How To Use Flex Seal Extreme Liquid 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 in a Tube
- Prepare Surfaces: Clean and dry application surfaces, removing any dirt, grease, or oil with a degreaser. Do not use alcohol or any other 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 Extreme Liquid Epoxy 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 Extreme Liquid Epoxy in a Syringe
- Prepare Surfaces: Clean and dry application surfaces, removing any dirt, grease, or oil with a degreaser. Do not use alcohol or any other 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. Use the mixing stick and mix until full blended and uniform in color (approx. 1 minute).
- Apply & Join: Apply the mixed epoxy to one surface, press parts firmly together, and clamp heavy objects (if necessary). Open work time is 45 minutes.
Can I Apply Flex Seal Epoxy on Wet Surfaces or Underwater?
Flex Seal Extreme Liquid Epoxy forms a durable, waterproof barrier once sealed; however, it will not work on wet surfaces or underwater.
How Long Does it Take for Flex Seal Epoxy To Dry?
Flex Seal Extreme Liquid Epoxy sets at room temperature in 3-10 hours and fully cures in 15-24 hours.
What Are The Different Types of Flex Seal Epoxy?
Flex Seal Epoxy is available in Extreme Liquid
Flex Seal Extreme Liquid Epoxy is a multi-purpose, rapid-cure adhesive with a non-sag formula, making it 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. Once cured, it can be tooled, shaped, sanded, painted, and drilled for a seamless finish.
Our Extreme Liquid formula is available in a 25mL Syringe or a 14mL Squeeze Tube (2-Pack).
What Color is Flex Seal Epoxy?
Flex Seal Extreme Liquid Epoxy is available in Black.
Flex Seal Epoxy Helpful Hints
Product Attributes
- Tensile strength up to 6,000 PSI — strong enough to lift over 16,000 lbs.
- Resistant to high temperatures (up to 550°F)
- Excellent chemical and fuel resistance (once cured)
- Suitable for vertical & overhead applications
- Once mixed, will begin to thicken or gel in approximately 25-45 minutes
- Paintable (high-quality latex paints recommended)
- Can be sanded, and drilled
- Seals gaps and cracks
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 mild solvent
Cured: Remove mechanically (e.g., sanding)
How Do I Store Flex Seal Epoxy?
Storing Extreme Liquid Epoxy 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 Epoxy in a Syringe: Pull the plunger back slightly, wipe the nozzle clean and replace the “Snap & Save” cap securely to prevent drying. Remove excess epoxy with a clean, dry cloth.
To increase the life of your Flex Seal Epoxy, it is recommended you store it in a climate-controlled area between 60°F and 100°F. Avoid exposure to direct sunlight and moisture.
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.