Events Calendar
Adhesives and Clamping
Saturday 01 April 2006, 08:00am - 09:30am
Hits : 516
Gerry Jones' class today on Woodworking Glues, Clamps and Clamping reinforces the fact that learning continues no matter how much you think you know. Starting the class was a definition of terms such as "specific adhesion", cohesion, "shelf life", "pot life", "open time", "glue set time", and "glue cure time". We often hear several of these, but don't always know how they apply to the specific glue we are using at the moment. An interesting fact is that most glues have an open shelf life (life after they've been opened) of only a year depending on conditions. For that reason you need to limit the amount of glue you buy to what you expect to use. Buying larger quantities usually ends up being a waste.
Gerry covered characteristics of most of the glues commonly used by woodworkers today including hide glue, PVA (white and yellow) glues, polyurethane glues, resin glues (formaldehyde and resorcinol varieties), epoxies, cyanoacrylates, contact cements and hot melt glues. Each has it's appropriate application. Ted Baldwin noted that yellow and white glues are not recommended for food applications such as cutting boards because bacteria can become an issue in the glues. Resorcinol glues are a better choice in that instance.
Whether you need to fill gaps, minimize glue creep, extend working times, color the glue or have it disappear, be able to remove the glue later or minimize set and cure times you have a lot of choices and one glue probably won't work for all your woodworking needs.
Before you apply any glue though you need to dry fit your pieces with the clamps in place. Doing this confirms the fit before you have wet glue to deal with, reduces the open time requirement for your gluing application, can avoid work by planning for cleanup and squeeze-out and even save a good project from the firewood pile.
There were lots of other points covered as well such as - leave room in your joint for the clue as appropriate, clean oily woods with acetone immediately prior to gluing, work area relative humidity should optimally be 40% to 50%, moisture content of the wood should ideally be 6% to 8%, and clamping pressure just needs to hold the pieces in place not squeeze all the clue out.
Thanks Gerry for all your work in presenting this excellent information for new members and old alike.
Paul Proffitt - President
Gerry covered characteristics of most of the glues commonly used by woodworkers today including hide glue, PVA (white and yellow) glues, polyurethane glues, resin glues (formaldehyde and resorcinol varieties), epoxies, cyanoacrylates, contact cements and hot melt glues. Each has it's appropriate application. Ted Baldwin noted that yellow and white glues are not recommended for food applications such as cutting boards because bacteria can become an issue in the glues. Resorcinol glues are a better choice in that instance.
Whether you need to fill gaps, minimize glue creep, extend working times, color the glue or have it disappear, be able to remove the glue later or minimize set and cure times you have a lot of choices and one glue probably won't work for all your woodworking needs.
Before you apply any glue though you need to dry fit your pieces with the clamps in place. Doing this confirms the fit before you have wet glue to deal with, reduces the open time requirement for your gluing application, can avoid work by planning for cleanup and squeeze-out and even save a good project from the firewood pile.
There were lots of other points covered as well such as - leave room in your joint for the clue as appropriate, clean oily woods with acetone immediately prior to gluing, work area relative humidity should optimally be 40% to 50%, moisture content of the wood should ideally be 6% to 8%, and clamping pressure just needs to hold the pieces in place not squeeze all the clue out.
Thanks Gerry for all your work in presenting this excellent information for new members and old alike.
Paul Proffitt - President
Location Stone Mountain Power Tool Corporation / Kentec, Lilburn, GA