxic metal oxides that can be released.
Production facilities lack space and drying is thus 'hurried' and drier facilities are not only not available but their true value is not appreciated.
Potters are often untrained in technical areas of production. It is very common for people to overestimate their ability to produce both quality and quantity of a given line of ware.

Potteries stretched to the limit are on the 'edge of control' already and are ill-equipped to deal with unexpected problems and often unable to diagnose the true cause. Many tend to be stuck in an "I've always done it this way and it worked before" way of thinking.

Some think that the pottery and ceramic slip-casting businesses are similar. But they are not. In the ceramic shops everyone uses the same clay body, the same slip recipe, the same jars of glaze, the same temperature, the same kilns. The big manufacturers of suppliers for that industry have a 'level playing field' and they have worked out the problems so that people without ceramic knowledge can make ware successfully. But in pottery the only thing that is the same is that everyone does it different.

To reduce your liability if someone is hurt with your ware you must be able to demonstrate that you are qualified, conscientious about making safe ware (i.e. testing, consulting experts) and that you deal quickly with complaints.

I don't have any magic solutions but here are a few suggestions to help you 'protect your butt'.

Increase your knowledge of your materials and process

If you can answer the following questions then you will be a better position to solve problems related to each.

Why is my glaze matte? Is it high alumina, high magnesia, fluid crystalline?
Is my ware strengthened or weakened by my glazes?
Am I using one or two base glazes that I understand or am I struggling with fifty that are always on the edge of control? Do I know why each material is in my base glaze? Do I know how to adjust the glaze for temperature, color?
What is the porosity of my clay body at the temperature I fire at? What is it one cone higher and lower?
Do my glazes fit? Will they pass a hot-water cold-water test? Do I know how to adjust their expansion?
Are my glazes leachable? Do I know why?
Are my glazes hard? If not do I know why and how to improve them?
Are my glazes volatile in any way? Do they tend to run, blister, devitrify, pinhole?
Am I using the right clay body? Why?
Am I firing at the best temperature for the type of ware I do?
Am I using quality materials or cutting corners by using cheap, inconsistent ones?
Do I have a good relationship with my prepared clay body manufacturer? Do I call them at the first sign of trouble or struggle until things are out of control?

A change in thinking

You might feel that doing things one way has always worked, but did it really? Maybe your ware has been deficient in a certain way all along and you didn't see it. Maybe you have been lucky in the past, maybe your way of doing things doesn't 'scale up' well, maybe the only thing that kept you from falling off the edge was luck. Pottery is a very complex business, no one person can know it all. Be ready to accept suggestions and but get the reasoning behind them so you know why you do things the way you do.

Don't bite off more than you can chew

We have all had to 'eat crow' after being unable to make pieces we promised someone because our way of doing things just did not work with that type of ware? Never commit to doing a type of product unless you've actually done it already and done it over a period of time. Moving to another temperature range, for example, is a really big deal, don't underestimate it.

Recognize your responsibility

Be very cautious about making cookware or ware to be used on top of the stove. No matter what anyone says, an ordinary clay body is just not good enough for ware that must withstand sudden changes in temperature. You can be open to liability if someone expects the same thermal shock performance from your products as Corningware and then burns them self. Contact your clay supplier to get a body intended for this, but be ready to make some compromises in order to use it.

Don't be smug and think that because your stuff is beautiful you are exempt from concerns and hardness, strength, porosity, leaching, thermal shock resistance, chip resistance, glaze fit of your product. Some of these relate to safety concerns for your customers, all relate to the your reputation and that of the entire pottery community. Simple tests are within your reach to address these matters and you should know about them.

Related Information

Links

Projects	Tests
Glossary	Leaching Ceramic glazes can leach heavy metals into food and drink. This subject is not complex, there are many things anyone can do to deal with this issue

By Tony Hansen
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