Density and firmness are often used interchangeably in conversation - but the two are very different. Another common misconception is that higher density = more firm.
The truth is a little more complicated.
Foam Density vs Firmness
First, we need to address the main question of this blog. A higher foam density DOES NOT mean a firmer foam. Density and firmness aren’t related in that way. A high-density foam could be soft and squishy to the touch and a low-density foam might be extremely firm.
Densityis a measure of how compact a foam is. We measure density by the mass of a foam’s material within a given space. Density impacts the weight of the foam part however, density has no impact on the firmness of foam packaging across different materials.
Firmness is a measure of how much a foam compresses when weight is applied to it. This is entirely defined by the type of foam - not by the density at all. Foam firmness exists in a range, numbered by the amount of weight of pressure per square foot a type of foam can take.
Sometimes the easiest way to conceptualize the difference between the two is the move outside of packaging, into other foam applications. Think about the difference in weight, feel, and firmness between a section of Styrofoam and a foam mattress - even if they’re nearly the exact same thickness. Both are often made with low-density foam, but one is hard and brittle and the other is soft and flexible.
Foam Density and Firmness in Packaging Foam
Both density and firmness are critical considerations in packaging foam. If your product is heavy, a high density, very firm foam is required to keep it locked in place and prevent damage during shipping.
The best way to identify the ideal density and firmness for a packaging foam is dependent on the specific product being shipped. The best way to determine that is to partner with a foam packaging expert, like Foam Industries.
Foam Industries is a custom protective packaging company specializing in foam – with additional wood and plastic fabrication services. Our custom foam fabrication services are ideal for any type of packaging, display, or support service needed – from design to finished product.