---
product_id: 273973809
title: "4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit)"
brand: "fiberglass supply depot"
price: "€ 129.20"
currency: EUR
in_stock: true
reviews_count: 8
category: "Fiberglass Supply Depot"
url: https://www.desertcart.ie/products/273973809-4-lb-density-expanding-pour-foam-2-part-polyurethane-closed
store_origin: IE
region: Ireland
---

# 2 cubic feet coverage per kit 5 min full expansion time 4 lb density for superior flotation 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit)

**Brand:** fiberglass supply depot
**Price:** € 129.20
**Availability:** ✅ In Stock

## Summary

> 🛠️ Expand Your Potential with Foam That Works as Hard as You Do!

## Quick Answers

- **What is this?** 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit) by fiberglass supply depot
- **How much does it cost?** € 129.20 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.ie](https://www.desertcart.ie/products/273973809-4-lb-density-expanding-pour-foam-2-part-polyurethane-closed)

## Best For

- fiberglass supply depot enthusiasts

## Why This Product

- Trusted fiberglass supply depot brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Rapid Expansion:** Expands fully in just 5 minutes, letting you work fast and stay ahead of the project curve.
- • **Precision Mixing:** Two-part polyurethane system with a 45-second working window for exact control and flawless results.
- • **Multi-Use Mastery:** Perfect for soundproofing, insulation, sculpting, filling voids, and even taxidermy—one kit, endless possibilities.
- • **Buoyant Powerhouse:** 4 lb density closed-cell foam ensures unmatched flotation and durability for marine and dock applications.
- • **Versatile Compatibility:** Seamlessly laminates with polyester, epoxy, or vinyl ester resins without melting or damage.

## Overview

Fiberglass Supply Depot’s 4 lb density expanding pour foam is a high-performance, two-part polyurethane closed-cell liquid foam designed for boat and dock flotation, soundproofing, insulation, and filling voids. This 1-gallon kit yields 2 cubic feet of foam that cures quickly and bonds with common resins, making it ideal for professional-grade marine, industrial, and creative applications.

## Description

Product description

Review: Good product. - Works well. Be quick and ready for it, it expands quickly and will come for you if you're not prepared to control it.
Review: Works great - Works great , quick set up and easy to use

## Features

- Flotation Foam is a polyurethane 2-part foam that, when mixed in equal parts and poured in place this foam will soundproof, insulate, or provide extra buoyancy.
- 4LB. Density polyurethane flotation Foam 1 Gallon Kit; Consists of 1/2 gallon of Part A and 1/2 gallon of Part B and produces 2 cubic feet.
- Once fully cured this foam can be laminated over with any type of polyester, epoxy or vinyl ester resin without melting.
- The 4LB density also works well in floating decoy or taxidermy applications as well as many other sculpting, casting, carving and other filling applications
- All expansion rates and times given are temperature critical. Temperatures below 75° F will lower the expansion rate therefore requiring more foam. Ideal working temperature is 75° to 80° F or above. Accurate measuring of these products is extremely critical. Working time before foaming: approx. 45 seconds Time before full expansion: approx. 5 minutes

## Technical Specifications

| Specification | Value |
|---------------|-------|
| Brand | Fiberglass Supply Depot |
| Manufacturer | Fiberglass Supply Depot Inc. |
| Material | Foam,Resin |
| Recommended Uses For Product | Flotation, Soundproofing, Insulation, Filling Voids, Sculpting, Casting |
| UPC | 819794022934 |

## Product Details

- **Brand:** Fiberglass Supply Depot
- **Manufacturer:** Fiberglass Supply Depot Inc.
- **Material:** Foam,Resin
- **Recommended Uses For Product:** Flotation, Soundproofing, Insulation, Filling Voids, Sculpting, Casting
- **UPC:** 819794022934

## Images

![4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit) - Image 1](https://m.media-amazon.com/images/I/81ySuM57MmL.jpg)
![4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit) - Image 2](https://m.media-amazon.com/images/I/8189VtbwU2L.jpg)
![4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit) - Image 3](https://m.media-amazon.com/images/I/71Gbm9XW+IL.jpg)
![4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit) - Image 4](https://m.media-amazon.com/images/I/71Jn4WV0S0L.jpg)
![4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit) - Image 5](https://m.media-amazon.com/images/I/81mbAHsaZfL.jpg)

## Questions & Answers

**Q: What is the compressive strength of the foam, in  PCF?**
A: They only give the compressive strength in PSI and that is 78 for the 4lb foam

**Q: What is the viscosity of the liquids before they mix?**
A: The best way to describe it would be like warm pancake syrup.

**Q: i'm new at this..what does density mean i see 2lb..4lb..6lb? thanks**
A: Think of it as hardness or strength. The 2lb will be more sponge like 6 will be harder.

**Q: Can you use pole foam to insulate the walls of a shop? Does it go thru a heat?  Will it blister the tyvek or metal on the outside?**
A: It doesn't fill a very big volume like spray foam. It is very liquid and comes out of any cracks. Will set up hard as a rock though.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Good product.
*by R***H on March 8, 2025*

Works well. Be quick and ready for it, it expands quickly and will come for you if you're not prepared to control it.

### ⭐⭐⭐⭐⭐ Works great
*by J***D on May 28, 2025*

Works great , quick set up and easy to use

### ⭐⭐⭐⭐⭐ Pool step repair.
*by 1***Y on December 20, 2025*

Being a more dense foam I was hoping for more expansion but it did the job. I used this to repair my pool steps from where improper install caused the dirt to wash out underneath them. This filled the void well.

## Frequently Bought Together

- 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit)
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- 6 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boats, Dock Flotation, Carving, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit)

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*Product available on Desertcart Ireland*
*Store origin: IE*
*Last updated: 2026-02-26*