# Why Is Pizza Soggy Underneath? And a Guide to Baking Trays

> The type of tray changes the result because it determines **how quickly heat is transferred to the base**. A **dark metal** tray absorbs more heat, so the bottom browns faster, while **glass** heats slowly but holds on to its heat — so lower the oven by **15°C** when you use it.

**4 min read**

The same recipe baked in two different trays gives two different results. And that’s no accident — every material transfers heat differently, and the difference at the base can be as much as 20°C.

## Three ways heat is transferred

In the oven, heat reaches the food in three ways:

  - **Radiation** — straight from the heating elements.
  - **Convection** — from hot air moving around the oven.
  - **Conduction** — from the tray to the food, through direct contact.

**The tray controls the third** — and that is precisely what governs the base of your bake.

## Dark metal

**It absorbs radiation** more than light metal does, so it heats up faster and delivers more heat to the base.

**The result:** a base that browns faster — good for pizza and bread, risky for cakes and cookies.

**The rule:** **lower the oven by 10°C** from what the recipe says, or shorten the time.

## Light, shiny metal

**It reflects radiation**, so it heats up more slowly and delivers less heat.

**The result:** gentler cooking and softer browning — ideal for cakes, cookies and meringues.

**Light aluminium** is the default choice in most bakeries for exactly this reason.

## Glass and Pyrex

**It heats slowly** but **holds its heat for a long time** — which means the food carries on cooking after it comes out of the oven.

**The result:** a base that browns more than you’d expect as time goes on.

**The rule:** **lower the oven by 15°C**.

**An important warning:** glass breaks under **thermal shock** — don’t put cold glass into a hot oven, and don’t put hot glass on a cold surface or under the tap.

## Ceramic and clay

The slowest of all to heat up, and the best at holding on to heat.

**Ideal for long cooking** — tagines and oven dishes that cook for an hour or more.

**But they aren’t suitable** for quick bakes that need a sudden blast of heat.

**Porous clay** absorbs moisture and gives it back to the food — which is why clay-pot tagines come out moister.

## Pizza stones and baking steels

These are for when you need **very high heat at the base**.

**Pizza stone:** it also draws moisture out of the base — so you get a crisper result.

**Baking steel:** it transfers heat far **faster than stone** — it gives better results, but it’s more expensive and heavier.

**The catch with both:** they need preheating for **45 minutes** at the highest temperature — not 10 minutes.

**A free alternative:** a metal tray turned **upside down** and heated up with the oven.

## Perforated trays

Trays with holes in them let hot air reach the base.

**The result:** a crisper base, because the moisture escapes.

**Suitable for:** pizza, bread and crisp pastries.

**Not suitable for:** anything runny or soft.

## The wire rack

It isn’t a tray, but it’s an important tool:

  - **Chicken and meat** — it lets the air circulate on every side, and the juices drip down instead of stewing the underside.
  - **Crispy wings** — impossible without one.
  - **Cooling bakes** — it stops steam condensing underneath, so the base doesn’t turn soggy.

## Tray size matters

Using a different size from the one in the recipe changes everything:

  - **Bigger than specified:** the mixture is spread thinner, so it cooks faster and dries out.
  - **Smaller than specified:** the mixture is deeper, so it needs longer and the edges burn before the middle is done.

**The rule:** the mixture should fill **two-thirds** of the tray’s depth.

**And if you change the size:** adjust the time, not the temperature.

## Common mistakes

  - **Foil on the oven floor** — it reflects heat, burns the bottom and interferes with the temperature sensor. Manufacturers warn against it.
  - **Trays pushed against the sides of the oven** — they stop the air circulating. Leave **5 cm** around the tray.
  - **Two trays directly above one another** — the lower one blocks the heat from the upper one.
  - **A black tin for a cake recipe** — the base burns.
  - **Not preheating the stone for long enough** — 10 minutes isn’t enough; it needs 45.

## Baking paper vs greasing

**Baking paper** stops sticking and doesn’t change heat transfer much — the cleanest and most reliable option.

**Greasing with oil** speeds up browning on the base — good for bread, and it makes cookies spread more.

**A silicone mat** insulates a little, so the base browns less — ideal for meringues and macarons.

## Looking after your trays

  - **Metal trays** darken over time — and that changes how they behave (they absorb more heat). Bear this in mind with old trays.
  - **Don’t use wire wool** on non-stick trays.
  - **A pizza stone** shouldn’t be washed with soap — just wipe it down; the pores soak up the soap.
  - **Cast iron** should be dried over the heat and rubbed with oil.

## The shelf: half the equation

The tray controls the base, and **the shelf controls how the heat is distributed** — together, the two determine the result.

**The bottom shelf** is closest to the lower element, so the base gets more heat — for pizza, pies and bread.

**The middle shelf** is the furthest point from both elements, so the heat is more even — it’s the default for cakes, cookies and oven dishes.

**The top shelf** is for browning and finishing only — anything left there for long will burn on top.

**Turning the tray halfway through** compensates for an uneven oven — which matters especially in gas ovens, where the temperature difference between the bottom and the top is large.

## Summary

Dark metal browns the base faster (lower the oven by 10°C), light metal is gentler for cakes, glass holds its heat (lower it by 15°C), and a stone is for pizza, provided you preheat it for 45 minutes. And leave 5 cm around every tray.

## FAQ

### Why does the base burn in a particular tray?
It’s usually a dark metal tray — it absorbs more radiation than a light one, so it delivers more heat to the base. Lower the oven by 10°C from what the recipe says, or use a light-coloured tray for cakes and cookies.

### Should I lower the temperature with a glass dish?
Yes, by 15°C. Glass heats slowly but holds its heat for a long time, so the food carries on cooking after it comes out. And don’t put cold glass into a hot oven — it breaks from thermal shock.

### Is a pizza stone worth it?
Yes, if you make pizza or bread regularly — it draws moisture out of the base and gives a crunch that isn’t possible with a tray. But it has to be preheated for 45 minutes at the highest temperature, not 10 minutes.

### Should I put foil on the bottom of the oven?
No. It reflects heat and burns the bases of your bakes, it interferes with the temperature sensor in some ovens, and manufacturers explicitly warn against it. Put a tray on the shelf below instead.

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Source: https://hanakoleah.com/en/article/why-is-pizza-soggy-underneath
Edited by: Marwa Mohamed
Last updated: 2026-10-23