Wessex System 4301 underwater epoxy: Mixing, coverage and application


Both Part A and Part B should be stored in a warm, dry environment where a temperature of between 10-30°C can be maintained.

To avoid skinning of the hardener component after use, replace the polythene film over the surface of the material.

Always keep containers closed when not in use to avoid contamination.

Usable life

Once mixed, the gel time of a 500g batch is approximately 50 minutes at a temperature of 20°C. Therefore, use immediately after mixing.

Surface preparation

Although Wessex System 4301 is tolerant of some contamination, best results are obtained on well prepared surfaces.

Ideally, surfaces should be abraded to provide the maximum mechanical key and be free from grease, moisture and dust particles. A solvent wash will remove any contamination.

If glass fibre laminate forms part of an underwater primary or otherwise important structure which is in contact with water such as a hull or dome, preparation should be confined to abrasion of the resin alone and the glass should not be exposed.

For emergency repairs when there is not time to prepare the surface, the effectiveness and durability of the bond may be impaired. Decisions regarding surface preparation must be taken on site dependent upon the individual situation. For advice, please contact us.


Mixing ratio: One part resin to one part hardener.

Before use, stir the epoxide resin and hardener separately to ensure complete dispersion of the colouring pigments. Then mix the yellow low viscosity epoxy resin component (Part A) with the blue hardener component (Part B). Blend thoroughly together. Mixing is complete when the adhesive turns green – but to ensure complete homogeneity we recommend a further two minutes mixing after the uniform colour is achieved.


When laminating with glass cloth this epoxy composition will cover approximately 2-3 square metres per kilogram, depending on the type and weight of the glass cloth.


Wessex System 4301 is primarily a laminating resin. When using glass fabric we would recommend the following wet method of application:

  1. Coat the substrate with the resin/hardener mixture at a rate of 3-4 square metres per kilogram.
  2. Work the glass cloth into the epoxy using a paddle roller or similar tool. Re-apply the epoxy to dry areas of the cloth and then roll another layer of fabric into the composite, wetting out any dry areas. Continue this laminating work until the desired thickness is achieved.
  3. When the desired thickness of the laminate has been constructed apply one protective coat of epoxy at the standard rate of 4-5 square metres per kilogram.
  4. Allow 6 hours at 18-20°C for the epoxy/glass composite to reach an initial cure – the epoxy will reach its full and maximum properties after 7 days.

NOTE: When laminating, if more than 16 hours at 18-20°C elapses between applications of the epoxy, then the surface should be lightly abraded, taking great care not to damage the glass fabric. The recommended method is to lightly abrade the surface using wire wool in conjunction with a household scouring cream. Wash and ensure the surface is clean and dry before applying further coats of epoxy.


All synthetic resin materials should be treated with caution. Contact with the Wessex underwater epoxy products may result in dermatitis if care is not taken to avoid skin contact with the resins, hardeners and mixed materials.

Always wear gloves when handling our epoxies, and as a further precaution, apply a suitable barrier cream to your hands if possible.

If any of the resin, hardener or mixed solution touches your skin, remove with a suitable cleansing cream, followed by thorough washing with soap and water.

Equipment care

Clean mixing equipment, tools and brushes with acetone or other ketones, or with a suitably blended solvent cleaner before the resin hardens. Once the resin has hardened, solvents are much less effective (please take suitable precautions when handling inflammable and volatile solvents).

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