I haven't seen one of Mac's Musings in a while, so humbly offer up this installment of Kevin's Conundrums instead. I'm stumped. When glue is in the bottle, it doesn't dry. I presume because of the lack of significant contact with air. You smear it on a piece of wood and slap another piece on it, and presto, it dries. But there's no air there either! What's up w/that? Magic wood fairies or something?
...Kevin
Hello Kevin,
An interesting thought. I'm hardly an expert on glue; however, I've found that if glue is not spread thin enough between two pieces of wood, it may not dry well either. I suspect that the wood extracts the moisture from the thin coat of glue and allows it to set up.
Fred Holder
Hmmm - an interesting thought. I mostly use the Titebond equivalent of Gorilla Glue which is moisture activeated, but last night I was gluing up with good old Elmer's Wood Glue and it got me puzzling. Maybe it's not oxidation at all like I'd always assumed, but in fact good old literal drying...
...Kevin
Why do you think there's no air in a wood joint?
Take a chunk of wood. Weigh it then drop it in a bucket of water. After a time, pull it out and weigh it again.
May be a slight amount, but certainly much less than in the bottle! I think Fred is on to it with the wood absorbing the moisture...
...Kevin
Have you never had to clean out a glue bottle nozzle??? Glue does dry in a bottle.
Well sure, but as I noted there's a *little* air in the bottle. And when I've cleaned my nozzles they're usually pretty goopy, not a fully hardened mass. Maybe if they sat for 6 months...
...Kevin
Might be a temperature thing. LOL.. Down here in Houston, TX my nozzles gett prety stopped up with hardened glue. I typically have to pull the cap off and grab the glue with needle nose plyers.
Any way a sealed bottle contains and prevents the loss of moisture, I think loss of moisture is required for the glue to cure.
Don't get me started on the polyurethane glues, the humidity is enough to set that stuff up down here. ;~)
Finger Cots.
each of the various glues hardens by different means.
white/yellow glue by the extraction of moiture cyanoacrilate by the exclusion of air (and the introduction of certain catalyzing agents) poly glue by absorption of moisture epoxy by catalytic reaction Silicon adhesive - by absorption of moisture Hide glue by cooling. (same as hotmelt) the list goes on, some are catalyzed by UV, some by temperature,
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