Glue-Creep Analysis Part 2: Taking Creep to the Next Level
It has been a little over 3 months since I published the first part of my Glue-Creep study for Gorilla Glue. In the first phase of this experiment, I looked at testing a variety of factors that may contribute to an exposed glue-line (such as a table-top) to creep above the surface of the wood. After testing a mix of environmental, mechanical and chemical factors in the first round of tesing, the results were inconclusive in replicating what a number of woodworkers experience (regardless of glue manufacturer):
“Moving forward, the current samples should be monitored on a monthly basis for a period of 8-12 months to expose them to a full cycle of seasonal changes. Subsequent tests could include testing a greater variation of grain orientation in the wood pieces that are glued together as well as sanding and finishing the samples before allowing a full 24 hours of cure time.”
Six wood species with seven glue lines and three finishes as well as the change in environment and time have had no additional impact in producing “glue creep”. As a result, I’ll be moving into the next round of testing in an attempt to hone in on what may drive this elusive phenomenon to occur, albeit inconsistently. All 7 adhesives used in the original test will be used again as a control.
- Gorilla Glue (Polyurethane)
- Gorilla Wood Glue (Type II PVA)
- Titebond I (PVA)
- Titebond II (PVA)
- Titebond III (PVA)
- Titebond Liquid Hide Glue
- Elmer’s Wood Max (PVA)
Additionally, this go around I’ll be testing some more extreme conditions and situations that may accelerate the process of glue-line creep such as:
- Clamping Pressure: testing some extremes of over/under-clamping.
- Grain Orientation: positioning flat-sawn to quarter-sawn pieces.
- Environmental Changes: forcing drastic changes in temperature and humidity over a short period of time.
- Clamping-to-Finish Duration: unclamping, sanding and finishing immediately after recommended clamp times versus allowing full manufacturer’s recommended cure time.
I’d be open to comments from anyone who has a particular experience in dealing with this when building furniture. What is your take on the factors that contributed to glue-line creep?
* Author’s note: I am contracted by Gorilla Glue to conduct this study as part of an ongoing effort to address customer service questions, but will not impact my methodologies or analysis of the results in future rounds of testing and commentary.