Newton 306 LeakSeal


Suitable for bonding Newton System 300 hydrophilic waterbars to concrete, plastics and steel.

Can be used as a detailing product for Newton 403 HydroBond and as a sealant for service protrusions through the structure.

To be applied with a standard mastic gun.


A high-quality, firm, fast-curing, swellable, single-component, polymeric adhesive sealant. The special composition makes the sealant start to swell when in contact with water (to about 200% of original size).

The sealant has high elasticity and high adherence, and it develops a strong adhesive tensile strength immediately after application. The first swelling is time delayed which allows Newton 306 LeakSeal to be applied to slightly damp surfaces.

Consult manufacturer's literature for relevant surface preparation.

Features and benefits:

  • Very high resistance to water pressure.
  • Delayed swelling - will not swell during the installation process or during the concrete cure.
  • Swells up to 200% its original size to quickly seal leaks at joints in the structure.
  • Resistant to the high alkalinity of concrete.
  • Maintains very high elasticity and tensile strength, even when swollen.
  • Age resistant, no embrittlement.
  • Suitable substrates include concrete, steel, plastics and rubber.
  • Has a service life that can be equal to the design life of the structure.

General information




Grey matte


Hydrophilic paste- single-component, polymeric adhesive sealant


Paste form


Coverage (per cartridge): 20 mm wide waterbar: 6.5–8.5 linear metres; 30 mm wide waterbar: 5.5 linear metres

Uniclass 2015

Pr_30_31_76_39 Hydrophilic sealantsPrimary


D40/565 Proprietary waterstops

E40/320 Hydrophilic waterstops

Product range

System 300 - Waterbars, Waterstops and Waterplugs

Specification data - Hydrophilic sealants Enhanced data

Product Reference

Newton 306 LeakSeal (SX306)

Specific gravity


Tack free time (hours at 23°C and 60% Relative Humidity (RH))

< 8.

Tensile strength (MPa)



Up to 11 x initial size.

Swelling capability

Up to 3.5 times initial size.

Watertightness (bar)


Installation temperature (°C)

5°C to 40°C.

Service temperature (°C)

-40°C to 100°C.


Newton 306 SwellMastic Swelling Adhesive Mastic

Newton 306 SwellMastic Swelling Adhesive Mastic

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