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🛠️ Float, fill, and fix faster — foam that works as hard as you do!
This 4 lb density expanding pour foam is a two-part polyurethane closed-cell liquid foam kit designed for boat and dock flotation, soundproofing, insulation, and filling voids. It cures fully in 5 minutes, producing a durable, waterproof foam that can be laminated with various resins. Ideal for professionals needing fast, reliable, and versatile foam solutions with superior buoyancy and structural integrity.










| ASIN | B08T255GS5 |
| Best Sellers Rank | #28,782 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #61 in Urethane Adhesives |
| Brand | Fiberglass Supply Depot |
| Brand Name | Fiberglass Supply Depot |
| Color | Black, Clear, Yellow |
| Compatible Material | Vinyl |
| Container Type | Bottle |
| Customer Reviews | 4.4 out of 5 stars 146 Reviews |
| Full Cure Time | 5 Minutes |
| Item Form | Liquid |
| Item Package Quantity | 1 |
| Manufacturer | Fiberglass Supply Depot Inc. |
| Material | Foam , Resin |
| Material Type | Foam,Resin |
| Number of Pieces | 2 |
| Other Special Features of the Product | Versatility |
| Part Number | poly4lbqk |
| Special Feature | Versatility |
| Specific Uses For Product | Floating Decoy, Taxidermy |
| UPC | 819794022897 |
| Unit Count | 64.0 Ounce |
| Viscosity Level | Medium to High |
| Volume | 1 Quarts |
| Water Resistance Level | Waterproof |
C**S
2part foam
The foam is exactly what I needed. It worked perfectly. Awesome product.
J**.
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.
T**S
Expands quickly
I created a rear wing which was hollow and needed to strong as it is active and used as an air brake so I needed to fill it with foam. The 4 pound foam was perfect but calculating the internal volume was difficult. To be sure I wasn't going to come up short I added a little extra and did two pours. Because of the shape I couldn't see where the first ended so I proceeded to do the second pour. As soon as I saw it I had like 2 seconds before it over flowed. All good as I planned for this and could just cut the excess off. So be warned and prepared if you mixed too much. It sticks to everything and there is no stopping it. My wing now is as hard as a rock and strong so it worked well for me.
M**W
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.
J**.
Taxidermy work
Used for taxidermy purposes. It's a denser foam that does not expand as much as the lighter weight foams, but it has been great for form alterations etc Might be a waste to use for habitat work as you'd get more expansion from the lighter weights.
R**O
Right product
Good product
W**O
Good stuff!
Follow the instructions and work quickly. The foam pours easily after mixing and expands rapidly. Worked perfectly to fill and seal a baseboard area of my pole barn. Best I can tell, the estimated volumes are accurate.
M**T
Solidifies and foams up in a span on 8 seconds
Instructions were unclear and also we're not included so I started off slow poured some in at equal amounts of both solutions with nothing happening so I poured more started to mix and get thick but still barely forming so I figured I'd put all of it into a four gallon bucket started to see it mix more turned around for about ten seconds to prep the area on the wall to fill and I turn back around and it's all just a solid bucket of useless hard unmailable foam no choice at this point but to throw it all away wouldn't recommend if you plan to shape it in any way shape or form
R**B
Good high quality dense foam.
My first use of this stuff was unconventional. I injected it into the failed diaphragm that engaged the front wheel drive of my 05 Suzuki Grand Vitara. Saved me taking the diff all out and apart. Worked great. Is real dense and firm when cured and seems unaffected by oil. My next unconventional use will be doing some shaping to the front of my Smart Car.
S**O
Works perfectly.
Mix and pour FAST! Works great but the expansion time leaves little to no room for error.
B**I
Great for crafts!
This is great for a craft we found on Pinterest!
P**.
4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flo
Does not give the density that I expected. I inserted this foam into PVCt wheels for boat lift. Not worth the money
M**U
Sa gonflé pas fort fort
J'ai mis sa entre mes longerons de bateau et je m'attendais à l'équivalent de 16 litre de mousse comme mentionné sur la bouteille.. Par contre j'en ai eu environ 10 litres.. Je ne suis pas convaincu et je crois que je n'ai pas assez brasser à grande vitesse le mélange.. Donc je devrai en recommander mais Sam semble être un bon produit par contre très coûteux.. Par chance je n'avais pas le bateau au complet à faire!
Trustpilot
4 days ago
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