Why do Wooden Panels like Plywood, Melamine Chipboard and MDF Warp or Bend over time?

First of all, there’s no wooden panels that do not warp or bow if they are not treated with care. So what can you do, as a designer or furniture maker, to you avoid your panels from warping? 

Warping is a deformation of the wooden panel that causes it to bend or twist out of its original shape. And here are some common reasons why wooden panels may warp:

1. Humidity Variations : Like most building materials, wooden panels are always expanding and contracting in some degree depending on their environmental conditions. Humidity changes that occur naturally through the day and night, as well as cold and raining seasons can cause moisture attack to wooden panels when improperly protected. 

2. Temperature Variations : Big changes in room temperature due to prolonged exposure to direct or indirect sunlight and UV rays can cause uneven cooling and heating of the wood, leading to warping. 

3. Improper Storage : Storing wooden panels in an environment with unstable humidity, inadequate ventilation and weak control of temperature can contribute to warping. Wooden panels should be flat laying down indoor. They shouldn’t be stored in direct contact with the ground or the walls, and they shouldn’t be unprotected from moisture attacks. 

4. Inadequate fastening or Support : Poor designs in furniture construction, such as improperly spaced fasteners during installation, designs in which long and big pieces of cabinet doors are not well supported and properly sealed, can create uneven pressure on the wood, which may cause warping. 

5. Gravity : Wooden Panels such as Melamine Chipboard and MDF are prone to sagging and bending under its own weight when they are not properly supported, both when stored improperly or when used without adequate support. 

So what can you do as a designer or carpenter to avoid the warping situation? 

1. Store Your Panels with Care : Protect your wooden panels before and during fabrication, make sure they are lying flat and protected from moisture attacks from the ground, walls and weather. 

2. Use Water Resistant Hardwood Plywoods : Use more high quality plywoods such as PF/WBP grade Hardwood Plywoods or Marine Plywoods in your furniture construction. They are made with high quality hardwood cores with higher density and strength, as well as water resistant adhesive. These type of plywoods are stronger, and they can withstand harsher condition. The downside to it is that they are more expensive than options like melamine board and MDF.

3. Avoid non-uniform Decor Materials on 2 sides : When choosing decor surfaces like Laminates or Melamine for cabinet doors, for example, try to use the exact same material with the same weight for both sides of the wooden panel. Uneven weight on 2 sides, such as 1 side being polyester and the other side being laminates, for example, can create uneven pressure during its expansion and contraction, which makes the wooden panel more prone to warping. 

4. Use Proper Support and protection in Your Furniture Design : A well thought out furniture design with properly sealed finished panels, well spaced fasteners and hinges, as well as adequate support considering the physical properties and performance of each type of wooden panels under your application, can go a long way to save you from the warping trouble. Proper joinery do wonders. It helps to explore different hardwares and accessories, metal and timber support. 

An example of clever utilisation of straightener hardware to prevent long cabinet doors and side standing panels from warping :