Proper Use of Ribs

There’s no doubt that the proper use of ribs is essential to throwing well-surfaced and consistent pots on the potter’s wheel. However, with the wide variety of ribs out there it may at times be tricky to match a rib to your specific needs when shaping and finishing the surface of a pot, as well as to utilize a specific rib for its intended purpose. Let’s look at some of the basics of the more common ribs available, as well as introduce a few ideas for some modified and do-it-yourself ribs, all of which I have found work the most efficiently and consistently in my experience as a production potter. However, these demonstrations will certainly not cover each rib’s full potential as a useful tool for texture and design that’s limited only by the artist’s experimentation and imagination.

I will primarily focus on the steps that immediately follow the formation of a basic cylinder on the potters wheel. Ribs can be used for either straightening or curving the walls of the vessel to form the finished pot of your choice, as well as cleaning up and smoothing out finger ridges or scratchy surfaces, and to strengthen and extend the walls of a vessel beyond what’s considered comfortable. Please keep in mind that the wheel-thrown pieces in the following examples aren’t meant to be finished pots. I’m working with the simplest of forms to focus specifically on the ribs themselves, and encourage you to utilize these techniques on your own unique pieces.

Wood Rib

This is probably the most commonly used wooden rib in pottery. This specific one, made by Kemper, is found in most pottery start up kits. I likely use one every time I’m at the wheel as it’s a versatile and useful tool and a great beginner’s rib. When brand new, these ribs have a nice sharp edge, which is necessary for producing clean and straight surfaces. Over time the edge dulls, but it can be easily brought back to life with a sander. The cylinder is about 1½ pounds of white stoneware I have just finished pulling into a basic starting form.

1 Hold the rib with the pointed end down and push out from the inside of the cylinder to form a vertical, ridge-free profile.

2 After straightening the vessel, the tip of the rib can be angled and pushed into the base of the form to create an undercut.3 This rib is a kitchen countertop sample. Use it like the rib in image 1 to straighten a form and remove throwing lines.4 Hold this countertop rib flush against the wheel at a 45° angle for a clean undercut to the bottom of the vessel.

Holding the rib with the pointed end facing down, I’m pushing out from the inside of the cylinder into the long edge of the rib to give the form a vertical profile, thus removing finger ridges and cleaning excess moisture and slurry from the surface. Slowly continue this move to the top of the cylinder (1).

After straightening the vessel, the tip of the rib can be angled just so and pushed into the base of the form to give it an undercut that requires minimal clean up once it’s dried (2).

Kitchen Countertop Sample

Here’s an example of a DIY rib. This is a kitchen countertop sample—they are free and plentiful at most home or flooring sales stores. What makes this a great rib is that it’s thin and rigid. Since the edge of this makeshift rib is so thin, there’s no need to keep its edge sharpened like the common wooden rib, so it will always leave behind a nicely cleaned and straight wall.

Just like in the first example, press into the edge of the rib from the inside of the cylinder from bottom to the top (3). Held flush against the wheel at about a 45° angle, this rib will also give a clean undercut to the bottom of the vessel (4).

5 After shaping, use a soft polymer or rubber rib to smooth the surface completely if you want a very polished surface.6 Rest the base of the contour rib on the wheel head. Push the pointed tip of the rib into the foot of the vessel to narrow it.

7 Push out against the rib to shape and clean the outside of the bowl. Use the rib’s curved top to make a laid-over rim.8 This contour rib has a 90° angle at the top edge so it can create a pleasing break or ridge underneath the rim of the bowl.

Rubber Rib

There are many quality rubber or polymer ribs on the market, in different shapes and flexibility. The most common ones are the Sherrill Mudtools ribs (5). I use this rib (Mudtools Red Very Soft Polymer Rib, Shape 4) in the final step in cleaning the surface of a finished form as it is the softest of the Mudtools ribs and can be bent to fit the contour of your pot, whether straight or curved, with minimal pressure and a light touch so as not to dent the surface of the final form.

The cylinder in this example is the same piece shaped with the countertop rib in the previous example. As you can see in figure 4, though the rib did a great job in straightening out the wall, it didn’t do much for smoothing the surface completely, which is why I like to do the finishing touch with the rubber rib for a very polished surface.

Cutting-Board Ribs

Another example of a DIY rib is this custom profile rib I have made out of a plastic cutting board. This was made by tracing a form onto a cutting board, cutting it out with a jig saw, then using a Dremel tool with a sanding wheel bit to bevel and sharpen the edges, much like the edge of a basic wooden tool. Often I am tasked with making large numbers of matching bowls, so I find that a curved profile tool with a flat wide bottom that sits flush on the wheel head can help with quick shaping, surface cleaning, and consistency. Once you get the hang of using the curved profile of this tool, it can be used for a variety of different sizes of bowls.

9 Press the tip of the notched wooden rib into the base of the pot to create the foot, and omit the extra step of trimming later.10 Move the rib up and press into the edge from the inside of the bowl to shape the pot’s profile.

11 After straightening with the wooden rib, wet the surface, and push out from the inside into the metal rib’s long flat edge. 12 Refining with the metal rib compresses and reinforces the form’s walls while removing ridges and excess moisture.

Resting the wide base of the rib flush with the wheel head, I push the pointed tip of the rib into the foot of the vessel quite far. Even if the foot of the pot is naturally wide, it can be pushed into a tighter foot prior to finishing the final shaping (6). Once the width of the foot is established, I push out into the contour of the rib from the inside of the bowl from bottom to top, forming the curve of the bowl (7).

Since the top of the rib’s profile is curved, I can use that contour to roll the lip of the bowl into a nice, laid-over rim. The rib does most of the work here, simultaneously shaping and cleaning the outside of the bowl.

This white cutting-board rib has the same contour as the red one; however, the top of the profile breaks off at a near 90° angle.

After the form of the bowl has been made using the curve of the rib, the upper wall of the bowl is pushed into the top edge of the rim so it can create an aesthetically pleasing break underneath the rim of the bowl (8). If you don’t have the tools to make your own, a number of ceramic suppliers offer contour ribs.

Modified Wooden Foot Rib

This is a basic wooden rib I have modified to create an instant foot at the base of forms. Using a sander, I have straightened out and beveled the original curve of the rib’s upper profile and using a Dremel tool with a sanding bit, I have nicked out a curved “bite” in the tip of the rib, which I use to create a foot. The vessel in this example is a larger 2-pound bowl that will be shaped and footed with this rib.

Press the tip of the rib into the base of the pot to create the foot. Again, the rib can be pressed even deeper into the base, creating a narrower foot as the excess clay will be shaved off by the rib (9). Don’t be afraid to press deep into the base of your form­—the tighter the foot, the more elegant the shape.

Press into the edge of the rib from the inside of the bowl after removing the tip from the foot and continue shaping the pot’s profile (10). Finish shaping the wall and lay over the rim for a graceful footed bowl.

Stainless Steel Metal Ribs

When working with larger forms that will be pushed out from the inside to form more elegant curved vessels, you may sometimes run into the issue of finger ridges resurfacing. It’s easy to smooth out finger ridges when you’re making precise vertical forms, but once you start stretching out walls from the inside, the previously hidden finger ridges can start coming back, creating a striped pot. Working with a combination of these two Kemper Metal Scraper Ribs (see G and H, at right and figures 11–13)  in the final shaping of larger forms is a reliable method of keeping finger ridge re-exposure to a minimum. Just as importantly, using metal ribs for final shaping helps to compress and strengthen the walls, which can help prevent collapsing of the form and encourage even further stretching of the walls to its full potential. The vessel I am using them on is a 4-pound, freshly thrown cylinder that has just been straightened with the wooden rib (A).

I saturate the surface of the vessel with water and start pushing out from the inside into the flat edge of the long metal rib (11). Moving upward and back inward to form a curved profile, the process of straightening with the metal rib compresses the walls while reinforcing and strengthening them and removing excess moisture (12). If the initial process of pushing out the pot from the inside were done without a rib, then most of the original finger ridges will start to resurface, but the combination of pushing out the walls from the inside while compressing with a metal rib will smooth out the ridges and keep them from resurfacing.

13 Repeat the process from figure 12 with the small metal rib to push out the walls quite far while maintaining compression.

This smaller metal rib is lighter and has more flexibility so I use it to further round the pot’s walls. Starting in the middle of the form where you want a curve to begin, push out from the inside into the metal rib’s flat side while holding a curve in the rib (13).

Repeating this process with the small metal rib, moving up and down the vessel, allows you to push out the walls quite far—possibly further than expected—all the while keeping the surface smooth, compressed, and free of finger ridges. This action of curving the rib acts as a kind of “nook” that you’re pushing the walls into and the motion of pulling from bottom to top leaves behind a graceful, smooth, and compressed curved form.

These are the basics of the different uses of the potter’s ribs. It’s nearly impossible to cover every conceivable use of each and every rib out there so it’s important to experiment, be creative, and find what works for you. Keep your eyes open. Look at the ribs that are available and look at common items that can be used as ribs or made into custom shapes. Clay is such a forgiving medium that it’s always surprising what you can use.

Jared Zehmer is a journeyman potter who lives and works in Seagrove, North Carolina. Follow him on Instagram: @jaredzehmer.

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1 Jared Zehmer’s jar.2 Jared Zehmer’s plate.3 Jared Zehmer’s jar.