Apply a gelcoat of Epoxy.
This bulletin provides a brief overview as a step-by-step plan of how to apply an epoxy gel coat.
1. Ensure that the temperature of the Epoxy resin, substrate temperature and ambient temperature are within the same suitable range, usually between 18 – 23 °C.
2. Check that all components of the resin materials are ready for use.
Check for crystallization (solid material) or sedimentation / separation of the fillers. Crystallized material must be heated (40 – 60 °C) until all the material is liquid. Cool before use to 18 – 23 °C. Disposed / separated material (thick substance) must be thoroughly shaken before use.
3. Apply a release agent to the master / parent model. Processing instructions for the release agent stated in the technical data sheet (TDS).
4. Mix the epoxy and hardener components B according to the mixing ratio of the gelcoat as stated on the TDS information sheets. Ensure thorough mixing (including the sides and bottom of the mixing bowl) until both components are completely mixed. Avoid introducing excessive amounts of air during mixing. Use good meg tools.
5. Apply the mixed gel coat to the master with a brush. Use a good quality brush with a stiff brush. Layer thickness must be about 0.5 mm thick. A uniform layer must be applied so that all parts of the master are covered with the epoxy gel coat.
6. Let the coat gelcoat cure until it is at the stage where, when a finger is pulled slightly over the surface, no material sticks to it, but if it is firmly pressed, a marking of for example your glove will remain on the surface. We call this a B stage. How long this takes is influenced by the temperature, but is usually about 2 hours. This step is very important and requires accuracy. If the next layer is applied too early, the surface of the tool may be uneven. If the next layer is applied too late, poor adhesion between the layers is possible and very likely.
7. Repeat step 5 and 6 until sufficient gelcoat has been applied. A minimum of 2 x 0.5 mm thick layers is recommended and the total thickness of the gelcoat should be less than 2.5 mm. Make sure that the time between the layers is correct (see step 6).
8. Let the last coat gelcoat harden for the correct period of time (see step 6). It is important that the timing of this phase is correct. If the next layer is applied too early, the surface of the tool may be uneven. If the next layer is applied too late, poor adhesion between the layers is likely.
9. Apply the laminating resin or laminating paste. Processing instructions can be found on the relevant TDS information sheet.
10. Allow the finished tool to cure completely.
11. If necessary, after curing the tool, according to the curing schedule on the TDS information sheet.