How long until yellow glue dries?

[Greg Guarino]

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.

[Swingman]

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 temperatures.

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

[Leon]

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.

[-MIKE-]

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.

[Greg Guarino]

I guess 11 hours is safe then.

Thanks. In this case I prefinished all of the parts (first masking the mating surfaces of the joints) before assembly, specifically to avoid adding squeeze-out to my glue-up anxiety list.

[Greg Guarino]

Thanks for the details. I always feel better when I understand a process a little bit, rather than simply following a procedure.

[Leon]

YES! LOL Generally the bond is good at 1 hour but instructions often indicate to not stress the joint for 12~24 hours.

[John Grossbohlin]

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.

John

[Keith Nuttle]

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 operation.

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.

[Martin Eastburn]