---
product_id: 766162487
title: "Fiberglass Supply Depot 4 Pounds. Density Expansion Foam, 2-Part PU Closed Cell Liquid Foam for Boat Flotation and Dock, Acoustic Insulation, Vaz Fill"
brand: "fiberglass supply depot"
price: "$206.08"
currency: USD
in_stock: true
category: "Fiberglass Supply Depot"
url: https://www.desertcart.us/products/766162487-fiberglass-supply-depot-4-pounds-density-expansion-foam-2-part
store_origin: US
region: United States of America
---

# Closed-cell foam for superior soundproofing 45 sec working time, 5 min full expansion 4 lb/ft³ density for robust flotation Fiberglass Supply Depot 4 Pounds. Density Expansion Foam, 2-Part PU Closed Cell Liquid Foam for Boat Flotation and Dock, Acoustic Insulation, Vaz Fill

**Brand:** fiberglass supply depot
**Price:** $206.08
**Availability:** ✅ In Stock

## Summary

> 🛠️ Float, Fill, and Fortify with Foam That Means Business!

## Quick Answers

- **What is this?** Fiberglass Supply Depot 4 Pounds. Density Expansion Foam, 2-Part PU Closed Cell Liquid Foam for Boat Flotation and Dock, Acoustic Insulation, Vaz Fill by fiberglass supply depot
- **How much does it cost?** $206.08 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/766162487-fiberglass-supply-depot-4-pounds-density-expansion-foam-2-part)

## 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

- • **Premium 4LB Density:** Engineered to support light to moderate loads—perfect for boat decks and gas tank supports.
- • **Versatile Multi-Use:** Ideal for flotation, acoustic insulation, taxidermy, sculpting, and casting—one foam to rule them all.
- • **Rapid Expansion Formula:** Mix equal parts and watch it fully expand in just 5 minutes, optimizing your workflow.
- • **Resin-Compatible Finish:** Seamlessly laminates with polyester, epoxy, or vinyl ester resins without melting or warping.
- • **Temperature-Smart Application:** Best results between 75°-80°F; precise measurement ensures flawless expansion every time.

## Overview

Fiberglass Supply Depot’s 4LB Density Expansion Foam is a high-performance, 2-part closed-cell polyurethane solution designed for superior flotation, soundproofing, and insulation. With a quick 45-second working time and full expansion in 5 minutes, it supports light to moderate loads and is compatible with multiple resin types, making it the go-to foam for boat flotation, acoustic panels, taxidermy, and sculpting applications.

## Description

This 4LB density foam is suitable for most float applications that require more support than that of 2LB offers. This foam is recommended for use on gas tank support and some deck areas. Choose this density if you think the foam will need to withstand light to moderate loads. The density of 4LB also works well in floating bait or taxidermy applications, as well as many other sculpting, casting, notching and other filling applications.

## Features

- Flotation Foam is a 2-part polyurethane foam that, when mixed in equal parts and put in place, this foam will be soundproof, insulate or provide extra buoyancy.
- 4 lbs. Quart Density Polyurethane Flotation Foam Kit; Consists of 1 Liter of Part A and 1 Liter of Part B and produces 1/2 cubic foot.
- Once fully cured, this foam can be laminated with any type of polyester, epoxy or vinyl ester resin without melting.
- 4LB density also works well in floating bait or taxidermy applications, as well as many other sculpting, casting, carving and other filling applications.
- All provided expansion rates and times are temperature critical. Temperatures below 75° F will decrease the expansion rate, therefore requiring more foam. Ideal working temperature is 75° to 80° F or higher. Accurate measurement 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 |
| Brand Name | Fiberglass Supply Depot |
| Color | Clear |
| Container Type | Can |
| Customer Reviews | 4.4 4.4 out of 5 stars (140) |
| Item Form | Liquid |
| Item Package Quantity | 1 |
| Manufacturer | Fiberglass Supply Depot Inc. |
| Material Type | Foam, Resin |
| Number of Pieces | 2 |
| Other Special Features of the Product | Heat Resistant, Versatile |
| Part Number | poly4lbqk |
| Specific Uses For Product | Flotation, Decoy, Taxidermy, Sculpting, Casting, Carving, Filling |
| UPC | 819794022897 |
| Volume | 1 Quarts |

## Product Details

- **Brand:** Fiberglass Supply Depot
- **Item form:** Liquid
- **Material:** Foam, Resin
- **Special features:** Heat Resistant, Versatile
- **Specific uses for product:** Flotation, Decoy, Taxidermy, Sculpting, Casting, Carving, Filling

## Images

![Fiberglass Supply Depot 4 Pounds. Density Expansion Foam, 2-Part PU Closed Cell Liquid Foam for Boat Flotation and Dock, Acoustic Insulation, Vaz Fill - 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

## 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 United States of America*
*Store origin: US*
*Last updated: 2026-07-14*