--- product_id: 273973809 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 (1 Gallon Kit)" brand: "fiberglass supply depot" price: "¥40177" currency: JPY in_stock: true reviews_count: 13 category: "Fiberglass Supply Depot" url: https://www.desertcart.jp/products/273973809-fiberglass-supply-depot-4-lb-density-expanding-pour-foam-2 store_origin: JP region: Japan --- # 2-part polyurethane for strong, closed-cell foam 5 min full expansion time 4 lb density for superior flotation 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 (1 Gallon Kit) **Brand:** fiberglass supply depot **Price:** ¥40177 **Availability:** ✅ In Stock ## Summary > 🛠️ Elevate your build 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 (1 Gallon Kit) by fiberglass supply depot - **How much does it cost?** ¥40177 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.jp](https://www.desertcart.jp/products/273973809-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 Ready:** Cured foam laminates seamlessly with polyester, epoxy, or vinyl ester without damage. - • **Speedy Setup:** Expands fully in just 5 minutes to keep your projects moving fast. - • **Versatile Mastery:** Perfect for soundproofing, insulation, sculpting, and filling voids—one kit, endless possibilities. - • **Float Above the Rest:** 4 lb density foam delivers unmatched buoyancy for boats and docks. - • **Precision Performance:** Exact 1:1 mixing ratio ensures consistent, reliable results every time. ## Overview Fiberglass Supply Depot’s 4 lb density expanding pour foam is a 2-part polyurethane closed-cell liquid foam kit that produces 2 cubic feet of durable, buoyant material. Ideal for boat and dock flotation, soundproofing, insulation, and filling voids, it cures quickly in about 5 minutes and can be laminated with various resins without melting, making it a versatile solution for professional-grade projects. ## Description desertcart.com: 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 (1 Gallon Kit) : Industrial & Scientific Review: You best be quick! - Good product but on a hot day it goes off QUICK! I used this to backfill fiberglass pool steps that were cracked. I learned on the first mix to not do a lot. The idea was to pour it into the holes I drilled into the stairs that would be patched after. Nope. I had about 3 seconds to get it into the hole as it started going off and most of it would up on the stair. I went out and got funnels for each hole, mixed for 10 seconds and removed the funnel fast. This was better. Review: Perfect - Works ## 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 | |---------------|-------| | ASIN | B08T2195F8 | | Best Sellers Rank | #19,099 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #51 in Urethane Adhesives | | Brand | Fiberglass Supply Depot | | Brand Name | Fiberglass Supply Depot | | Coverage | 2 cubic feet | | Customer Reviews | 4.6 out of 5 stars 496 Reviews | | Manufacturer | Fiberglass Supply Depot Inc. | | Manufacturer Part Number | FBAPOLY4LBGK | | Material | Foam,Resin | | Material Type | Foam,Resin | | Number of Items | 1 | | Number of Packs | 1 | | Recommended Uses For Product | Flotation, Soundproofing, Insulation, Filling Voids, Sculpting, Casting | | UPC | 819794022934 | | Unit Count | 192 Fluid Ounces | ## Product Details - **Brand:** Fiberglass Supply Depot - **Manufacturer:** Fiberglass Supply Depot Inc. - **Material:** Foam,Resin - **Number of Packs:** 1 - **Recommended Uses For Product:** Flotation, Soundproofing, Insulation, Filling Voids, Sculpting, Casting ## 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 (1 Gallon Kit) - Image 1](https://m.media-amazon.com/images/I/611pMIJrAfL.jpg) ## Available Options This product comes in different **Size** options. ## 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 ### ⭐⭐⭐⭐⭐ You best be quick! *by M***W on June 7, 2026* Good product but on a hot day it goes off QUICK! I used this to backfill fiberglass pool steps that were cracked. I learned on the first mix to not do a lot. The idea was to pour it into the holes I drilled into the stairs that would be patched after. Nope. I had about 3 seconds to get it into the hole as it started going off and most of it would up on the stair. I went out and got funnels for each hole, mixed for 10 seconds and removed the funnel fast. This was better. ### ⭐⭐⭐⭐⭐ Perfect *by A***R on August 12, 2026* Works ### ⭐⭐⭐⭐⭐ This is the best foam ever!!! *by D***N on January 19, 2026* I used the 4 lb foam to make a custom dress form, it did well with a plaster cast you’ll want to paint the inside of the cast with latex paint and use mold release first. The foam is nice and dense! It sands well by hand or with an orbital sander. And it paints well too. You will NEED to use a mixing attachment for your drill!! I tried to mix by hand for a little batch and it did not foam up as much. You will also want to work within the temperature range. If you follow what it says to do it will expand 15x its size. I have bought this 3 times for 2 different custom projects and I will buy again! ## 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) - Custom Shop Paint Mixing Cups Plastic Measuring Cup Epoxy Resin, Disposable or Reusable, 32-Ounce Quart - Pack of 12 - Graduated, Mixing Ratios, Automotive Painting Acrylic Art Crafts Kitchen - 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) --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.jp/products/273973809-fiberglass-supply-depot-4-lb-density-expanding-pour-foam-2](https://www.desertcart.jp/products/273973809-fiberglass-supply-depot-4-lb-density-expanding-pour-foam-2) --- *Product available on Desertcart Japan* *Store origin: JP* *Last updated: 2026-10-16*