Wessex System 4303 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.

Please note: always keep containers closed when not in use to avoid contamination.

Surface preparation

Although Wessex System 4302 is tolerant of some contamination, best results are obtained on well prepared surfaces.

Ideally, surfaces should be mechanically 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.

Mix the yellow epoxy resin component (Part A) with the blue hardener component (Part B). Blend thoroughly together. Mixing is complete when the adhesive turns green.

Small quantities of up to 500g can be mixed by hand, but for larger quantities we recommend that you use a mechanical mixer. A planetary action works well.


  1. Apply freshly mixed adhesive and work thoroughly into both mating surfaces prior to making the joint. The adhesive may be applied thickly if gaps need to be filled.
  2. Spread evenly, trapping as little air as possible. Work thoroughly into both surfaces.
  3. Hold bonded surfaces together by lightly clamping, or suitably placing weights until set.
  4. Do not subject the substrate to heavy stress until final cure is complete. Time and adequate cure is a function of ambient temperature and the nature of the job in hand.

Usable life

Once mixed, the gel time of a 500g batch is approximately 40 minutes at a temperature of 20°C. Therefore, use immediately after mixing.


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, the hardeners and the 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 for handling inflammable and volatile solvents).

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