A rib is a flat shaped tool held against the clay, and the material it is made from decides what it does. Wood compresses and shapes, metal cuts and refines, rubber smooths. Bats and a fettling knife complete the small set that most thrown work actually needs.
Wood, metal and rubber ribs
A wooden rib presses a wall from the inside or shapes a curve from the outside without removing material, and compressing a surface this way makes it stronger and less likely to crack. A metal rib cuts, refining a profile and taking off throwing rings. A rubber rib smooths and blends. Most potters own one of each before they own a second of any.
Bats and why they save pots
A bat is a removable disc that pins or sticks to the wheel head, so a thrown pot can be lifted away without touching it. Anything wide, thin walled or awkward is far more likely to survive with one, because cutting a wide pot off the head and lifting it by hand is where wide pots die. Check what bat system a wheel takes before buying either.
The pottery knife
A fettling knife is a thin, flexible blade for trimming a rim level, cutting a foot, cleaning a seam and slicing a pot in half to check wall thickness. That last use is the most valuable habit a beginner can adopt: cut one pot a week in half and the guessing about thickness stops.
Buying a few good ones
Ribs are inexpensive and the difference between a well-shaped one and a poorly stamped one is real, because a rib is nothing but its curve. Buy singly rather than in sets, choose curves that match the forms you make, and expect to acquire more over years as the forms change.
Questions people ask about pottery ribs
What is a pottery rib for?
Shaping and compressing a wall. Wood presses and shapes, metal cuts and refines a profile, rubber smooths.
Do I need bats?
For anything wide or thin walled, yes. They let a pot be lifted from the wheel without being touched.
What is a fettling knife?
A thin flexible blade for levelling rims, cleaning seams and cutting a pot in half to check wall thickness.