---
title: "What is a Plywood made of?"
description: "Thin wood veneers glued in alternating grain directions — the cross-lamination is the entire idea. Every component, the material it uses, and the constraint that mad"
url: https://atoneplace.net/made-of/plywood/
site: "At One Place"
---

# What is a Plywood made of?

**What is a Plywood made of?: Thin wood veneers glued in alternating grain directions — the cross-lamination is the entire idea.**

Marine plywood is not waterproof plywood in the sense most people assume. It is defined by a fully waterproof phenolic glue plus veneers with almost no internal voids, so a screw or an edge does not meet a hollow — but the wood itself is not treated and will rot if left wet and unfinished. Formaldehyde emissions from the resin are regulated: the California CARB Phase 2 limits became US federal law under TSCA Title VI, and European panels carry E1 or lower classifications. If a panel smells strongly of glue in an enclosed room, that smell is the resin off-gassing.

## Component by component

*Every material is a choice, and the third column is the constraint that drove it.*

| Part | Material | Why that material |
| --- | --- | --- |
| veneers | thin sheets peeled from a rotating log against a knife | Peeling gives a continuous ribbon of veneer from a whole log, which is far more efficient than sawing boards. |
| lay-up | an odd number of plies, each at 90° to its neighbours | Wood is many times stronger along the grain than across it; crossing the plies gives a panel that is strong both ways and barely moves with humidity. |
| interior adhesive | urea-formaldehyde resin | It is cheap and fast-curing, but it hydrolyses when damp, which is why interior plywood delaminates outdoors. |
| exterior adhesive | phenol-formaldehyde resin, often visible as a dark glue line | Phenolic bonds are effectively waterproof and are what separate exterior and marine grades from the rest. |
| face grade | graded faces from clear hardwood to knotty and patched softwood | The grade describes appearance and patching, not strength; a structural sheathing panel can have an ugly face and a fine glue bond. |

## Other building materials objects

- [Glass](https://atoneplace.net/made-of/glass/) — Sand melted with soda ash and limestone — three cheap minerals, floated flat on molten tin.
- [Concrete](https://atoneplace.net/made-of/concrete/) — Stone and sand glued by cement paste — and it hardens by a chemical reaction with water, not by drying.
- [MDF](https://atoneplace.net/made-of/mdf/) — Wood pulled apart into individual fibres, mixed with resin and wax, and pressed hot into a board.
- [Road asphalt](https://atoneplace.net/made-of/asphalt/) — About 95% crushed stone and sand, glued together by roughly 5% bitumen from the bottom of an oil refinery.
- [Brick](https://atoneplace.net/made-of/brick/) — Clay and shale moulded and fired until the particles partly fuse — a manufactured rock.
- [Mirror](https://atoneplace.net/made-of/mirror/) — A sheet of ordinary glass with a microscopically thin silver layer on the back, sealed under paint.

## Common questions

### What is a Plywood made of?

Thin wood veneers glued in alternating grain directions — the cross-lamination is the entire idea.

### What is the veneers of a Plywood made of?

Thin sheets peeled from a rotating log against a knife. Peeling gives a continuous ribbon of veneer from a whole log, which is far more efficient than sawing boards.

### What is the lay-up of a Plywood made of?

An odd number of plies, each at 90° to its neighbours. Wood is many times stronger along the grain than across it; crossing the plies gives a panel that is strong both ways and barely moves with humidity.

## Related pages

- [Glass](https://atoneplace.net/made-of/glass/)
- [Concrete](https://atoneplace.net/made-of/concrete/)
- [MDF](https://atoneplace.net/made-of/mdf/)
- [Road asphalt](https://atoneplace.net/made-of/asphalt/)
- [Brick](https://atoneplace.net/made-of/brick/)
- [Mirror](https://atoneplace.net/made-of/mirror/)
- [Pencil](https://atoneplace.net/made-of/pencil/)
- [Tennis ball](https://atoneplace.net/made-of/tennis-ball/)
- [Banknote](https://atoneplace.net/made-of/banknote/)
- [Golf ball](https://atoneplace.net/made-of/golf-ball/)
- [Paper](https://atoneplace.net/made-of/paper/)
- [Soccer ball](https://atoneplace.net/made-of/soccer-ball/)

## Sources

- Typical range compiled from manufacturer specifications — At One Place (/about/)