Centering your clay is one of the most important parts of throwing pottery on the wheel. You want the walls of your pottery to have the same thickness, and you don’t want to struggle for what seems like forever to get your clay centered. Every new potter and even some who have been around for many years will struggle or encounter some kind of problem when centering their clay. So, I decided to make a list and came up with 11 centering problems that either I encountered or observed other potters having problems with. Here are the ways to avoid those 11 centering problems that you will eventually encounter.
1. Selecting the Wrong Clay
If you are struggling with your clay and it feels like you are throwing sandpaper, you may be using clay that is made more for handbuilding then throwing. Technically you can use any kind of clay for throwing on the wheel, but some types can be stiffer and harder on your hands than others. As a rule, you want to have a smooth clay. For beginners, it’s best to choose a clay with a bit of grog or sand in it because it takes longer to center and bring up the walls of the clay. If the clay is too smooth and you play with it too long, it will collapse. I found Amaco Stoneware 46 Buff works the best for me. It is so forgiving on the wheel and one of my favorite clays. I can even hand build with this clay. You can check out My Top Clay Picks; they are all good for throwing on the wheel.
2. The Clay is too Hard
There are several reasons your clay would be hard. If you get your clay balls ready and let them sit out too long, they will get hard. It’s important to cover your clay balls with a damp towel or put them inside a plastic bag. Your clay can also dry out when stored for a long time. Slice your clay in sections, spray some water on it, and wedge it really good. That should moisten your clay. If your clay is still a bit hard, you can wheel wedge (Wet your clay, cone it up on the wheel, and press it down.) This can be done several times to introduce more water into your clay.
3. Not Enough Water on your Clay
If your clay feels dry against your hands as you’re centering, you don’t have enough water or slip (water and clay mixed) on your hands. Slowly take your hands off and dip them in water or you can hold your sponge in your right hand and slowly squeeze the desired amount of water onto your clay. Make sure you don’t squeeze too much water at once. This technique helped me a lot when I was learning how to center because I didn’t have to take my hands off the clay to dip in the water.
4. The Clay Is Too Wet
There are two ways your clay can get to too wet. Either your clay starts out that way, or you are adding too much water because you’re taking too long to get it centered. If this is the case, you can try to wedge some of the excess moisture out, or you can lay your clay on a drying board and wedge out a new piece.
5. The Clay Was Not Wedged Properly
Many potters especially beginners do not like to wedge their clay, and there is a good reason for this. Most of us have never wedged clay before, and it’s not the most fun or the easiest part of pottery making, but it’s an essential part. Some self-taught potters and even some experienced shortcut takers will cut the clay out of the bag, pat it in a ball, and start throwing. Many don’t see a problem with this but can have a hard time centering and think it has nothing to do with skipping the wedging process. When I did the same thing, I found my clay was harder in spots and more difficult to center because the moisture was not consistent throughout my ball of clay. Trying to save time and cut corners didn’t work because I ended up spending more time trying to center clay that was not smooth and homogenous throughout. Wedging your clay well removes small hard spots, and you will feel a more uniform consistency throughout your clay while throwing. I found that in some new bags of clay the edges were hard and the middle was soft, and in other cases the middle was hard, and the edges were soft. Bottom line is centering will be much easier with a well-wedged ball of clay.
6. There Is an Air Pocket in Your Clay
Fighting to get my clay centered was not a fun activity. I finally gave in and called the instructor over for help. The ball of clay still refused to center. The instructor knew there was an air pocket in the clay. She said if the air pocket is big enough your clay will never center because air is lighter then clay and will continually throw your clay off center.
If this happens, take the clay off your wheel, wedge another piece, and start over.
Here are two ways to avoid air pockets
1. First is to make sure you wedge properly, if you don’t you can actually put air pockets in your clay instead of taking them out.
2. Second is to make sure the clay you put on the wheel is rounded and not flat on the bottom. If it’s flat your chance of getting air stuck in between the wheel and clay goes way up.
7. Your Elbows Are Up in the Air
When I started centering I would hear the instructor say watch your arms. I looked and there were my arms up in the air. Well, how did they get there? It’s funny when you are concentrating on getting this ball of clay perfectly centered; you tend to forget what your other body parts are doing. Keeping your arms anchored to your leg or the side of your body helps a lot — that way the clay has nowhere to go except where you want it. Also, make sure you are using the heal of your hand, and your wrist is bent.
8. Pushing Too Hard on Your Clay
When I started centering I was pushing so hard the clay was continuously going off center. My clay had nowhere else to go because I was pushing down with one hand and too far to the center with your other hand. It reminded me of when I started driving and had a death grip on the steering wheel. Well, the same with my clay. It’s best to transfer the pressure by using your whole body and let your hands do the steering. When you do this, it is easier on your hands, arms, and back. I found it will help a lot if you stay firm but relaxed. Apply steady pressure at the 7 to 8 o’clock position and feel the motion of the clay.
9. Avoid the Mushroom or Volcano Effect
Mushroom – While centering your clay make sure you are not creating a mushroom shape. This will create a pocket where slip and air can get trapped. If it starts to look like a mushroom you want to cone up your clay, then push down like a karate chop on the side and keep your anchor hand firm, so you don’t form a mushroom.
Volcano – If your clay starts to look like a volcano, air and slip can get trapped on the top.
Use one hand to brace the side and karate chop your other hand on the top side of your clay until your volcano goes away. Make sure your karate chop is on an angle.
10. Your Wheel is Moving Too Slow
When your wheel is going too slow, you will find your clay is moving you around more than you are moving the clay. When you speed up the wheel, you will find you have better control over centering the clay. You want to speed the wheel up to med-high or all the way to high. I found the highest speed works best for me. Once your clay is centered you can slow your wheel down to make your pottery.