--- product_id: 214989981 title: "Flex Paste, Waterproof Paintable Putty, Spackle Sealant, Fill Gaps Cracks Holes - Block Out Water and Air - UV Resistant - Walls, Drywall, EPDM, Concrete, Roof, RV Repairs, Black, Cartridge" brand: "flex paste" price: "£18.83" currency: GBP in_stock: true reviews_count: 13 category: "Flex Paste" url: https://www.desertcart.co.uk/products/214989981-flex-paste-waterproof-paintable-putty-spackle-sealant-fill-gaps-cracks store_origin: GB region: United Kingdom --- # Fully paintable & UV resistant Waterproof & cures underwater 9 oz cartridge - perfect for precise application Flex Paste, Waterproof Paintable Putty, Spackle Sealant, Fill Gaps Cracks Holes - Block Out Water and Air - UV Resistant - Walls, Drywall, EPDM, Concrete, Roof, RV Repairs, Black, Cartridge **Brand:** flex paste **Price:** £18.83 **Availability:** ✅ In Stock ## Summary > 💪 Seal it. Flex it. Forget leaks forever. ## Quick Answers - **What is this?** Flex Paste, Waterproof Paintable Putty, Spackle Sealant, Fill Gaps Cracks Holes - Block Out Water and Air - UV Resistant - Walls, Drywall, EPDM, Concrete, Roof, RV Repairs, Black, Cartridge by flex paste - **How much does it cost?** £18.83 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.co.uk](https://www.desertcart.co.uk/products/214989981-flex-paste-waterproof-paintable-putty-spackle-sealant-fill-gaps-cracks) ## Best For - flex paste enthusiasts ## Why This Product - Trusted flex paste brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Seal Like a Pro:** Creates a flexible, watertight rubberized barrier that blocks air, water, and moisture. - • **Custom Finish Ready:** Paintable after curing to match any décor while preventing rust and UV damage. - • **Big Gaps? No Problem:** Super thick paste instantly fills large cracks, holes, and gaps with no shrinkage or cracking. - • **Stay Fresh Container:** Innovative airtight packaging locks in freshness and sealing power—no waste, no fuss. - • **Apply Anywhere, Anytime:** Works on wet or dry surfaces—including underwater—no waiting required. ## Overview Flex Paste is a premium waterproof, paintable putty designed for professional-grade sealing and repairs. Its thick, rubberized formula adheres to a wide range of surfaces—including wood, concrete, metal, and even underwater applications—creating a flexible, durable barrier that blocks air, water, and moisture. Packaged in an airtight container to maintain freshness and performance, Flex Paste is perfect for filling large gaps, cracks, and holes, and can be painted over once cured for a seamless finish. Ideal for indoor and outdoor use, it resists UV damage and prevents rust, making it a must-have for millennial managers who demand reliable, long-lasting home and DIY solutions. ## Description Product description Works indoors and outdoors. Penetrates deep to seal out air, water, and moisture. Once dry, it turns into a strong, flexible, watertight, rubberized barrier. Apply to almost any surface. Use on: Wood, glass, tile, concrete, aluminum, metal, brick, stucco, masonry, PVC and so much more. Clings to wet and dry surfaces. Even underwater. No need to wait for surfaces to completely dry before sealing them. It even cures underwater. Can be spread, shaped, and formed. This thick rubberized paste is exceptional for all types of crafts, hobbies, and more. Won’t shrink, crack, or become brittle. Flex Paste stays completely flexible, making it perfect for all-season roof repairs and all types of DIY projects. Made in the USA Flex Paste is proudly made in America, using globally sourced products. DIRECTIONS Using putty knife, trowel or similar tool, remove an even layer from the top surface. Do not scoop deeply into the tub as this may create air pockets. Apply a generous amount to the surface using a smooth motion. Always make sure all cracks & holes have been completely filled & cured before testing. Review: Perfect water sealant with no leaks on cracked items - I had an outdoor water fountain that I forgot had water in it and it froze.... Which made the whole fixture crack at the water expanded. I use this flex paint to see if it would be able to seal the cracks and hold the water and it did!!! No more leaks and i the adhesion holds really really well. Drives fairly quickly like maybe 24 hours. The smell is a little strong so I would let it sit outside as it dries. Review: Good stuff, simple to use - I was worried bjt, it worked I repaired a fiberglass bathtub, it was thick, I globed it on and to worked good, my can was air tight and fresh, not permanent but long lasting patch, don't get it on your clothes,,, ## Features - NEW! STAY FRESH CONTAINER – Blocks out air and locks in freshness to extend the sealing power of Flex Paste, with no waste - COAT, SEAL & PROTECT - Penetrates deep to seal out air, water, and moisture. Once dry, it turns into a strong, flexible, watertight, rubberized barrier - WORKS UNDERWATER - Can be applied underwater, and it even dries underwater - FILLS LARGE AREAS - Super thick rubber paste clings to the surface and instantly fills large gaps, cracks, and holes - FULLY PAINTABLE - Once fully cured, it can be painted any color. Helps prevent rust and corrosion, and it is UV resistant ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B084TDD2FB | | Best Sellers Rank | #7,205 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #27 in Hardware Sealers | | Brand | Flex Paste | | Brand Name | Flex Paste | | Color | Black | | Compatible Material | Wood, Glass, Tile, Concrete, Aluminum, Metal, Stucco, Masonry, Copper, Fabric, Fiberglass, Ceramic, Porcelain, Natural Stones, Roofing, Pvc, Eifs, Cspe, Epdm, Hypalon Polyurethanes | | Customer Reviews | 4.0 out of 5 stars 6,016 Reviews | | Included Components | Household Item | | Item Dimensions | 11.25 x 3 x 3 inches | | Item Form | Paste | | Item Type Name | Flex Paste 9 Oz. Cartridge - Black | | Item Weight | 9 Ounces | | Item dimensions L x W x H | 11.25 x 3 x 3 inches | | Manufacturer | Swift Response, LLC | | Material | Rubber | | Material Type | Rubber | | Model | FLEX SEAL - PFSBLKR10 - BLACK | | Number of Items | 1 | | Part Number | PFSBLKR10 | | Style | 9 oz Black | | Style Name | 9 oz Black | | Surface Recommendation | Windows,Doors | | UPC | 850010226859 | | Unit Count | 1.0 Ounce | | Warranty Description | 1 Year Limited | | Water Resistance Level | Waterproof | ## Product Details - **Brand:** Flex Paste - **Item Weight:** 9 Ounces - **Item dimensions L x W x H:** 11.25 x 3 x 3 inches - **Material:** Rubber - **Style:** 9 oz Black ## Images ![Flex Paste, Waterproof Paintable Putty, Spackle Sealant, Fill Gaps Cracks Holes - Block Out Water and Air - UV Resistant - Walls, Drywall, EPDM, Concrete, Roof, RV Repairs, Black, Cartridge - Image 1](https://m.media-amazon.com/images/I/51h83Yv5HdL.jpg) ![Flex Paste, Waterproof Paintable Putty, Spackle Sealant, Fill Gaps Cracks Holes - Block Out Water and Air - UV Resistant - Walls, Drywall, EPDM, Concrete, Roof, RV Repairs, Black, Cartridge - Image 2](https://m.media-amazon.com/images/I/71id8yOrn8L.jpg) ![Flex Paste, Waterproof Paintable Putty, Spackle Sealant, Fill Gaps Cracks Holes - Block Out Water and Air - UV Resistant - Walls, Drywall, EPDM, Concrete, Roof, RV Repairs, Black, Cartridge - Image 3](https://m.media-amazon.com/images/I/71yd+Gnyk+L.jpg) ![Flex Paste, Waterproof Paintable Putty, Spackle Sealant, Fill Gaps Cracks Holes - Block Out Water and Air - UV Resistant - Walls, Drywall, EPDM, Concrete, Roof, RV Repairs, Black, Cartridge - Image 4](https://m.media-amazon.com/images/I/71xvXuxwrIL.jpg) ![Flex Paste, Waterproof Paintable Putty, Spackle Sealant, Fill Gaps Cracks Holes - Block Out Water and Air - UV Resistant - Walls, Drywall, EPDM, Concrete, Roof, RV Repairs, Black, Cartridge - Image 5](https://m.media-amazon.com/images/I/71mAPcut5pL.jpg) ## Available Options This product comes in different **Color, Size** options. ## Questions & Answers **Q: Can I use it around the base of my toilet?** A: You can! We recommend keeping it near the base of the toilet and not spreading it through the floor as it can become slippery when wet. Let us know how the project goes! **Q: can flex glue be used to repair a roho inflatable neoprene wheelchair cushion?** A: not sure, they make a tape like duct tape, that might work. The paste is more for sealing cracks. **Q: can you paint after this is applied?** A: Spray paint might eat the rubber away or anything else that has more of a solvent when you paint I wouldn’t use on this **Q: Will it fix a hole puncture on a 8” subwoofer?** A: Yes read my post about the puncture on my 2016 ford interceptor rear quarter panel worked like a champ on this damage from a corner of a shelf on the wall ## Customer Reviews ### ⭐⭐⭐⭐⭐ Perfect water sealant with no leaks on cracked items *by F***S on December 13, 2025* I had an outdoor water fountain that I forgot had water in it and it froze.... Which made the whole fixture crack at the water expanded. I use this flex paint to see if it would be able to seal the cracks and hold the water and it did!!! No more leaks and i the adhesion holds really really well. Drives fairly quickly like maybe 24 hours. The smell is a little strong so I would let it sit outside as it dries. ### ⭐⭐⭐⭐⭐ Good stuff, simple to use *by L***K on April 18, 2025* I was worried bjt, it worked I repaired a fiberglass bathtub, it was thick, I globed it on and to worked good, my can was air tight and fresh, not permanent but long lasting patch, don't get it on your clothes,,, ### ⭐⭐⭐⭐ Works under any condition *by B***N on September 16, 2024* I want to rate this product lower because this is the second one I’ve bought that had a hard 2/3” top so 10-15% of it is trash. This product is also very hard to work with. This will not spread smooth and is very messy. This product will only patch a small area. I used the entire tub for this small patch over. However, I am rating this product a 4 star because there is not another product that I know of like it. This is the second time patching my rooftop tent due to the tent getting a crack in it. This product went on and cured in the very moist fog. It then rained and still cured. This product lasted through a very cold winter through heavy snow and some rain. This product took abuse from heavy 4x4ing and flexing. It wasn’t until it was well over 100f and with some flexing this product split. I bought this second tub to patch the crack. ## Frequently Bought Together - Flex Paste, Waterproof Paintable Putty, Spackle Sealant, Fill Gaps Cracks Holes - Block Out Water and Air - UV Resistant - Walls, Drywall, EPDM, Concrete, Roof, RV Repairs, Black, Cartridge - Flex Seal 2-Pack Black 17oz Stop Leaks Instantly, Waterproof Sealant Coating For Gutters, RV, Roof, Skylights, Windows - Flex Paste, Waterproof Paintable Putty, Spackle Sealant, Fill Gaps Cracks Holes - Block Out Water and Air - UV Resistant - Walls, Drywall, EPDM, Concrete, Roof, RV Repairs, Black, Half-Quart --- ## 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.co.uk/products/214989981-flex-paste-waterproof-paintable-putty-spackle-sealant-fill-gaps-cracks](https://www.desertcart.co.uk/products/214989981-flex-paste-waterproof-paintable-putty-spackle-sealant-fill-gaps-cracks) --- *Product available on Desertcart United Kingdom* *Store origin: GB* *Last updated: 2026-06-20*