marcelo wrote:
So, if I understood:
1-Apply first coat. Let it dry.
2-Apply second coat. Let it dry.
3-Apply the glass on the hull,
No more than 24 hours between the steps, otherwise, more fairing!!!
Close.
It’s not a fairing issue but a secondary bonding issue. Regardless of which brand you use there are 3 stages to epoxy curing: (I’m taking this straight from west systems so don’t assume I’m a chemical engineer, ceramic engineer yes, chemical no)
1. Liquid-Open time: Open time (also working time or wet lay-up time) is the portion of the cure time, after mixing, that the resin/hardener mixture remains a liquid and is workable and suitable for application. All assembly and clamping should take place during the open time to assure a dependable bond.
2. Gel-Initial cure: The mixture passes into an initial cure phase (also called the green stage) when it begins to gel or "kick-off." The epoxy is no longer workable and will no longer feel tacky. During this do not disturb stage it progresses from a soft gel consistency to the firmness of hard rubber. You will be able to dent it with your thumbnail.
Because the mixture is only partially cured, a new application of epoxy will still chemically link with it, so the surface may still be bonded to or recoated without special preparation. However, this ability diminishes as the mixture approaches final cure.
3. Solid-Final cure: The epoxy mixture has cured to a solid state and can be dry sanded and shaped. You should not be able to dent it with your thumbnail. At this point the epoxy has reached about 90% of its ultimate strength, so clamps can be removed. It will continue to cure over the next several days at room temperature.
A new application of epoxy will no longer chemically link to it, so the surface of the epoxy must be properly prepared and sanded before recoating to achieve a good mechanical, secondary bond.
The fairing is done after all coats and glass are applied and a thickened mixture is used to level (fair) the surface to prepare for paint or finish coat.
I’m also building the lifting keel.
Got to go. Like you it’s going to be a busy day in the shop.
Greg