Clay Compatibility Guide

This chart organizes the most common bodies from Standard Clay, Montesa, and SIO-2 into compatibility groups, so you can quickly see which ones can share a build. Use the tabs to switch between brands.

A few things to keep in mind: Standard Clay and SIO-2 publish shrinkage data, so their groups are based on exact percentages. Montesa doesn't publish shrinkage, so their groups are organized by firing temperature instead, same logic, different data.

This is a living document. If you work with a brand that's not listed here, leave a comment or send me a message and I'll add it.

Clay body compatibility guide

Standard Clay · Montesa · SIO-2 — which bodies can share a build.

Standard Clay Montesa SIO-2

Mid-fire range (cone 4–6). Grouped by total shrinkage — the most precise compatibility indicator. Combine freely within a group; never cross more than one group boundary in a single build.

Grouped by shrinkage %

10% Sculpture bodies — lowest shrinkage ✓ combine freely

420Sculpture

547Red Sculpture

798Black Sculpture

10.5–11% Closest match to SIO-2 black sculpture range ✓ combine freely

553Buff Stoneware · 10.5%

112Brown · 11%

182Angel White · 11%

182GAngel White w/Grog · 11%

266G bridges B ↔ D — pick one side per build

11.5% Bridges groups above and below — not both at once ⚠ bridge only

266GUmbria w/Grog

12–12.5% Largest group — widest color range ✓ combine freely

201Gray Stoneware · 12%

213Porcelain · 12%

214Scott's Red · 12%

200Brown · 12.5%

211Hazelnut Brown · 12.5%

225Brown · 12.5%

240GWhite w/Grog · 12.5%

308Brooklyn Red · 12.5%

800Burk Speckle · 12.5%

13% White and dark contrast options ✓ combine freely

240White

266Umbria (dark brown)

365Grolleg Porcelain

551V.P. Porcelain

13.5% Pair together or with 13% only ⚠ limited pairing

563Clayer White

760Speckled

14% Highest shrinkage — isolated ✗ do not cross-group

630White Stoneware

The bridge rule: Any two bodies in the same piece must be within 1% of each other. 266G (11.5%) can join the 11% group or the 12.5% group — but not both in the same build. 266 Umbria without grog has bloating risk above cone 5 — prefer 266G for joins.

Montesa does not publish shrinkage data. Grouped by firing temperature — the only available compatibility indicator. Bodies in the same temperature group fire together safely; always test structural joins.

Grouped by firing temp

Montesa does not publish contracción (shrinkage) specs. If joining bodies structurally, request the ficha técnica directly from Montesa before production.

950–1060°C · cone 010–01 Low-fire earthenware & terracotta ✓ combine freely

TR10 Terracotared plastic body

LT 11white earthenware

Pasta M5white, low temp

Pasta M5CH 0-0.5M5 + grog

1080–1100°C · cone 03–1 SG60 family — shared base, all combinable ✓ combine freely

White base

SG60 Pasta Blancawhite · abs 2%

Colored variants — same base formula

SG60 Negro

SG60 Rojo

SG60 Ocre

SG60 Maquillaje

SG60 Amarillo

SG60 Azul

SG60 Lila

SG60 Verde Claro

SG60 Verde Esmeralda

SG60 Verde Oscuro

~1150–1220°C · cone 1–5 Medium-temp stoneware ⚠ test before joining

Gres LC79medium-temp stoneware

1260–1280°C · cone 9–11 High-temp chamotted stoneware — GBM family ✓ combine freely

White / cream — different grog sizes, same temperature

Gres Fuegocream · grog 0–1mm · ovenware

GBM CH 0-0.2fine grog

GBM CH 0-0.5medium grog

GBM CH Impalpablevery fine grog

GM CH 0-0.5chamotta 0–0.5mm

GTB 75

Colored — same family, same temperature

GC 0-0.5 Griscement gray

GMN Negro 0-0.2black

GMR Rojo 0-0.2red

RM 50red firing body

1280°C · cone 10–11 Porcelain & casting bodies ⚠ casting — not for structural joins

Gres G21white casting stoneware

Porcelana P 26very white · casting

Porcelana P 83porcelain

Never cross temperature groups. A body fired at 1080°C joined to one needing 1260°C will be under-fired, cracked, or both. The SG60 colored range is safe to mix because all share the same base formula and firing temperature.

Spanish brand (Cerámica Collet, Valencia). Publishes both drying and firing shrinkage. All high-fire bodies fire cone 5–10 (1200–1300°C) with 40% grog at varying granulometries. Grouped by total shrinkage (drying + firing).

Grouped by shrinkage %

Low fire · cone 06–05 · ~1000°C Earthenware bodies — separate firing range same temp only

PAWhite Earthenware

PFRed Earthenware

PMBlack Earthenware (manganese)

Low-fire earthenwares (cone 06–05) cannot be combined with high-fire bodies (cone 6–10). They fire at completely different temperatures.

~10% total · cone 6–10 Lowest shrinkage — sculpture & raku bodies ✓ combine freely

PRAFWhite Sculpture / Raku · 35 mesh · 5.4+4.6%

PRNF & PRNI bridge ~10% ↔ ~13% — pick one side per build

~11.5–12% total · cone 5–10 Mid shrinkage — black sculpture range ⚠ bridge only

PRNFBlack Sculpture · 35 mesh · 8.1+3.7% · best cone 5–7

PRNIBlack Stoneware · very fine grog · cone 6–10

~12–13% total · cone 6–10 Main high-fire range — widest color selection ✓ combine freely

White / ivory bodies

PRAIWhite Stoneware · 80 mesh · 5.9+7.0%

LunaSpeckled Stoneware · ivory w/ dark specks

Gray / neutral bodies

ZumaiaGrey Sculpture · 35 mesh

Berlin GreyGrey Stoneware · fine grog

Red / warm bodies

MarteRed Sculpture · 35 mesh

ToffeeWarm speckled stoneware

Porcelain & specialty · cone 6–10 Shrinkage not published — test before joining ⚠ test required

AnetoWhite Porcelain · translucent

UpsalaBlue Porcelain · cone 6–7

LagoonTurquoise Porcelain

CellulainPaper Porcelain · translucent

PCLIStoneware Paper Clay

Key rule for SIO-2: PRAF (10%) and PRAI (12–13%) are both white and look interchangeable — but they have a 2–3% shrinkage gap and should not be joined in the same piece. PRNF Black (11.5–12%) can bridge to PRAF but not to PRAI without stress. Always match your white to the shrinkage group of your dark body.

Grog size reference (SIO-2) Impalpable = 0–0.2mm (80 mesh) — smoothest surface Fine = 0–0.5mm (35 mesh) — slight texture Coarse = 1–3mm — rich textured surface

Data sourced from standardclay.com, montesapc.com, and sio-2.com. Shrinkage values are manufacturer-published averages — actual results vary by kiln, firing speed, and cone. Always test new body combinations before production.