Tips For Making Pottery
So, you want to get into making your own pottery, but have struggled. We have already covered the basics of how to make your own pottery and how to make it from clay that you made yourself.
However, with any skill there are tricks of the trade that the experts know that makes their success rate high or simply make the job easier. Here, we will highlight some of these pottery making tips and hints.
Clay is the fine particles of dirt. The smallest particles. Although the only difference between sand, silt and clay is the particle size it drastically changes the physical properties.
Sand for instance does not stick together very well, but clay (remember play-dough) does. So, we use clay to make pottery because we can sculpt it into a variety of useful shapes.
Clay also has the physical property of holding on to water really well, where as Sand does not. Water runs through sand whereas clay is used to line ponds so that the water cannot leak out. Quite different based solely on particle size.
Another difference between clay and silt and sand is that clay depending on its source, not all clays are identical, will experience shrinkage when it is heated in a fire or kiln.
This shrinkage is bad for a couple of reasons. One, you make a cup and it turns into a thimble. OK that might be a bit extreme, but ideally you want to be able to easily control the size of your bowls, jars, cups, etc.!
The second reason too much shrinkage is bad is because it will cause you pottery to crack and break and basically explode during the firing process.
How to deal with this? Adding grog, which is ground up pottery from your previous failed pottery attempts. Once fired the clay will not dissolve and the shrinkage has already occurred. So adding it to your next batch of clay in various amounts will limit the shrinkage and increase the success rate.
How much to add will be a trial and error endeavor.
To make pottery you do not need a spinning wheel that you may have seen before, for instance in the movie Ghost. That is one way to form cylindrical clay objects such as bowls fast and symetrical, but it is not required at all.
Another method is the rope method. Basically in this method you take your clay and on a flat surface you roll it into long thin cylinders. You know kind of like a rope. The thickness of the rope will be a little thicker than the bowl you are trying to make. The length of the clay rope will be ideally at least as long as the circumference of the bowl. You stake the ropes on top of each other one at a time to form the sides of your bowl and use your fingers to smuch the ropes into each other so that there is not distinction from the rope you just placed with the one that it was placed upon.
You might have to add water to your clay to get it to stick and act the way you want without breaking. So, add water a little at a time until it acts properly. You only want to add just enough water because you will need to get rid of this water later before firing.
Your clay will can be dried by just letting it sit for long periods of time. But clay holds water well and although the sides will dry the internals will hold moisture for a very very long time.
So drying before firing is required for success. If your clay isn't dried before firing, then your pottery will break every time.
The best way to dry your clay after it has been made into your cup or bowl is to expose it to heat. 15 minutes is NOT ENOUGH! If there is even one spot that has moisture remaining, then that trapped moisture during firing will turn to steam and be trapped in the wall of your bowl. The pressure will go way up as it turns from liquid to gas and the bowl will break to let out that internal pressure.
So place you pottery next to your cooking fire or heating fire and turn it periodically to expose all sides of the bowl/jar/cup to the heat. Do this for far longer than you think you need too. It can't be done to long so don't waste your work in making clay and forming it into useful objects just because you didn't dry it long enough. Haste makes waste.
Make you clay in batches. Test your clay by making a simple small bowl. WHEN it cracks add temper or grog to that batch of clay and do another test bowl. Repeat until the cracking and exploding no longer ruins your bowl.
If you continue to get your clay from the same area the amount of temper it requires will remain the same and these steps can be reduced or eliminated once you know how much temper you clay requires.
Not all clay is good clay. If you work with clay but the shrinkage and therefore the cracking and breaking is just to much it might mean your clay source sucks and you need to find a new source of clay.
Clay jargon. Not all clays work, plasticity (fat clay very plastic)! Make coil that will wrap around your finger. Too fat to sticky hard to work with. Too fat to much shrinkage up to 25%. Too lean and the clay will lack plasticity. Too lean test the rope of clay will not bend around your finger without cracking. Of course the clay must be moist to perform this test.
Again to do a plastisity test roll the clay into a long coil. Shape of a thin cigar. See if you can wrap it around your finger like a ring. The more it cracks and breaks the less plasticity it has. Clay can be too plastic or not plastic enough.
Over time you will learn what amount of plasiticity is desirable. If the clay is to fat (plasticity to high) it can be very sticky and very hard to work with. Or if it isn't plasitc enough you will have to add temper material. Typically this is sand.
To add temper you need the temper to be ground down to a sand like consistence or finer. Then work this evenly into your clay batch by using a lot of elbow grease to work it in like a backer rolling dough. It must be done so that the temper is evenly distributed and this takes time and effort.
Wet clays can be to floppy and won't hold a shape. Need clay that is in the middle of the spectrum. Want easy to mold but still holds its shape when wet.
Temper aka sand, grog or ground up pottery makes clay less plastic.
Purify your clay to remove larger particles to make it more plastic. Heavier particles drop out sooner than smaller particles. So dissolve your clay in water and pour off the water after some setteling has occurred. Then evaparate off the water you poured off to get your purified clay.
If clay is to soft (low wet strength) and will not hold shape. Mix in grog.
If clay is to firm mix in softer clay.
Over time you will learn what amount of plasiticity is desirable. If the clay is to fat (plasticity to high) it can be very sticky and very hard to work with. Or if it isn't plasitc enough you will have to add tempar material. Typically this is sand.
Over time you may learn how much tempar to add just from this test but for now I think it is best to make 3 test bowls with your new clay.
Add no tempar to one. Add 10% to the second. And add 20% to the third.
Another test you might want to consider is a shrinkage test. Make a small rectangle of clay about a 1/4 inch thick or less and let it dry after you have wet it. Let it dry for a few hours and measure how much it shrank. If it shrinks a lot, as much as 25% it will be horrible to use as everything will shrink and likely crack as well. Not all clay's are equal even when pure.
Fire your three bowls and hopefully one of them will be uncracked and without a lot of shrinkage. Now if that was the 10% tempar added then now you know how much tempar that source of clay needs and you can start making pottery with it.
When firing pottery in an open fire, your pottery covered in wood, it is a good idea to protect you pottery from the fuel by coving it with pieces of broken pottery. These broken pieces are called shards. If you ever decide to make a protective cover out of clay be sure to add extra sand or grog to the clay, more than normal, to make this cover extra durable and able to withstand repeated firings.
The shards protect the pottery from carbon in the fire which will turn your pottery black and it also protects your pottery from thermal shock. So for these reasons you should try to use pottery shards or some form of cover when firing your pottery.
I hope these tips speed your way up the learning curve.
However, with any skill there are tricks of the trade that the experts know that makes their success rate high or simply make the job easier. Here, we will highlight some of these pottery making tips and hints.
Sand for instance does not stick together very well, but clay (remember play-dough) does. So, we use clay to make pottery because we can sculpt it into a variety of useful shapes.
Clay also has the physical property of holding on to water really well, where as Sand does not. Water runs through sand whereas clay is used to line ponds so that the water cannot leak out. Quite different based solely on particle size.
Another difference between clay and silt and sand is that clay depending on its source, not all clays are identical, will experience shrinkage when it is heated in a fire or kiln.
This shrinkage is bad for a couple of reasons. One, you make a cup and it turns into a thimble. OK that might be a bit extreme, but ideally you want to be able to easily control the size of your bowls, jars, cups, etc.!
The second reason too much shrinkage is bad is because it will cause you pottery to crack and break and basically explode during the firing process.
How to deal with this? Adding grog, which is ground up pottery from your previous failed pottery attempts. Once fired the clay will not dissolve and the shrinkage has already occurred. So adding it to your next batch of clay in various amounts will limit the shrinkage and increase the success rate.
How much to add will be a trial and error endeavor.
To make pottery you do not need a spinning wheel that you may have seen before, for instance in the movie Ghost. That is one way to form cylindrical clay objects such as bowls fast and symetrical, but it is not required at all.
Another method is the rope method. Basically in this method you take your clay and on a flat surface you roll it into long thin cylinders. You know kind of like a rope. The thickness of the rope will be a little thicker than the bowl you are trying to make. The length of the clay rope will be ideally at least as long as the circumference of the bowl. You stake the ropes on top of each other one at a time to form the sides of your bowl and use your fingers to smuch the ropes into each other so that there is not distinction from the rope you just placed with the one that it was placed upon.
You might have to add water to your clay to get it to stick and act the way you want without breaking. So, add water a little at a time until it acts properly. You only want to add just enough water because you will need to get rid of this water later before firing.
Your clay will can be dried by just letting it sit for long periods of time. But clay holds water well and although the sides will dry the internals will hold moisture for a very very long time.
So drying before firing is required for success. If your clay isn't dried before firing, then your pottery will break every time.
The best way to dry your clay after it has been made into your cup or bowl is to expose it to heat. 15 minutes is NOT ENOUGH! If there is even one spot that has moisture remaining, then that trapped moisture during firing will turn to steam and be trapped in the wall of your bowl. The pressure will go way up as it turns from liquid to gas and the bowl will break to let out that internal pressure.
So place you pottery next to your cooking fire or heating fire and turn it periodically to expose all sides of the bowl/jar/cup to the heat. Do this for far longer than you think you need too. It can't be done to long so don't waste your work in making clay and forming it into useful objects just because you didn't dry it long enough. Haste makes waste.
Make you clay in batches. Test your clay by making a simple small bowl. WHEN it cracks add temper or grog to that batch of clay and do another test bowl. Repeat until the cracking and exploding no longer ruins your bowl.
Not all clay is good clay. If you work with clay but the shrinkage and therefore the cracking and breaking is just to much it might mean your clay source sucks and you need to find a new source of clay.
Clay jargon. Not all clays work, plasticity (fat clay very plastic)! Make coil that will wrap around your finger. Too fat to sticky hard to work with. Too fat to much shrinkage up to 25%. Too lean and the clay will lack plasticity. Too lean test the rope of clay will not bend around your finger without cracking. Of course the clay must be moist to perform this test.
Again to do a plastisity test roll the clay into a long coil. Shape of a thin cigar. See if you can wrap it around your finger like a ring. The more it cracks and breaks the less plasticity it has. Clay can be too plastic or not plastic enough.
Over time you will learn what amount of plasiticity is desirable. If the clay is to fat (plasticity to high) it can be very sticky and very hard to work with. Or if it isn't plasitc enough you will have to add temper material. Typically this is sand.
To add temper you need the temper to be ground down to a sand like consistence or finer. Then work this evenly into your clay batch by using a lot of elbow grease to work it in like a backer rolling dough. It must be done so that the temper is evenly distributed and this takes time and effort.
Temper aka sand, grog or ground up pottery makes clay less plastic.
Purify your clay to remove larger particles to make it more plastic. Heavier particles drop out sooner than smaller particles. So dissolve your clay in water and pour off the water after some setteling has occurred. Then evaparate off the water you poured off to get your purified clay.
If clay is to soft (low wet strength) and will not hold shape. Mix in grog.
If clay is to firm mix in softer clay.
Over time you will learn what amount of plasiticity is desirable. If the clay is to fat (plasticity to high) it can be very sticky and very hard to work with. Or if it isn't plasitc enough you will have to add tempar material. Typically this is sand.
Over time you may learn how much tempar to add just from this test but for now I think it is best to make 3 test bowls with your new clay.
Add no tempar to one. Add 10% to the second. And add 20% to the third.
Another test you might want to consider is a shrinkage test. Make a small rectangle of clay about a 1/4 inch thick or less and let it dry after you have wet it. Let it dry for a few hours and measure how much it shrank. If it shrinks a lot, as much as 25% it will be horrible to use as everything will shrink and likely crack as well. Not all clay's are equal even when pure.
Fire your three bowls and hopefully one of them will be uncracked and without a lot of shrinkage. Now if that was the 10% tempar added then now you know how much tempar that source of clay needs and you can start making pottery with it.
When firing pottery in an open fire, your pottery covered in wood, it is a good idea to protect you pottery from the fuel by coving it with pieces of broken pottery. These broken pieces are called shards. If you ever decide to make a protective cover out of clay be sure to add extra sand or grog to the clay, more than normal, to make this cover extra durable and able to withstand repeated firings.
The shards protect the pottery from carbon in the fire which will turn your pottery black and it also protects your pottery from thermal shock. So for these reasons you should try to use pottery shards or some form of cover when firing your pottery.
I hope these tips speed your way up the learning curve.
