Mudtools Stainless Steel Rib Size 5 Firm - Large Kidney Shape - Ceramics, Pottery, Clay - SS5 Review (2026)

Who the SS5 is built for

Mudtools describes the Shape 5 stainless rib as the same traditional kidney shape as its smaller Shape 0 and Shape 1 ribs, only bigger, which puts it squarely in the toolkit of potters who regularly throw larger forms such as big bowls, platters or wide vases where a small rib takes too many passes to cover the surface. The added surface area is specifically called out by Mudtools as useful for smoothing a slab of clay as well as making broad, even passes on larger thrown forms, so hand builders working with slabs benefit from the size as much as wheel throwers do. Potters who mainly throw small cups and mugs will likely find the SS5 oversized for that scale of work and better served by a smaller rib from the same Shape 0 or Shape 1 line.

Material and construction

According to Mudtools, the rib is cut from cutlery grade stainless steel, a material choice that gives it both rigidity and resistance to rust from constant contact with wet clay and slip, which is a real advantage over tools that can corrode with heavy studio use over years. One retailer lists the tool at roughly 2 by 4.13 inches, and Mudtools describes its response as extra-flex for fine shaping and finishing despite being metal, which suggests the steel has some give rather than being perfectly rigid like a straight-edged scraper. The kidney shape carries over from the smaller ribs in the same product family, giving the tool both a curved edge for following bowl interiors and straighter sections for flatter passes across a slab or plate bottom.

Using a firm metal rib without gouging clay

A firm stainless steel edge like this one is effective at quickly scraping away excess slip and refining the profile of a form, which is faster than working the same area with a soft polymer or silicone rib, but that same firmness means it can dig into soft or overly wet clay if a potter applies too much pressure or attacks the surface at too steep an angle. Most potters reach for a firm metal rib like the SS5 once a form has firmed up somewhat on the wheel or during the leather hard stage of hand building, rather than on freshly thrown, still-soft walls where a gentler polymer rib is the safer choice. Learning the right pressure and angle for a given clay's moisture level is really the main skill involved in getting good results from any firm metal rib, not something specific to this tool alone.

How it compares with other ribs

Against Mudtools' own Shape 1 yellow soft polymer rib, the SS5 is a firmer, larger tool meant for a different stage of work, scraping and refining rather than gentle finishing on soft clay, so the two are complementary rather than competing purchases for most potters. Compared with silicone ribs from Xiem Tools or Sherr, the SS5's stainless steel construction removes any concern about the rib wearing down or tearing the way a soft silicone edge eventually can, at the tradeoff of being less forgiving on delicate, wet surfaces. Diyoohomy and Impresa's soft silicone rib kits are priced for buying several ribs at once, while the SS5 represents a single, more specialized purchase aimed at potters who already know they need a large firm scraper in their kit.

Bottom line

The Mudtools SS5 earns our score of 8.8 out of 10 as a durable, purpose-built stainless steel rib that fills a real gap for potters working on larger thrown or hand built forms. Its size and firmness make it most useful once a piece has firmed up enough to handle a metal edge, and beginners should pair it with a softer rib for earlier stages of a piece rather than relying on the SS5 alone. Potters who mainly work small, or who are just starting out and want one forgiving all-purpose rib, will likely get more immediate use from a softer polymer rib first and can add the SS5 once they are regularly throwing bigger work.

Frequently asked questions