PondScape PUR Black NF - Black Straw Foam 16oz

Professional Black Expanding Foam for Natural-Looking Pond & Waterfall Construction

PondScape PUR Black NF (No Foam Gun) is a premium black polyurethane expanding foam specifically engineered for pond, waterfall, and water feature construction. Unlike standard construction foams that cure to an unnatural tan or yellow color, PUR Black NF expands to a deep black finish that blends seamlessly with rocks, liners, and natural stone—creating invisible, professional-grade seals that disappear into your design.

How It Works

This single-component polyurethane foam comes in a convenient self-dispensing 16 oz can with an attached application straw—no foam gun required. Simply shake the can, attach the straw, and dispense. The foam expands to fill voids, gaps, and irregular spaces between rocks and liner, then cures to a firm, waterproof seal within 24 hours. Once cured, the black foam is UV-resistant, fish-safe, and can be trimmed, carved, or shaped to achieve the perfect finish.

Available Pack Sizes

1 Count (SKU: 95316)
Single 16 oz can ideal for small repairs, touch-ups, or testing the product on a new project. Perfect for minor waterfall adjustments, sealing small gaps, or filling voids in existing installations.

2 Count (SKU: 95317)
Two 16 oz cans provide enough foam for small to medium pond projects or waterfall builds. Great for DIY pond builders working on backyard water gardens or small pondless waterfall features.

6 Count (SKU: 95318)
Six 16 oz cans deliver the coverage needed for medium to large pond installations, multi-tier waterfalls, or stream builds. The go-to choice for serious DIYers and small pond installation businesses.

12 Count (SKU: 95319)
Twelve 16 oz cans provide professional-grade coverage for large-scale projects, commercial installations, or contractors managing multiple job sites. Best value per can for high-volume users.

Key Benefits

• Natural Black Color: Cures to a deep black that blends invisibly with rock and liner
• No Foam Gun Needed: Self-dispensing can with attached straw for easy application
• Waterproof & Fish-Safe: Once cured, completely safe for aquatic life and submersible applications
• UV-Resistant: Won't degrade or discolor from sun exposure
• Excellent Adhesion: Bonds to EPDM liner, PVC, stone, concrete, and most surfaces
• Trimmable & Shapeable: Can be cut, carved, or sculpted after curing for custom finishes
• Fills Irregular Voids: Expands to fill gaps and spaces that are difficult to seal with other methods
• Directs Water Flow: Create custom water channels and guide flow over rocks and features
• Professional Results: Trusted by pond installers and water feature professionals

Application Instructions

Shake can vigorously for 30 seconds before use. Attach the included application straw securely to the valve. Hold can upside down during application for best results. Dispense foam into gaps, voids, or areas where you want to direct water flow. Foam will expand 2-3 times its dispensed volume, so apply conservatively—you can always add more. Allow 24 hours for full cure before exposing to water. Wear gloves during application as uncured foam is sticky and difficult to remove from skin.

Coverage & Yield

Each 16 oz can yields approximately 1.5-2 cubic feet of cured foam, depending on temperature and humidity. Coverage varies based on gap size and application thickness. For reference, one can typically fills 15-20 linear feet of 1-inch gaps or seals 8-12 medium-sized rock placements in a waterfall.

When to Use

Use PUR Black NF during new pond construction to seal liner edges, fill voids between stacked rocks, create water channels in waterfalls, secure boulders in place, or build up stream edges. It's also perfect for retrofitting existing installations—sealing leaks, redirecting water flow, stabilizing loose rocks, or improving the appearance of visible tan foam from previous projects. Apply when temperatures are between 40°F and 90°F for optimal expansion and cure.

Pro Tips for Best Results

Work in sections and allow foam to cure before adding more layers. For large voids, apply in multiple passes rather than one thick application to ensure complete curing. Trim excess foam with a sharp utility knife after it's fully cured (24 hours). For an even more natural look, dust the surface of wet foam with sand or fine gravel before it cures. Always test adhesion on a small area first when working with unusual surfaces.

Frequently Asked Questions

Q: Is this foam safe for fish and aquatic plants?
A: Yes. Once fully cured (24 hours), PUR Black NF is completely inert and safe for all fish, plants, and aquatic life. Do not allow uncured foam to contact pond water.

Q: Do I need a foam gun to use this product?
A: No. PUR Black NF is a "straw foam" that comes with an attached application straw. Simply shake, attach the straw, and dispense. No foam gun required, making it perfect for DIY projects and occasional use.

Q: How much does the foam expand?
A: PUR Black NF expands approximately 2-3 times its dispensed volume. Start with less than you think you need—you can always add more after the first application cures.

Q: Can I use this foam underwater or while water is running?
A: No. Apply foam to dry surfaces only. The foam needs air moisture to cure properly, but standing water will prevent proper adhesion and curing. Drain the area, apply foam, allow 24 hours to cure, then refill.

Q: How long does it take to cure?
A: Surface cure (tack-free) occurs in 30-60 minutes. Full cure takes approximately 24 hours. Cure time varies with temperature, humidity, and foam thickness. Cooler temperatures and low humidity slow curing.

Q: Can I trim or shape the foam after it cures?
A: Absolutely. Once fully cured, PUR Black NF can be cut with a utility knife, carved with a saw, or shaped with a rasp. This allows you to create custom contours and remove excess foam for a clean, professional finish.

Q: Will the black color fade in sunlight?
A: No. PUR Black NF is UV-resistant and formulated to maintain its black color even with continuous sun exposure. Unlike tan foams that yellow over time, this stays black.

Q: What's the difference between this and regular construction foam?
A: Regular construction foam cures to tan or yellow, making it highly visible in pond applications. PUR Black NF is specifically formulated for water features with a black color, superior UV resistance, and fish-safe formulation once cured.

Q: How many cans do I need for my project?
A: It depends on your project size. For a small backyard waterfall (3-4 tiers), 2-6 cans is typical. Medium ponds with waterfalls may need 6-12 cans. Large installations or commercial projects may require 12+ cans. Order extra—it's better to have too much than run out mid-project.

Q: Can I use this to repair leaks in my existing pond?
A: Yes, but with limitations. PUR Black NF works well for filling voids and gaps that cause water to bypass your waterfall or stream. For actual liner punctures or tears, use a proper liner patch kit first, then use foam to seal around the repair if needed.

Q: What temperature should it be for application?
A: Apply when air temperature is between 40°F and 90°F. The can should also be at room temperature (60-75°F) for best results. Cold cans produce less expansion; warm cans expand more aggressively.

Q: How do I remove uncured foam from my hands or tools?
A: Wear gloves! Uncured foam is very sticky. If you get it on skin, wipe immediately with a dry cloth, then clean with acetone or foam cleaner. Once cured on skin, it must wear off naturally (3-5 days). Clean tools immediately with acetone or foam gun cleaner.