Emergency Underwater Repair Pack Wessex System 110 Mixing, application and surface preparation
Mixing method
The yellow epoxy resin component (Part A) is mixed with the blue hardener component (Part B) in the proportion of 1:1 by weight.
Equal weights of the resin and hardener are blended thoroughly together. The different coloured components provide a visual aid to complete mixing which is indicated when the adhesive forms a uniform green colour.
Small quantities of up to 500g can be mixed by hand, but for larger quantities the use of a mechanical mixer is strongly recommended. Those employing a planetary action have found it to be satisfactory.
To avoid 'skinning' of the hardener component after use, it is recommended that the polyethylene film is replaced in intimate contact with the surface of the material.
Note: keep containers closed when not in use to avoid contamination.
Usable life
When the resin and hardener is mixed, the gel time of a 500g batch of UW43HV epoxy is approximately 40 minutes at 20°C and should therefore be used immediately after mixing. At higher temperatures the gelation time is considerably shortened and, as a guide, a rise in temperature of 10°C will reduce the gel time by approximately 50%.
Surface preparation
Although UW43HV is tolerant of some contamination, best results are obtained on well prepared surfaces. Ideally, surfaces should be mechanically abraded to provide maximum mechanical key and surfaces should be free from grease, moisture and dust particles. These contaminants may be removed by a solvent wash. If glass fibre laminate forms part of an underwater primary or otherwise important structure, such as a hull or a dome, preparation should be confined to abrasion of the resin alone and the glass should not be exposed.
When the adhesive is used to make an emergency repair, it will not always be possible to make ideal surface preparations and, in some cases, the effectiveness and/or durability of the bond will be impaired. Decisions regarding surface preparation must be taken on site dependent upon the situation in hand, but advice can always be obtained from Wessex Resins and Adhesives Limited.
Application
- Apply freshly mixed adhesive and work thoroughly into both mating surfaces prior to making the joint. The adhesive may be applied in quite thick sections if gaps need to be filled.
- Spread as evenly as possible with the minimum entrapment of air.
- Hold bonded surfaces together by light clamping or suitably placed weights until set.
- Do not subject to heavy stress until cure is complete. Time for adequate cure is a function of ambient temperature and the nature of the job in hand.
