How To Use Flex Seal Epoxy
From getting started to cleaning up, this article will show you how to use Flex Seal Epoxy safely and correctly for your projects and repairs.
Getting ready to use Flex Seal Epoxy.
How to properly apply Flex Seal Epoxy.
Using on wet surfaces or underwater.
What color is Flex Seal Epoxy?
How to clean up Flex Seal Epoxy.
Getting Ready To Use Flex Seal Epoxy
Materials Needed:
• Protective gloves, clothing and eyewear
• Cloth/rag or Paper towels
• Plastic covering, drop cloth, or tarp
IMPORTANT: Before using Flex Seal Epoxy, read all directions carefully and take proper safety precautions, such as being in a well-ventilated area and wearing protective gear.
Protect areas you don’t want to get Flex Seal Epoxy on by protecting your work surface with a drop cloth or disposable covering.
To get the most out of Flex Seal Epoxy, READ THE DIRECTIONS CAREFULLY. Then, follow along with this blog for a comprehensive step-by-step guide.
How Do I Apply Flex Seal Epoxy?
Applying Flex Seal Epoxy — Extreme Liquid in a Tube
- Prepare Surfaces: Clean and dry application surfaces, removing any dirt, grease, or oil with a degreaser. Do not use alcohol or cleaners that may leave a petroleum residue. If the surface has rust, use sandpaper to remove.
- Dispense & Mix: Dispense equal parts of resin and catalyst from each tube onto the included plastic tray or a clean, disposable surface. Mix thoroughly until the color is uniform (approx. 1 minute).
- Apply & Join: Quickly apply the mixed epoxy to one surface, press parts firmly together, and clamp heavy objects (if necessary).
- Cure: Allow Flex Seal Epoxy—Extreme Liquid to cure undisturbed. It will set in 3–10 hours at room temperature and fully cure in 15–24 hours, or as fast as 1 hour with heat.
Applying Flex Seal Epoxy — Extreme Liquid in a Syringe
- Prepare Surfaces: Clean and dry application surfaces, removing any dirt, grease, or oil with a degreaser. Do not use alcohol or cleaners that may leave a petroleum residue. If the surface has rust, use sandpaper to remove.
- Dispense & Mix: Remove the re-sealable no-waste cap from the syringe and save for later. Push the plunger to dispense equal amounts of resin and hardener onto the included plastic tray or a clean, disposable surface. Mix until fully blended and uniform in color (approx. 1 minute).
- Apply & Join: Apply the mixed epoxy to one surface, press parts firmly together, and clamp if needed. Open work time is 45 minutes.
- Cure: Allow Flex Seal Extreme Liquid Epoxy to cure undisturbed. It will set in 3–6 hours at room temperature and fully cure in 15–24 hours, or as fast as 1 hour with heat.
Applying Flex Seal Epoxy — Ultimate Putty
- Prepare Surfaces: Protect your work area. Clean and dry surfaces, removing dirt, grease, oil, and rust with sandpaper or a degreaser for the best bond. Do not use alcohol or cleaners that may leave a petroleum residue.
- Cut and Knead: Cut off the desired amount of putty. Knead it by hand until the color is uniform (approx. 1 minute).
- Apply: Press the mixed putty firmly onto the repair surface within 2–3 minutes of mixing. Mold and shape as needed to fill gaps, cracks, or holes.
- Allow to Cure: Sets in 15 minutes, reaches maximum strength in 48 hours.
Once fully cured, the Extreme Liquid and Ultimate Putty formulas can be sanded, drilled, tapped, or painted to match the repair.
Can I Apply Flex Seal Epoxy on Wet Surfaces or Underwater?
Once cured, Flex Seal Epoxy—Extreme Liquid forms a durable, waterproof barrier; however, it will not work on wet surfaces or underwater.
Flex Seal Epoxy—Ultimate Putty can be applied to wet surfaces and even works underwater.
How Long Does It Take for Flex Seal Epoxy to Dry?
Extreme Liquid: Sets at room temperature in 3–6 hours and cures in 15–24 hours.
Ultimate Putty: Sets in 15 minutes and cures in 48 hours.
What Are The Different Types of Flex Seal Epoxy?
Flex Seal Epoxy—Extreme Liquid is a multi-purpose, rapid-cure adhesive with a non-sag formula, ideal for overhead and vertical applications. It can fill gaps and cracks and cures to a permanent, watertight bond. This durable epoxy resists heat, chemicals, and impacts, ensuring long-lasting performance. The Extreme Liquid formula is available in a 25mL Syringe or a 14mL Squeeze Tube (2-Pack).
Flex Seal Epoxy—Ultimate Putty combines the strength of steel with the versatility of putty. It delivers extraordinary strength, creating a bond that can lift and hold 4 tons!* Hand-mixable and easy to use, it's perfect for shaping, molding, or filling gaps. From repairing rust and fixing leaks to patching holes and rebuilding parts, Flex Seal Ultimate Putty Epoxy bonds to virtually any surface. Designed for extreme conditions, it’s heat and chemical-resistant, can be applied to wet surfaces, and even works underwater—providing the ultimate permanent bond. Ultimate Putty is available in a 2-oz stick.
*Lift and strength tests were conducted in controlled environments for demonstration purposes only. Attempting to replicate these tests is extremely dangerous and strongly discouraged. Do not attempt.
What Color is Flex Seal Epoxy?
Extreme Liquid: Cures to black.
Ultimate Putty: Cures to dark gray.
Flex Seal Epoxy: Product Attributes
- Super-strong: Extreme Liquid rated at 6,000 PSI; 1 gram can lift 16,000 lbs.* Ultimate Putty lifts up to 8,000 lbs per 2oz stick.*
- Adheres to most surfaces.
- Forms a durable, waterproof barrier once cured.
- Can be applied to wet surfaces and underwater (Putty only).
- Fills gaps and cracks.
- Fast setting – Extreme Liquid: 3–6 hours. Ultimate Putty: 15 minutes.
- Ideal for overhead and vertical applications.
- Designed for extreme conditions, both indoor and outdoor.
- High-Heat Resistance: Up to 550°F for Liquid and 350°F for Putty once fully cured.
- Impact, chemical, and fuel resistant.
- Simple to mix and apply.
- Once fully cured, can be sanded, drilled, or painted with high-quality latex paints.
*Lift and strength tests were conducted in controlled environments for demonstration purposes only. Do not attempt.
Recommended Application Surfaces:
- Metal
- Glass
- Wood
- PVC
- Ceramic
- Concrete
- Tile
- Fiberglass
- Brick
- Stone
- Rigid Plastics and more
Surfaces to avoid: Polyethylene, Polypropylene, Nylon, Mylar
Important Information About Flex Seal Epoxy:
- Not for flexible joints or moving cracks.
- Not food safe.
- Not aquarium safe.
- Uncured Epoxy should never be exposed to temperatures over 120°F.
- Do not thin Flex Epoxy with solvents, as it prevents curing.
- Product will NOT cure to a flexible coating.
How Do I Clean up Flex Seal Epoxy?
Clean-up (uncured product): Use a mild solvent like denatured alcohol and a clean cloth.
Cured: Remove mechanically (e.g., sanding)
How Do I Store Flex Seal Epoxy?
Storing Extreme Liquid in a Squeeze Tube: Clean the tube nozzle and securely replace the caps to prevent drying. Remove excess epoxy with a clean, dry cloth and acetone or mineral spirits.
Storing Extreme Liquid in a Syringe: Pull the plunger back slightly, wipe the nozzle clean, and replace the “Snap & Save” cap securely. Remove excess epoxy with a clean, dry cloth.
Extreme Liquid should be stored in a cool, dry, climate-controlled area between 50°F and 90°F.
Storing Ultimate Putty: Store in a cool, dry place between 41°F and 77°F, with humidity between 30% and 70%. To prevent contamination, do not return used putty to its original container.
And there you have it. Now you’re ready to use Flex Seal Epoxy for all sorts of DIY projects and repairs. For additional questions or concerns, please visit our FAQ page or contact customer service at 833-411-3539.
