Biscotto Stones for Pizza Ovens: Clay vs. Cordierite, and What Your Oven's Maker Allows

What a biscotto clay stone changes compared with the cordierite stone in an Ooni or Gozney oven, the trade-offs, and what the makers' manuals and warranties say before you swap one in.

By Jay Arr Published Updated

Biscotto stones have a strong following among owners of portable pizza ovens, usually as a fix for bases that scorch before the top is done. This page covers what the material is, what the physics does and doesn’t support, and what the oven makers say about swapping their stone for one.

What a biscotto stone is

Biscotto, often sold as biscotto di Sorrento, is a slab of fired clay. Makers such as Saputo describe their stones as handmade from Naples-area clay and kiln-fired; that’s a description of their own product, not of everything sold as biscotto. In portable ovens it’s sold in sizes cut to replace a particular model’s stock stone, which is usually cordierite, a ceramic.

One popular claim needs correcting. Biscotto is often described as the floor material that certified Neapolitan pizzerias must use. The Associazione Verace Pizza Napoletana’s 2022 rules don’t name a floor material. They describe the traditional oven’s floor as preferably laid in four pieces on a bed of sand and salt, and give a floor temperature of about 380 to 430°C.

What the physics supports

How fast a floor pushes heat into dough depends largely on its thermal conductivity. Modernist Pizza explains the trade-off for oven floors made of stone or refractory materials: low conductivity with a high heat capacity lets the floor store plenty of heat and bring the base of the pizza up to boiling almost at once, but then it restrains how fast heat keeps pouring in once the crust starts to form. Metal floors sit at the other extreme. The book puts aluminum’s conductivity at roughly 100 times a firebrick or refractory-cement hearth’s, and stainless steel’s at about 30 times, and warns that such floors conduct heat so fast they risk overbaking the bottom.

Sellers say biscotto conducts heat more slowly than cordierite and so browns the base more gently. We couldn’t find an independent measurement of either material in these ovens, and general heat-transfer physics can’t tell you how a particular, unmeasured stone will behave, so we’ve dropped the conductivity figures this page used to quote.

Low conductivity has a cost, too. Modernist Pizza notes that after a pizza comes out, heat from deeper in a stone floor moves up only slowly, because the material isn’t a good conductor; the floor recovers mainly by absorbing radiation from the hot ceiling. Whatever the floor is made of, measure it rather than assuming it’s ready.

What the oven makers say

This is the deciding question, and it’s the one sellers rarely mention. As published by each maker, checked October 14, 2026:

OvenStock stoneWhat the maker says
Ooni Koda 1615 mmManual: don’t modify the appliance; don’t repair or replace any part unless the manual specifically recommends it
Ooni Koda 2 / Koda 2 Pro15 mm / 20 mm cordieriteCheck the exact model’s manual; a rotating-stone accessory has its own instructions
Ooni Karu 2 Pro15 mm, supplied as two stonesCheck the manual before changing the floor
Gozney RoccboxFixed in place (our oven guide); thickness not verifiedManual: don’t modify the appliance or manipulate parts sealed by the maker. Our oven guide’s profile: don’t pry out the fixed stone
Gozney Arc / Arc XL20 mm, removable (Gozney)Manual: don’t modify the appliance

Ooni’s warranty terms also say that if you have altered a product in any manner, the warranty is void, and that coverage depends on using the oven according to its manual. If your stone breaks, Ooni’s warranty page says to get in touch for help.

We found no biscotto replacement sold by Ooni or Gozney for the models covered here when checked on October 14, 2026. Don’t fit an unapproved replacement. Ask the maker to confirm that exact stone and installation for your model; permission to replace a damaged original floor isn’t permission for any stone sold in the same size.

Trade-offs if you do get approval

If your oven’s maker confirms a biscotto for your exact model and how to install it:

  • Thickness and fit. Compare the slab’s thickness with the stock stone. A thicker floor shrinks the opening and the space above the pizza. The Arc XL’s opening, for example, is only 3.7 inches (9.5 cm) tall.
  • Browning. Sellers claim gentler browning than cordierite, but there’s no independent measurement to set your expectations by, so judge from your floor readings and the bake itself.
  • Recovery. Check the floor before each pizza. For a Neapolitan-style pizza, the oven guide’s range is 750 to 850°F (400 to 450°C) on the floor, measured at three spots.
  • Handling. As with any stone, install and remove it cold, and never cool a hot stone with water; Gozney warns that water will likely crack one.

Biscotto or steel in a portable oven?

A steel goes the other way. Modernist Pizza puts a baking steel’s thermal conductivity at more than five times a baking stone’s, and metal floors carry the overbaking risk described above. In a portable oven at full heat, that’s the opposite of what most biscotto buyers want. It’s also the same kind of swap, so the same manual and warranty questions apply.

In a home oven the logic reverses. A kitchen oven tops out around 500 to 550°F, and Modernist Pizza strongly recommends a baking steel there to crisp the base. For a home oven, a steel is the better fit; see the baking steel thickness guide.

Fixing a scorched base without changing the stone

Most of the problems a biscotto is bought to solve have approved fixes:

  1. Measure the floor at three spots before each pizza, and launch only when all three are in range. If the floor reads above the range, let it settle rather than launching.
  2. Launch into the middle of the stone, away from the burner, as Ooni’s Koda 16 guide says.
  3. Turn often. Ooni’s guide gives every 20 to 30 seconds for a Neapolitan-style pizza in the Koda 16.
  4. Lower the heat with the oven’s own controls if the floor reads above the range, and give it time to settle. New York-style pizza needs lower heat: 700 to 750°F (375 to 400°C) on the floor.

More on heat distribution in pizza oven flame guards and heat diffusers, and on why floor color matters in oven floor emissivity.

Frequently Asked Questions

What is a biscotto stone made of?
Fired clay. Makers such as Saputo describe their biscotto, often called biscotto di Sorrento, as handmade from Naples-area clay, and sellers cut it to replace the stock stone in specific pizza ovens. The Neapolitan pizza association's 2022 rules don't require it; they describe a traditional floor laid in four pieces on a bed of sand and salt.
Will a biscotto stone fit my Ooni Koda 16?
Sellers cut them to the Koda 16's size, but fit isn't the only question. Ooni's Koda 16 manual says not to replace any part unless the manual specifically recommends it, and Ooni's warranty is void if the product is altered in any manner. Ask Ooni before you swap the stone.
Does a biscotto stone bake a softer base?
Sellers say it browns the base more gently than cordierite. Modernist Pizza explains how low-conductivity floors in general restrain browning once the crust starts to form, but that doesn't measure any particular stone, and we found no independent comparison in portable ovens. Treat sellers' claims as claims, and measure the floor before launching.
How long should I preheat a biscotto stone?
Follow your oven's manual, then measure rather than timing it. The oven guide plans 25 to 40 minutes for outdoor ovens and treats the oven as ready when three infrared readings across the floor are in range, 750 to 850°F for a Neapolitan-style pizza.
Can I use a biscotto stone in my home oven?
It isn't the right choice there. Home ovens top out around 500 to 550°F, and Modernist Pizza strongly recommends a baking steel in a home oven to crisp the base.

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