---
product_id: 282511397
title: "Fiberglass Supply Depot 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethan..."
brand: "fiberglass supply depot"
price: "$453.69"
currency: USD
in_stock: true
reviews_count: 10
category: "Fiberglass Supply Depot"
url: https://www.desertcart.us/products/282511397-fiberglass-supply-depot-4-lb-density-expanding-pour-foam-2
store_origin: US
region: United States of America
---

# 4 cubic feet coverage per 2-gallon kit 4 lb density for durable, closed-cell foam 45 sec working time, 5 min full expansion Fiberglass Supply Depot 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethan...

**Brand:** fiberglass supply depot
**Price:** $453.69
**Availability:** ✅ In Stock

## Summary

> 🚀 Expand Your Projects with Precision & Power!

## Quick Answers

- **What is this?** Fiberglass Supply Depot 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethan... by fiberglass supply depot
- **How much does it cost?** $453.69 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.us](https://www.desertcart.us/products/282511397-fiberglass-supply-depot-4-lb-density-expanding-pour-foam-2)

## 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

- • **Resin-Compatible Finish:** Fully cured foam laminates seamlessly with polyester, epoxy, or vinyl ester resins
- • **Precision Expansion Control:** Optimized for 75-80°F to maximize foam yield and minimize waste
- • **Multi-Functional Performance:** Soundproof, insulate, float, sculpt, and fill voids with one versatile foam
- • **Rapid Setup for Professionals:** Quick 45-second working window ensures efficient project flow without downtime
- • **Temperature-Smart Application:** Adjust usage based on ambient heat to avoid over-expansion and costly messes

## Overview

Fiberglass Supply Depot’s 4 lb density 2-part polyurethane expanding pour foam delivers 4 cubic feet of closed-cell foam designed for flotation, soundproofing, insulation, and filling voids. With a rapid 45-second working time and compatibility with major resin types, it’s engineered for professional-grade applications requiring durable, lightweight, and versatile foam solutions. Ideal for millennial pros who demand efficiency, precision, and multi-use performance in their craft and repair projects.

## Description

Buy Fiberglass Supply Depot 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (2 Gallon Kit): Pillow Forms & Foam - desertcart.com ✓ FREE DELIVERY possible on eligible purchases

Review: Expanding Foam - Product works as described Using on motor coach void areas
Review: Be mindful of temperature - I used this to repair some damage to a classic 13 Boston whaler. I actually redid the floor and have a word of advice for anyone new to this type of product. Prep your area well and understand the impact ambient temperature has on this foam. While liquid and while mixing/pouring this foam sticks to everything. EVERYTHING. I use masking tape and those cheap brown rolls of contractor paper to make sure the only thing exposed to the foam before and after expansion is the hole I’m pouring into. Regarding the temperature: the hotter it is outside the faster the foam mixes and needs to be poured. Also the hotter it is outside the more your foam will expand overall. I tried filling a small hole on a 70 degree day and the foam performed well. I thought….. the next week I filled a similar sized hole and used the same amount of foam. Only difference was the temperature outside was in the 90’s. I had the foam expand at least twice as far and ooze out all over the place. Just be mindful of them temp and as expensive as this foam is I suggest doing it on the hottest days you can so that you get the most expansion.

## 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 2 Gallon Kit; Consists of 1 gallon of Part A and 1 gallon of Part B and produces 4 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 |
|---------------|-------|
| ASIN | B08V5BV9V9 |
| Best Sellers Rank | #56,647 in Arts, Crafts & Sewing ( See Top 100 in Arts, Crafts & Sewing ) #182 in Sewing Pillow Forms & Foam #256 in Craft Foam |
| Brand | Fiberglass Supply Depot |
| Brand Name | Fiberglass Supply Depot |
| Coverage | 4 cubic feet |
| Customer Reviews | 4.6 out of 5 stars 59 Reviews |
| Manufacturer | Fiberglass Supply Depot Inc. |
| Manufacturer Part Number | poly4lb2gk |
| Material | Foam,Resin |
| Material Type | Foam,Resin |
| Model Number | 819794022927 |
| Number of Items | 2 |
| Number of Packs | 2 |
| Recommended Uses For Product | Flotation, Soundproofing, Insulation, Filling Voids, Sculpting, Casting |
| UPC | 819794022927 |
| Unit Count | 1 Count |

## Product Details

- **Material:** Foam,Resin
- **Brand:** Fiberglass Supply Depot
- **Manufacturer:** Fiberglass Supply Depot Inc.
- **UPC:** 819794022927

## Images

![Fiberglass Supply Depot 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethan... - Image 1](https://m.media-amazon.com/images/I/61Vgv9wS7SL.jpg)
![Fiberglass Supply Depot 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethan... - Image 2](https://m.media-amazon.com/images/I/8189VtbwU2L.jpg)
![Fiberglass Supply Depot 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethan... - Image 3](https://m.media-amazon.com/images/I/71Gbm9XW+IL.jpg)
![Fiberglass Supply Depot 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethan... - Image 4](https://m.media-amazon.com/images/I/71Jn4WV0S0L.jpg)
![Fiberglass Supply Depot 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethan... - Image 5](https://m.media-amazon.com/images/I/81mbAHsaZfL.jpg)

## Questions & Answers

**Q: The description says that it can be used as insulation. Do you have a recommended sprayer vendor and/or setup?**
A: think it would be hard to spray..pour it in cavities surrounding a fuel tank .. its water prove and floatation,

**Q: For the 2 gallon 4 lbs. density kit, how many pounds of flotation would it nominally provide?**
A: Buoyancy of 2lb foam is 60lbs of flotation per cubic feet. 
Buoyancy of 4lb foam is 30lbs of flotation per cubic feet. 
Remember this is an approximate number.

**Q: i'm new at this.what does density mean i see 2lb 4lb 6lb? thanks**
A: the weight rating numbers are for how much the foam expands and how much weight it can support.  2lb foam will expand around 30 times its liquid amount and 4lb expands around 15 times its liquid amount and 6lb expands 10 times its liquid amount. for my boat i used 4lb it worked great.

**Q: I am restoring old plaster life-size statues for a museum. Could I use your foam product to cast hands in an alginate mold?**
A: The mold would have to be rigid because as the foam expands it could deform your shape if it wasn't.  Also this stuff sticks to everything so make sure you will be able to get it out of your mold.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Expanding Foam
*by G***R on June 1, 2026*

Product works as described Using on motor coach void areas

### ⭐⭐⭐⭐⭐ Be mindful of temperature
*by T***S on June 26, 2026*

I used this to repair some damage to a classic 13 Boston whaler. I actually redid the floor and have a word of advice for anyone new to this type of product. Prep your area well and understand the impact ambient temperature has on this foam. While liquid and while mixing/pouring this foam sticks to everything. EVERYTHING. I use masking tape and those cheap brown rolls of contractor paper to make sure the only thing exposed to the foam before and after expansion is the hole I’m pouring into. Regarding the temperature: the hotter it is outside the faster the foam mixes and needs to be poured. Also the hotter it is outside the more your foam will expand overall. I tried filling a small hole on a 70 degree day and the foam performed well. I thought….. the next week I filled a similar sized hole and used the same amount of foam. Only difference was the temperature outside was in the 90’s. I had the foam expand at least twice as far and ooze out all over the place. Just be mindful of them temp and as expensive as this foam is I suggest doing it on the hottest days you can so that you get the most expansion.

### ⭐⭐⭐⭐⭐ Follow the directions
*by T***H on September 20, 2025*

Good stuff. Works well. Read the direction AND HEED THEM! (It hardens FAST)

## 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 (2 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 United States of America*
*Store origin: US*
*Last updated: 2026-07-06*