Hot hide questions

Re: Hot hide questions

Dennis

Hide glue is an excellent adhesive, but it does require extra measures. I have been told by mentors, who worked in an older era before modern glues, about the glue rooms in furniture factories, where the men worked without shirts in sweltering heat, on work tables that were also heated. Finishing rooms were similar. Important note, older shops had many hands, my mentor always required someone to assist in gluing operations.

I don't make furniture, but In my own work, I use heater, hairdryer, and brooder bulbs. I glue-size any endgrain involved in a glue joint, this usually requires an additional couple of hours, to dry, and refit any joint sfter swelling. Otherwise you would be creating starved joints, as the capillary action sucks the glue deep into the pores, and away from the joint. An advantage to glue-sizing is the joint has been preswelled, so things usually go together smoothly.

There are methods of extending open time for glue, garlic, aspirin, and urea are the most common. I have never used them, I'm afraid of glue faillure from unknown variables. Old glue is another variable I don't gamble with, so with important joints I will make fresh glue, the protein links breakdown with prolonged heating, and age. As for large case work, I can't speak of the order necessary, but it is almost certain anything pre-war was assembled with animal glue.

Re: Hot hide questions

jesse cloud

Its my understanding that hot hide glue gels at around 95 degrees. Here in the desert summer my joints stay flexible for a good while, maybe 10 minutes or so. If I need to apply some persuasion later, a few passes with a heat gun or hair dryer loosens things up. HHG can be softened about 4 times with no loss of strength. In veneer work, I have often done it three times with good results.

I have read, but not tried, that the working time of HHG can be extended significantly by adding urea, one of the processes used to make "liquid hide glue."

In your cabinet example, I would first of all do a dry fit to insure that everything goes together square, and then follow the sequence you suggested. No need to put glue on the sliding dts other than at the front, to allow to movement toward the back.

And, as you often advise, try it first on scrap. Much depends on the glue you use (higher strength glue gels quicker) and your shop environment.

Re: Hot hide questions

Don Stephan

As you probably know, hot hide glue is a liquid at the usual glue pot temp of about 140 deg F. When it has cooled to a different temp, which I couldn't find on a quick Internet search, it gels, giving it "grab." It isn't fully hard until the moisture has left the glue, usually given as about 24 hours.

Gelling is what makes hot hide glue so useful. Brush a layer on both surfaces of a joint. If the layer is not too thin, the thickness of the glue layer helps hold heat so the glue hasn't gelled yet. Bring the two surfaces together under even firm hand pressure and rub the joint back and forth a few times, forcing excess glue out of the joint. This makes the glue line thinner, making it cool more rapidly to the temperature of the surrounding wood, which makes the glue reach its gel temperature and have surprising grab. As moisture leaves the glue it shrinks, pulling the joint tighter. Tabletops, shelves, and such always get clamped, but a rub joint may be strong enough for non critical joints like edge to edge joints in drawer bottoms.

Hide glue granules can be purchased in different gram strengths. My understanding is that 192 is recommended for most furniture work, and that higher gram strengths may make a stronger glue but may also have less working time.

A couple years ago I glued up a chest of similar size and number of sliding dovetail joints using hot hide glue. The top was attached to the sides with half blind dovetails, and the front and rear drawer blades and drawer partitions with sliding dovetails. The drawer runner front tenons were glued into mortises in the front drawer blades but the rear tenons were inserted dry into the rear drawer blades to allow for seasonal movement. For the same reason drawer runners were not glued to the chest sides. Can't remember if the chest bottom was a full length sliding dovetail or simple dado joint.

The first day I glued to top and bottom to the sides of the chest, the front drawer blades, the front drawer partitions, and the drawer runners. The rear drawer blades and partitions were dry fit. The second day they were glued.

Before any gluing, I made two complete dry runs to identify clamp needs and locations and develop some smoothness in the process.

Several years ago I noticed yellow glue was especially quick to "skin over" which I believed would contribute to poor glue joints if the skin was present. I have not had significant issues using hot hide glue and would not expect work in progress to have any more or less flexibility than if yellow glue was used. After just a few minutes I would expect the same approximate difficulty trying to disassemble a glued joint regardless of whether hot hide glue or yellow glue was used.

I am confident that the sliding half dovetails in your chest are going to be what I've heard called a friction fit - can be assembled with hand pressure but not without, - so there's not going to be excessive movement in the partially assembled chest regardless of the adhesive being used.

Liquid hide glue doesn't have the gel grab of hot, so it likely offers more time when a joint can be disassembled, but I haven't tried to confirm.

Re: Hot hide questions

Bruce, a MN Galoot

On Bill T's recommendation, I used liquid hide glue to assemble a 24" sliding dovetail. It slid together as if greased. I've tried sliding dovetails of only 8" with yellow glue and scarcely had enough time to get them together.

Re: Hot hide questions

Larry Clinton At Frankfort, (Central) Indiana

Bill, I have never used Hot hide glue for case construction, or panel assembly. I have no issue with using "different" glues on one project. As I stated earlier, I use hot hide glue on those parts that I feel may need repair due to usual stresses expected in normal use like chairs etc. I don't believe it would be possible to completely assemble and glue up the case you show in your picture at one time. I may be wrong but sure seems like an exercise in futility. I have used jigs to hold parts square in assemblies like that and did partial assemblies at a time even with Titebond. If my son is available, I might do the complete assembly as you do!

I am a firm believer in Hot hide glue for certain items and obviously know it can be used to glue up very complicated furniture as witness a lot of antique case work. However I imagine the craftsmen of the day had many tricks that have been forgotten, and today we have a lot of good options that don't require those tricks.

I don't believe the "old ways" were in most cases as good as today's methods. They worked with the constraints of the tools and materials they had available. Many of today's youth had no conception of the amount of man-hours went into the furniture of those days. Granted the hand made furniture was much nicer looking and far more durable than today' mass produced furniture, but most was beyond the budget of new homemakers ~ most of them used Grandmothers dining room set, and hand me down dressers, beds and most other items. Few were new purchases of furniture by the working man.

I remember in the late 40's and early 50's working with an older craftsman/carpenter named Ruben. I have seen him rip a 1X 8' long with a hand saw and it was cut true and square within a 1/32". However he later purchased one of the first Milwaukee electric saws I had ever seen, I never saw him using a hand saw for ripping again! I often wonder what he would do with the tools I have available in my shop. I would bet he would have an ear to ear grin.... I also am sure he would adopt the modern adhesives without any hesitation.