MARINE SILICONE SEALANT

Aquarium-grade marine silicone designed for fish tanks and heavy-duty sealing, formulated without fungicides to protect aquatic life. This clear waterproof silicone sealant creates a durable, flexible, watertight bond that resists UV, weathering, and ageing. Suitable for marine applications and general sealing, it adheres to many non-porous surfaces and maintains performance across temperatures from -40°C to 100°C, making it a reliable choice for long-lasting waterproof results.

Front view of Bostik Perfect Seal Marine Silicone Sealant in a 280 ml cartridge, suitable for sealing underwater and marine areas. The cartridge displays a marine background with fish, the word “Marine” in blue, and icons for permanent sealing, high salt resistance, and watertight performance.
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Technical Data Sheet (437.55 KB)
Colours

Clear

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Sizes
90ml
280ml
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Features & benefits Downloads & resources How to use FAQs Related products

Features & benefits

Bostik Marine Silicone is a waterproof silicone sealant suitable for fish tanks and heavy duty marine work. The clear, one-part bostik marine silicone cures to form a permanently flexible, watertight bond. It offers strong adhesion to non-porous surfaces and maintains flexibility across a wide temperature range from -40°C to 100°C. The formulation is resistant to UV, weathering, ageing, and water exposure, while also providing chemical resistance against diluted acids, alkalis, and household detergents. Its non-sag consistency supports vertical application, and it contains no fungicides, making it suitable for aquarium construction.

Surface Compatibility

Bostik Marine waterproof silicone adheres to a wide range of non-porous materials including glass, ceramics, enamel, porcelain, coated wood, painted surfaces, stainless steel, aluminium, and selected plastics and rubbers. It also functions as an adhesive where an elastic, gap-filling bond is required.

Smart advantages 

Fish tank assembly

100% waterproof

Permanently flexible

Low shrinkage

Downloads & resources

Bostik DIY South Africa Seal - Marine Silicone Sealant Technical Data Sheet (437.55 KB)

Technical Data Sheet

Bostik DIY South Africa Seal - Marine Silicone Sealant Safety Data Sheet (85.5 KB)

Safety Data Sheet

How to use

Applications

Suitable for building and repairing fish tanks and aquariums, as well as heavy-duty marine sealing tasks. It also works as a general-purpose silicone sealant for waterproofing and weatherproofing in and around the home, including sealing joints, gaps, and connections in DIY projects.

Ensure surfaces are clean, dry and free of loose materials, dust, grease, rust and other contaminants. Use masking tape to get a clean, even sealant line and to eliminate cleaning difficulties on porous surfaces. Remove tape before sealant skins.

90ml Tube  

  • Remove the cap and pierce seal with reverse side of cap.
  • Cut the nozzle to desired bead size and screw onto tube.
  • Apply silicone at a slight angle in a continuous bead to the prepared joint.
  • After use, remove the nozzle, wipe clear and replace the cap firmly.

280ml Cartridge  

  • Cut the tip off the cartridge and screw on the nozzle.
  • Cut the tip of the nozzle at an angle to achieve the desired bead size.
  • Apply with a caulking gun in a continuous bead to the prepared joint.
  • Remove unwanted silicone immediately.
  • Smooth down after application within 3-5 min before skin formation occurs, by using a flat or rounded tool. Sealant dries to touch in approximately 45 minutes and reaches full cure after approximately 24 hours.

Limitations 

  • Not suitable for alkaline surfaces such as concrete, plaster, or marble, and may corrode certain metals including mild steel, copper, and zinc.
  • It cannot be painted over and should not be used where mould resistance is required, such as bathrooms.
  • Discolouration may occur on natural stone or when in contact with certain elastomers.
  • Not suitable for polyethylene, polypropylene, or Teflon, and should not be used on mirrors. Application below 10% humidity may affect curing performance.

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FAQs

Is Marine Silicone safe for aquariums?

Yes, it is suitable for aquariums. The formula does not contain fungicides, which could be harmful to fish, making it appropriate for fish tank construction once fully cured.

How long does Marine Silicone take to dry?

Marine silicone dries to touch in approximately 25 minutes and reaches full cure in about 24 hours (depending on conditions and thickness).

How do I store my silicone?

To maximize the shelf life of an opened silicone cartridge, we recommend that the nozzle be removed and a piece of plastic placed over the cartridge tip after which the nozzle must be screwed back on. A large screw inserted into the nozzle tip also helps to extend the life. Store in a cool environment.

How do I remove cured silicone?

Cured sealant must be removed mechanically with a sharp knife or chemically with Bostik Silicone Stripper. Always test on a small surface first.

Which sealant is the right one for my application?

Our Glue Guide can help you find the best adhesive for your application.

How to clean silicone sealant?

For best results, clean silicone sealant while it is still uncured using a solvent such as turpentine or paraffin and a clean cloth. Once cured, the sealant can only be removed mechanically, for example with a sharp knife, or with a dedicated silicone remover.

How to dissolve silicone sealant

Cured silicone sealant cannot simply be dissolved. It must be removed either mechanically or by using a specialised silicone stripper designed to break down the material.

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