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Underwater Sealant

(Last Updated On: 2 October 2023)

Underwater Sealant: Adiseal Seals in Water Instantly

Adiseal underwater sealant is a versatile product that can seal in dry, damp, wet and even underwater. Most sealants that require a dry surface to be able to adhere to when applying the sealant. This is not a problem for Adiseal and makes it perfect for both permanent and emergency repairs in various items such as pools, boats, buckets, tanks, tubs, leaking gutters, and felt roofs.

Adiseal underwater sealant can seal instantly.

Sealants suitable for use underwater

Unlike traditional sealants that require dry surfaces for application, Adiseal offers a convenient solution for projects involving water. With other sealants, the water must be removed before application, which can be time-consuming, especially in large water bodies like pools. Adiseal has the ability to be applied to dry, damp or wet surfaces. Even when applied to dry surfaces, not all sealants can effectively seal underwater. They may not maintain their bond when submerged.

Demonstration of an underwater sealant sealing a leak underwater instantly.
Underwater sealant demonstration of sealing leak underwater.

Adiseal is best underwater sealant

To demonstrate the capabilities of Adiseal underwater sealant and adhesive, we used a large plastic tub and cut a large 10mm by 250mm hole in it. It was then filled with a bucket full of water. Despite the water pouring through the sizable hole, Adiseal quickly and effectively sealed the leak, showcasing its exceptional sealing performance underwater. See the high performance of Adiseal in the demonstration video below.

Waterproof sealant sealing underwater.

Best mould resistant sealant test

For a product to successfully seal underwater, it also needs to cure underwater, resist mould growth as well as stay stuck to the material surface. In our pursuit of the best underwater sealant, we conducted comprehensive tests, including a thorough evaluation of mould resistance. The test involved applying various sealants inside new plastic cups, filling them halfway with tap water, and ensuring consistent conditions for fairness. Among all the sealants tested, Adiseal emerged as the top performer with the strongest mould resistance, as illustrated in the accompanying image.

Mould resistant underwater sealant test. Adiseal vs popular competitor. Adiseal has strongest mould resistance underwater.
Strongest mould resistant sealant test results when in water.


Mould resistance test result

Even after 90 days of being underwater in the same tap water, both the sealant & water are still very clear in the Adiseal cup.


Clear sealant

Adiseal Ultra clear sealant & adhesive stands out as a truly transparent option. Unlike other sealants that claim to be clear but result in a cloudy or tinted appearance upon application, Adiseal lives up to its Ultra Clear name. Cheaper silicone clear sealants often exhibit a cloudy, almost white colour instead of providing the desired clarity.


Adiseal Ultra Clear has strongest colour retention underwater

Clear underwater sealant in water comparison. Adiseal Ultra Clear sealant vs *** sealant and adhesive. Adiseal has stayed clear whereas *** sealant and adhesive has turned white.
Colour retention of sealant test in water. Adiseal Ultra Clear vs *** sealant and adhesive.

Adiseal also excels in maintaining its colour even when submerged underwater. The accompanying image clearly demonstrates that while the competitor’s clear product has turned white, Adiseal has retained its clarity and transparency even when submerged underwater for over 16 days.


Colour retention test

The colour retention test involved multiple clear sealants from various manufacturers. Each product was applied inside new, clean plastic cups, filled halfway with water, covered, and kept under identical conditions for fairness.

Clear sealant clarity retention test in water. Adiseal remained the most clear.
Clearest sealant test results when sealant were kept in water.


Colour retention test result

Adiseal was the only product to stay clear above & underwater, making it ideal for use as an underwater clear sealant & glue.

Adiseal is available in the following colours:

It can also be manufactured in any RAL colour.

Benefits of Adiseal Sealant & Adhesive

  • Works in dry, wet, even underwater
  • Good initial grab (for even more grab, use the other Adiseal colours or Adiseal Hi-Grab)
  • Gap filler adhesive
  • Resists mould
  • Over paintable (paint can be mixed into Adiseal Ultra Clear to make custom coloured sealant)
  • Non brittle (remains flexible)
  • UV resistant
  • Waterproof adhesive
  • Virtually odourless (no harsh solvent smell)
  • Isocyanate free
  • Solvent free (safe for use on sensitive materials)
  • No shrinkage or cracking (provides a better seal and bond)
  • Flexible adhesive
  • Prevent fungal growth
  • Prevent bacteria growth
  • Indoor and outdoor sealant and adhesive
  • Good resistance to chemicals
  • EC1 Plus certified (no VOC)
  • ISEGA certified – safe for use in food preparation areas
  • Suitable for internal & external use

The standard adhesive drying time for Adiseal is 24 – 48 hours to fully cure. Curing times can increase in colder temperatures.

How to seal underwater

Details of how to seal underwater.

  1. Clean and prepare the surface

    Ensure the area to be sealed is clean, free from debris to the best extent possible. Remove any loose or flaking materials.

  2. Apply the sealant

    Using a caulking gun or a suitable application method, apply the sealant directly onto the surface that needs to be sealed. Apply a continuous and even bead of sealant along the area.

  3. Smooth and shape the sealant

    Use a tool to smooth and shape the sealant. This helps to ensure proper adhesion and creates a neat finish.

  4. Allow for curing time

    Follow the manufacturer’s instructions regarding curing time. Keep in mind that underwater sealants may require longer curing periods compared to regular sealants due to the presence of water.

  5. Clean excess

    Remove any excess sealant.

Tip: To store Adiseal once opened, leave about 1cm worth of product out of the nozzle and store the tube upright in a cool dry place. Adiseal requires moisture for it to cure. The exposed part out of the nozzle will cure creating a cap. To re-use Adiseal, pull the cured part out or cut the nozzle until the uncured part is reached.

Wet Sealant

Adiseal excels in sealing, grabbing, and bonding in both dry, damp and wet conditions. To showcase its impressive wet sealant properties, a demonstration was conducted by pouring water on bricks. Adiseal was then applied on this wet surface, immediately grabbed and lifted with another brick. This test exemplifies Adiseal’s capabilities as a reliable wet weather sealant, among its other outstanding features.

Applying wet sealant on wet brick.
Applying wet sealant on wet brick.
Grab demonstration with brick
Instant grab demonstration of wet sealant on wet bricks.

Underwater glue

Adiseal is a versatile product that functions as both a sealant and adhesive. This makes it an excellent choice as an underwater glue. As demonstrated earlier, Adiseal has instant grab properties even in damp or wet conditions and it can cure underwater, providing a strong bond. In fact, in an independent test of adhesive strength, Adiseal outperformed its competitors by a significant margin. For further details, please refer to the Adiseal adhesive & sealant page.

How to glue underwater

  • When it comes to underwater gluing, a unique adhesive is necessary that can be applied, cured, and maintain a strong bond underwater.
  • To ensure optimal bonding, it is essential to thoroughly clean both surfaces. Remove any grease, dirt, or mould from the items that need to be glued underwater.
  • Apply the underwater glue onto one surface and firmly press the other item onto it.
  • The adhesive may take 24 to 48 hours to fully cure, so temporary supports may be needed to hold the items in place during this time.
  • Finally, remove any excess adhesive to achieve a clean and tidy finish.

Where to buy underwater sealant?

In the UK, you can buy underwater sealant at Adiseal stockists. For international customers, the sealant is available for purchase from online sellers such as www.guglue.com, who offer worldwide shipping. For more information on where to buy or to inquire about exclusive distribution opportunities in your country, please contact us.

Frequently asked questions about underwater sealant

What is the best underwater sealant?

Adiseal is the best underwater sealant. It works in dry, damp, wet and even underwater. It seals instantly, has the strongest mould resistance and colour retention underwater.

What product can be used as an underwater adhesive?

Adiseal can be used as an underwater adhesive. It works in the dry, damp, wet and even underwater. It remains waterproof and has an extremely strong adhesive strength bond.

How does an underwater sealant work?

Underwater sealants are formulated to cure and create a strong bond even in wet conditions. They often have special properties that allow them to adhere to surfaces underwater and resist the effects of water exposure.

Where can I use an underwater sealant?

Underwater sealants can be used in various applications, such as repairing leaks in swimming pools, sealing underwater pipes or fittings, fixing boat hulls, or securing underwater structures.

Are underwater sealants safe for aquatic life?

It’s essential to choose underwater sealants that are labeled as safe for aquatic life if you are working in an environment with marine organisms. Look for sealants that are specifically designed to be environmentally friendly and non-toxic to aquatic life.

Can underwater sealants be used for long-term underwater applications?

Yes, some underwater sealants are specifically formulated for long-term underwater use. These sealants have excellent durability and can maintain their bond and sealing properties even when continuously submerged.

What sealant can be used underwater?

Adiseal is a sealant that can be effectively used underwater due to its water-resistant properties, making it suitable for various underwater applications.

Suhail Matadar has extensive experience in the construction industry as an electrician, involved in installing, inspecting, and testing electrical systems in various projects. He excelled in sales, working for a major UK wholesaler, selling construction products to professionals and the DIY market. Suhail's background includes working at a leading home emergency repair company dealing with trades people. With a BEng (Hons) degree in Electronic Engineering, Suhail has worked with PLCs in the nuclear fuel manufacturing industry. During his studies, he gained practical experience at a chemical manufacturing company known for producing award-winning cleaning, hygiene, and livestock protection products for over a century. Currently, Suhail runs a global business specialising in supplying, researching, testing, and distributing chemical construction products like adhesives and sealants.