How To: Scarf Joints; Part 2
Once the scarf is cut, sanded and dry fit in the previous step, the sheets can now be glued together. It is recommended to use a marine grade epoxy for this application.
Tools and materials:
Eye and skin protection, tape measure, pencil, straight edge, clamps, bench or flat surface, epoxy, wood flour, mixing sticks, mixing cups, brushes, gloves and wax paper.
1. Prepare your work surface- use a flat surface that can support the clamping and materials to be glued. I use a butcher-block type of hard surface that I can clamp to on either side of the sheets. place a sheet of wax paper under the area to be glued. This will prevent the squeeze out to adhere your sheets to the surface.
2. Align the joints dry. Make marks along the edge to use as alignment marks. Sand, plane or modify to get proper fit as required. Once satisfied, dry clamp to test the fit. You can see I am using weights to hold the sheet down to ensure it lays flat against the table.
3. Flip the top sheet, exposing the feathered edges. Align as shown in the photograph.
4. Prepare the epoxy. Mix according to manufacturers directions. Using the brush, paint the scarfed edges with epoxy liberally.
5. Add wood flour to your mix. The desired mix will have the consistency of creamy peanut butter. This is used to thicken the epoxy to fill gaps and keep the glue in the joint. I use "wood flour" out of my belt sander bag. this is fine enough and if using the same material, will match nicely.
6. Spread the thickened epoxy to both joints
7. Flip the top sheet, align and clamp. Use firm pressure in clamping, but do not squeeze all of the glue out of the joint! Allow to fully cure according to manufacturers directions. It helps to keep the leftover epoxy to ensure the mix cured fully. It should be rock hard in the mixing cup after the recommended cure time.