WoodSkills Issue 02 - Page 71

71

Gluing Up

A dry run is always a good idea before final glue up. But as it would only be repeating information, we’ll go straight to setting up and gluing up. Lay out the vacuum bag on a flat surface and place the plastic covered base board inside. Surround the edges of the base board with strips of wool breather fabric. You should have more breather fabric close at hand for when you place the former inside. The breather fabric will allow the pump to continue to pull the plastic bag down onto the piece without self-sealing against the edges of the board or former. Everything should be now ready for gluing up. It’s good to try and think ahead and have anything that you might need close at hand as you’ll need to move pretty quickly once the glue is on the layers.

Glue choice for any process seems to always be a point of debate amongst woodworkers, but for laminations I would certainly avoid the use of any PVA or “yellow” glues like Titebond. These glues work brilliantly for joinery but have a certain amount of cold creep (movement or stretching when dry) which can cause your laminations to spring back, delaminate or just fail altogether. Instead, a resin glue which has little or no creep is preferable. Powdered resins such as Cascamite, Urea Formaldehyde resin glues such as Prefere 4152 or, for very heavy duty items or items with more materials than wood being used, an epoxy resin such as West Systems can be considered.