Shop Tips » Working With Epoxy and Fiberglass
Pastry Bags for Epoxy Fillets
In stitch-and-glue boatbuilding. epoxy "fillets" are what hold everything together. Whether you are filling the seams on a Lapstitch™ hull or you are bonding bulkheads to the hull shell, you'll be dispensing epoxy thickened with wood flour. Getting the epoxy into the seams is one of those things that's easy to do but hard to do well. One of the ways to do it well is to use these inexpensive epoxy filleting bags. They're just the thing for dispensing an epoxy-and-wood flour mixture, with great neatness and precision. You can get in expensive epoxy filleting bags from us, or just use a one-gallon freezer bag.
Step 1: Select a clear plastic bag - You can use one-gallon freezer bags, but make sure they are heavy-duty and high-quality. If the seams split you'll have an ungodly mess on your hands. We carry nice sturdy bags made just for this purpose.
Step 2: Load the bag - Use a clean, empty mixing container to hold the bag as you transfer the thickened epoxy from the mixing cup into the bag. Roll up the open end of the bag and work the epoxy down into the corner. Snip off the tip with grungy shop scissors. Try a 1/8” (3mm) hole for filling lap joints, and maybe twice that for filleting.
Step 3: Filleting with the bag - Squeeze the contents onto the joint as if decorating a cake. Dispense the entire contents of the bag before you set about shaping your fillets with your filleting tools. The concentrated epoxy in the bag will generate a lot of heat, accelerating its cure. Once you've spread the epoxy out, the exothermic reaction will slow, giving you more working time.
Step 4: Shape the fillets
Before you begin filleting, run masking tape along both sides of all joints you are about to fillet. It will make clean-up a breeze. Once you have shaped the fillets, pull off the tape. It will take any remaining excess epoxy with it.