Even though our fingers serve as our primary throwing tools, there are times when a throwing rib does a better job. Ribs are a potter’s best friend when it comes to defining profiles, wringing out water or adding decorative touches. In the beginning, actual animal ribs were used for this purpose—and hence the name—but now contemporary ribs are commonly made from wood, metal,and plastic.
There are many functions that ribs perform, which is one of the reasons they’re so important. The most common uses for ribs are for manipulating profiles and removing throwing marks while compressing the clay and removing excess water. When throwing porcelain, it’s often best to use a rib on one side of a pot and a sponge on the other, or even to throw with two ribs. The rib provides support, especially when making large voluminous forms.
Because of the variety of shapes available, you can find a rib to suit any profile you wish to make. Using a rib for the inside profile of a bowl can assure a continuous line from the bottom through to the rim. And using the same profile repeatedly helps in making multiples for sets. Specialized ribs with notched profiles can also be used on the exteriors of pots to add a decorative touch or even shape and refine the foot and rim.
When throwing large forms, too much water in the clay is a problem once you have the preliminary shape completed. How many times have you tried to get that final shape only to have the form collapse? To prevent this, remove all the slurry water using a sharp-edged metal rib to ‘wring’ the excess water out. This increases your chances of success and prevents distorting or collapsing the form. It also provides a way to get sweeping curves on bowls and platters.
This article appeared in Pottery Making Illustrated magazine’s May/June 2010 issue. To get great content like this delivered right to your door, subscribe today!
Getting the most out of using a rib is simple. While you can generally get by without using a rib for small bowls, medium to larger bowls really benefit from this tool. The best way to use the rib is to have the wheel rotating at medium to low speed (the bigger the piece, the lower the speed),work the rib up from the bottom of the bowl, curving the clay outward a little with each pass from the bottom to the top. With your right hand, always follow the position of the rib with gentle sponge or finger pressure on the outside of the bowl, supporting the clay. Continue with successive passes until the bowl takes the shape you want.
Remember, when using a rib to shape a form, always hold it at an angle to the surface so it slides smoothly over the clay rather than scraping or cutting into it. After trimming, you can use ribs to eliminate trim tool marks, but you’ll need to be careful to hold the rib at an angle to prevent chattering and grog trails.
Metal ribs, while suitable for throwing, are commonly used in handbuilding for their ability to scrape clay and compress seams.
After the first few weeks in pottery, you’ll want to look at having more ribs on hand than what came in the basic pottery tool kit you started with. If cost is a factor, you can find reasonably priced wood, rubber,and metal ribs that can serve your needs.
As you advance, you’ll find that specialty ribs for bowl interiors (from small to large and wide to steep), for making large or flanged plates and platters, defining corners,creating decorative profiles, and those designed to remove slip or trimming tool marks will make your work easier and expand your repertoire of forms.
A mixture of rigid and flexible ribs as well an assortment of metal, wood, and plastic ribs can also accommodate most any situation in both throwing and handbuilding. Luckily, even the most expensive ribs are affordable and will last a lifetime (or until lost or borrowed).
- Bamboo Tools
Bamboo tools have been used in Asia for centuries. Durable, flexible, and lightweight, bamboo can be shaped with a sharp knife and will hold an edge that stands up to heavy use. Bamboo Tools offers a variety of curved, straight and profile ribs.
- Chinese Clay Art USA
Chinese Clay Art produces a set of five wooden ribs with different profiles and a set of three different sizes of rubber ribs. For the budget conscious or those looking to provide supplies in a classroom setting,these provide a perfect solution.
- Kemper Tools
Kemper makes eight wooden rib profiles that include the basic shapes required for opening, shaping, curving, smoothing, and trimming.Their flexible metal ribs are made for scraping, and a collection of rigid metal ribs can also be used as squeegees to remove excess water from pottery shapes.
- MKM Pottery Tools
MKM makes a variety of ribs out of wood, steel, and coconut. In both the wood and steel series, there are 22 different profiles of varying sizes, each with a specific purpose or combination of uses. Their coconut shell ribs vary in size, shape, and thickness but are durable and comfortable to hold.
Developed by Michael Sherrill, Mudtools are made from a silicone plastic material in six shapes and in four different hardnesses from very soft to very firm. The softest ribs can be used even on rims like a chamois and the firmest are nearly as firm as wood. Mudtools also produces six stainless steel ribs in an assortment of profiles.