This is mostly a "curiosity" question. My schedule allows only brief
encounters with woodworking, so anything I glue up tends to stay clamped
well past the recommended time; several days, on average. But I'm
finally assembling the (prefinished) parts of the second pair of
bookcases and I noticed something this morning.
The shelves are in dadoes, and I've been assembling the bookcases face
down. I applied some shiny packing tape to the work surface under the
areas where glue might drip out. That kept the work from adhering to the
bench, but left some hardened glue in a couple of spots (on the first
two bookcases). That wasn't too much of a problem. I scraped it down
flush before I attached the face frames, and the areas were small.
I glued up another unit last night at about 8 p.m. I decided to have a
look at it this morning, at 7 a.m. I removed the clamps and had a look
underneath. Sure enough, there was squeeze-out, but it was a lot softer
than I would have imagined after 11 hours. Is this possibly because it
was relatively sealed in by the non-porous tape? Even some that had
collected in an exposed corner was pretty soft. The temperature in the
garage would likely have been in the low 60s.
Not unusual ... temperature plays a significant part in curing time. Read
the label, or find the manufacturer's data sheet online where they will
usually have the recommended working/clamping times at the various
With many woodworking glues I won't consider gluing a project when the
temperature is in the 50 degree range at all, and you were right on the
edge of that.
Check your glue specs and follow them
The thicker the clump the longer it tales to cure and temperature plays
a part. Glue clamp time is calculated assuming the thickness of the
glue in the joint is less than paper thin.
Add to that glue moisture is normally absorbed into the wood if it is
not being absorbed it will take much longer to cure.
Adding to what Karl and Leon already wrote...
The actual glue joints will be very strong at the manufacturers "set
time" which is generally around 30 minutes. I would speculate up to an
hour down around their minimum temperature for use.
Those glue drops and puddles will take days to harden, fully, and
sometimes never. If they "skin-over" fast enough, that skin acts like a
lid on the bottle keeping all air away from the glue inside the bubble.
It has been my practice to try to scrape away squeeze-out before it
hardens, but after it skins a little. There's a magic time for this that
is usually right around the set time for the glue. It's when the glue is
set enough (doughy) to be scraped without spreading further on the wood
and soaking into it, yet not so hard as to pull up any wood fibers or
have to be chipped off.
The window of opportunity for this only about 10 minutes, in my
experience. But when you get good at finding it, it removes a lot of
other work from the equation, including clean-up, scraping/sanding,
masking, taping, etc.
"Playing is not something I do at night, it's my function in life"
To try to answer your practical question which I assume is how long
should you wait for a glue joint to dry before continuing the next
I make a lot of picture frames and stretchers. They are miter joints
with biscuits. After the picture frames are assembled, I apply addition
wood to the frame to complete them. I usually allow at a very minimum
of 3 hours before I remove the clamps to complete the final wood work.
I prefer to glue in the morning and finish in the evening or over night.
If the next operation are going to stress the joints I would allow
additional time. Overnight should be more that enough for most
operations that will stress the joints. The more stress to the joint
the more time after gluing.
Regarding "dry," that seems to have two components to me. One is the
clamp/cured time for the glue and the other is the time for the surrounding
wood to normalize. As an example of the later, panels glued up using
biscuits or loose tenons can end up with depressions around the location of
the biscuit/tenon if they are sanded smooth too soon. This as the wood at
those locations was swollen from the moisture and hadn't normalized yet.
I guess the answer to your question is, it depends. It depends on whether
the glue joint is the only concern or whether the glue joint and wood
normalization are the concern.
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