Wessex System 4601: Mixing, application and adhesive properties

Specifications

Mix ratio (resin to hardener by weight): 1:1

Mixed density at 20°C: 1.5 gcm-3

Mixed viscosity at 20°C: 152,000 mPas

Pot life of 500g mix at 20°C: 100 min

Pot life of 2kg mix at 20°C: 45 min

Lap shear (mild steel): 16.1 MPa

Tensile adhesion (mild steel): 42.2 MPa

Storage

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.

After use always ensure lids are replaced and tightly secured to avoid contamination.

Surface preparation

Although Wessex System 4601 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 wipe with a clean, lint free cloth 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

Mixing ratio: one part resin to one part hardener.

Mix the buff coloured epoxy resin component (Part A) with the black hardener component (Part B). Blend thoroughly together until all signs of streakiness have disappeared and the epoxy composition is a consistent colour.

Small quantities of up to 500g can be mixed by hand. For larger quantities we recommend you use a suitable mechanical mixer. A planetary action works well too, along with correctly set automated mix dispense equipment.

In general, a minimum mixing time of 5 minutes is required to ensure complete mixing and, if using a static mixer, the first 6 inches should be removed and discarded to ensure the correct ratio.

Application

1. Apply freshly mixed adhesive using a spatula, trowel, stiff brush or roller, and work thoroughly into both mating surfaces prior to making the joint.
2. Spread a thin, even coat, trapping as little air as possible. On average, 1 kg of adhesive will bond an area of approximately 0.4 m².
3. Care must be taken to ensure that both surfaces are 'wetted'. This can be determined by pressing the flat part of a spatula or trowel onto the applied adhesive and then drawing it away quickly. If the adhesive becomes detached from the applied surface then it must be reworked into the surface and retested. If 'wetting' cannot be satisfactorily achieved to the substrate, remove the adhesive and repeat the surface preparation process.
4. Hold the bonded surfaces together using a retention device capable of applying an even pressure of 0.26 bar ± 0.05 bar across the entire surface. Care must be taken to ensure that the holding pressure is applied well before the usable life (pot life) of the adhesive has expired.
5. Do not remove the holding device or stress the joint until the adhesive has been allowed to cure for a period of either 12 hours (minimum ambient temperature > 20°C), 16 hours (15-20°C) or 24 hours (7- 14°C).

Usable life

Once mixed, the gel time of a 500g batch is approximately 100 minutes at 20°C which allows ample working time for most purposes.

For larger quantities the gel time is shorter and, for example, a 2 kg batch of material will gel in approximately 45 minutes at 20°C and must be used immediately after mixing. Higher ambient temperatures will result in a shorter usable life – as a rough guide, a rise in ambient temperature of 10°C will reduce usable life by half.

Safety

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 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).