---
product_id: 273973810
title: "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 (Quart Kit)"
brand: "fiberglass supply depot"
price: "39224 Ft"
currency: HUF
in_stock: true
reviews_count: 8
category: "Fiberglass Supply Depot"
url: https://www.desertcart.hu/products/273973810-fiberglass-supply-depot-4-lb-density-expanding-pour-foam-2
store_origin: HU
region: Hungary
---

# Closed-cell waterproof foam for flotation 5 min full cure time for fast results 4 lb density for firm, durable foam 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 (Quart Kit)

**Brand:** fiberglass supply depot
**Price:** 39224 Ft
**Availability:** ✅ In Stock

## Summary

> 🚀 Expand Your Potential with Foam That Floats, Fills, and Fortifies!

## Quick Answers

- **What is this?** 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 (Quart Kit) by fiberglass supply depot
- **How much does it cost?** 39224 Ft with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.hu](https://www.desertcart.hu/products/273973810-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

- • **Rapid 5-Minute Cure Time:** Get your projects done faster with a quick-setting formula that expands and solidifies in minutes.
- • **Versatile Multi-Use Formula:** Ideal for soundproofing, insulation, filling voids, sculpting, and even taxidermy projects.
- • **Professional-Grade Compatibility:** Can be laminated with polyester, epoxy, or vinyl ester resins without melting—engineered for expert finishes.
- • **Waterproof Closed-Cell Structure:** Ensures long-lasting buoyancy and moisture resistance, perfect for marine and outdoor use.
- • **Precision Engineered 4 lb Density:** Delivers superior firmness and stability for demanding applications like boat flotation and soundproofing.

## Overview

Fiberglass Supply Depot’s 4 lb density expanding pour foam is a two-part polyurethane closed-cell liquid foam designed for professional-grade flotation, soundproofing, insulation, and filling applications. It cures in just 5 minutes, creating a firm, waterproof foam that can be laminated with various resins, making it a versatile solution for boat docks, kayaks, and advanced DIY projects.

## Description

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 (Quart Kit): desertcart.com: Industrial & Scientific

Review: Great product! Directions a bit off. - This works great and made a nice, firm filler that I needed for a place on my kayak. It was easily sand-able and paintable. It is firmer/stiffer than the spray foam you buy in cans at the home improvement store. Just be aware that the directions are a bit off. In the video we watched online, it looked as if it foamed up instantly, and the directions said to count a number of seconds and no more before pouring. Our experience was that it took a bit longer for it to foam up, and we wasted some that poured through some holes in the cavity we were trying to fill. I would say an extra 10-15 seconds would have worked better.
Review: Works as described! - I purchased this product to secure a fuel tank in a boat. It worked perfectly. I carefully followed the instructions, adding part A to part B (not the other way around), working in an ambient temperature of about 70 degrees Fahrenheit. It expanded slowly over a few minutes and did not "explode" as described by others. The instructions emphasize the mixing order, and I suspect that is the key to avoiding disaster.

## 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 Quart Kit; Consists of 1 pint of Part A and 1 pint of Part B and produces 1/2 cubic foot.
- 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 | B08T255GS5 |
| Best Sellers Rank | #49,618 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #74 in Urethane Adhesives |
| Brand Name | Fiberglass Supply Depot |
| Color | Black, Clear, Yellow |
| Compatible Material | Vinyl |
| Container Type | Bottle |
| Customer Reviews | 4.3 out of 5 stars 118 Reviews |
| Full Cure Time | 5 Minutes |
| Item Form | Liquid |
| Item Package Quantity | 1 |
| Manufacturer | Fiberglass Supply Depot Inc. |
| Material Type | Foam,Resin |
| UPC | 819794022897 |
| Unit Count | 64.0 Ounce |
| Viscosity | Medium to High Viscosity |
| Volume | 1 Quarts |
| Water Resistance Level | Waterproof |

## Product Details

- **Brand:** Fiberglass Supply Depot
- **Material:** Foam,Resin
- **Item Form:** Liquid
- **Color:** Black, Clear, Yellow
- **Item Package Quantity:** 1

## Images

![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 (Quart Kit) - Image 1](https://m.media-amazon.com/images/I/81XhbU5HAlL.jpg)

## Questions & Answers

**Q: What is the cure time?  I see 5 minute until "full expansion" but nowhere on the package do I find the cure time.**
A: Around 30-60 minutes

**Q: If one doesn't use the whole kit how long will the 2 parts last?**
A: As long as you make them.

**Q: would this provide floatation if used in the bow of a kayak?**
A: Yes, that is one of its intended uses. It is a closed cell foam.

**Q: Question any way to pump this? I have a void under a concrete walkway and I need to get it back 4 feet The void is 4x4 and 2 to 6 inches deep.**
A: You only have a brown 30 seconds after you mix the product to put it in the location that you are wanting depending on temperature if you have a mixing tip then you could pump it however it needs to be agitated for 20 seconds

## Customer Reviews

### ⭐⭐⭐⭐⭐ Great product! Directions a bit off.
*by J***. on August 3, 2024*

This works great and made a nice, firm filler that I needed for a place on my kayak. It was easily sand-able and paintable. It is firmer/stiffer than the spray foam you buy in cans at the home improvement store. Just be aware that the directions are a bit off. In the video we watched online, it looked as if it foamed up instantly, and the directions said to count a number of seconds and no more before pouring. Our experience was that it took a bit longer for it to foam up, and we wasted some that poured through some holes in the cavity we were trying to fill. I would say an extra 10-15 seconds would have worked better.

### ⭐⭐⭐⭐⭐ Works as described!
*by R***D on October 21, 2024*

I purchased this product to secure a fuel tank in a boat. It worked perfectly. I carefully followed the instructions, adding part A to part B (not the other way around), working in an ambient temperature of about 70 degrees Fahrenheit. It expanded slowly over a few minutes and did not "explode" as described by others. The instructions emphasize the mixing order, and I suspect that is the key to avoiding disaster.

### ⭐⭐⭐⭐⭐ Expanding Foam.
*by E***S on July 21, 2025*

Easy to use windsurfing board repair foam. This is perfect if you get a soft deck or have to repair a large gouge in your board.

## 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 (Quart Kit)
- Fiberglass Supply Depot 6LB Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boats, Dock Flotation, Carving, Soundproofing, Filling Voids, and Insulation (Quart Kit)
- 2 Lb Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (Quart Kit)

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*Product available on Desertcart Hungary*
*Store origin: HU*
*Last updated: 2026-01-24*