What Are the Mix Ratios for Marine Pour Foam and How Does Expanding Foam Work?

What Are the Mix Ratios for Marine Pour Foam and How Does Expanding Foam Work?

Marine pour foam, also known as expanding foam, is a two-part closed-cell polyurethane foam designed for flotation, insulation, and cavity filling. When the two liquid components (Part A and Part B) are mixed, they undergo an exothermic chemical reaction that rapidly expands and cures into a rigid foam.

Mix Ratios

• Ratio: 1:1 by volume (equal parts Part A and Part B).
• Measure using calibrated containers for accuracy.
• Mix quickly (20–30 seconds) and pour immediately — expansion starts fast.

How Expanding Foam Works

• The two liquid components react to create millions of tiny closed cells filled with gas.
• These cells trap air, making the foam lightweight and buoyant while also providing insulation.
• Closed-cell structure resists water absorption, making it ideal for marine applications.

Densities Available at Fiberglass Florida

• 2 lb Foam: Expands to ~9 cubic feet per mixed gallon set — ideal for flotation and general filling.
• 4 lb Foam: Expands to ~4.5 cubic feet per mixed gallon set — stronger and more impact-resistant for structural use.

At Fiberglass Florida, we carry only 2 lb and 4 lb pour foams for marine, automotive, and construction applications. Shop pour foam here.