I started working w/ Hide glue last year to make a kneehole desk w/ lots of veneer/banding challenges, and here?s what I learned:
Hide glue can be very messy. I was infuriated at times when it was sticking to everything and my hands were all gooey. Yet I would use it again in a heartbeat. It?s great stuff!
While veneering the banding that edges the desk everywhere there were a number of times I awoke the next day and decided to redo a portion. This fact allowed me to create a project that turned out far better than it would have if I had used regular white/yellow glue. I cannot overestimate the importance of this quality for someone still learning the craft. When people talked about the reversibility of hide glue, I always understood it to be something that would be important for some future restorer of the piece. It took a while for me to come to the realization that the biggest user of the reversibility would be myself! It was like I had spent my entire woodworking life working with a typewriter where the only way to fix a mistake was to use whiteout. And then suddenly, someone sits me down behind a word processor and introduces me to the Undo key. WOW!!!!!
I bought a cheapo hot-pot at the drugstore - the types meant for college students. I paid about $10 for it. I turned it?s thermostat down and filled it with water and then measured the temperature. I noticed that at its lowest setting it was still too hot for hide glue. So I took it apart and bent the metal thermocouple a little, and presto - it now maintains a perfect 140 degree temperature at its lowest setting. I stick the glue in an old soup can, and immerse that in a water bath in the hot pot. This keeps the hot pot clean. It?s seen lots of use, and it?s still working well.
I used an old latex paint brush and one of those cheapie flux brushes. I suppose there are better brushes out there, but I found these old brushes to be perfectly adequate.
I used an old clothes iron for the hammer veneering. I found that the hide glue would always bleed through the end grain on the figured burl veneer I was using, no matter how much I sized it before hand. So I had to clean it after every use w/ a vinegar solution. That was a real yuch.
Robert Millard has an excellent DVD that not only gave me the courage to try hammer veneering, but more importantly, gave me the knowledge I needed to recover when things went wrong. Can?t say enough good things about it: http://www.americanfederalperiod.com/candlestand%20dvd.html
For the hammer veneering I tried using 192g and 315g strength glues, as well as mixtures of both. The woodworking catalogs claim that the lower gram strength stuff is better for veneering since it sets slower. I agree w/ Robert Millard, and found the opposite to be true. The higher gram strength seemed to tack faster, w/ I believe was helpful. But don?t put too much weight on this, the 192g strength works fine for everything, so I wouldn?t feel compelled to have lots of different grades on hand. I keep the 192g around as my ?general purpose? glue.
I used liquid hide glue while gluing up the case. It?s incredibly long open time allowed me to work in a calm and measured fashion, despite the fact I had scores of dovetails coming together for the first time. The thought of being rushed by glue seems like something I don?t worry about anymore.
When you buy liquid hide glue you have to make sure its very fresh. I made this mistake when I discovered a bottle I bought locally would not set. Now I buy a small bottle directly from Old Brown Glue just before I need it. The dry glue flakes have a very long shelf life btw.
I learned to really like the quick tack time of the hot hide glue ? it allowed me to really speed up the construction process. I literally squeaked with joy the first time I did a rub joint.
I believe it?s an old wives tail that scoring the veneer gives the glue a better bond. I tried it both ways, and could detect no difference in how the glue bonded. I do believe that a toothing plane is useful for evening out the surface of sawn veneer if you don?t have a thicknessing sander, and I also noticed that toothing the ground surface before applying the veneer kept the veneer from slipping about when you hammer it down. This could be very valuable under some circumstances. I did the whole desk project without toothing anything, so I don?t think it?s necessary.
One of the things that I struggled with was why the hammer veneering would work sometimes, and fail others. I came to realize that if I understood why the veneer stays put, I could perhaps gain some insight into this. Patrick Kennedy provided the hint in one of the Woodtreks video where he states the veneer is held down by the vacuum that?s formed when you press it down and the glue congeals. I realized that the veneer sheets that weren?t staying down were highly figured portions of burl that consisted mostly of end grain. I would try to clog up the pores by sizing the veneer before application, but this didn?t work. The glue in the pores would melt during the process of hammer veneering thereby releasing the vacuum and allowing the veneer to buckle. I learned that the best way to handle these ornery bits was to heat up a ?caul? made from foil lined MDF in the oven for a ? hour or so, and use it to clamp down the unruly veneer. I would lightly clamp the caul w/ a few fast acting clamps, nothing elaborate. If the surface to veneer was larger than my oven, I would make several smaller cauls and use them sort of like ?tiles? to fill up the space. I would remove the caul(s) after they cooled (about 45 minutes), and the veneer would always stay put at that point. This turned out to be so much faster and more reliable, that I started doing it for all the large portions of the desk. Towards the end, I was only using hammer veneering for the banding.
After finishing the desk I read a book by Charles Hayward on veneering that was written some decades ago. In the book he claims that most woodworkers who veneer with hide glue eventually learn to use a hot caul to press the large sheets of a veneer and reserve the hammer veneering for the banding. Funny, I came to exactly the same conclusion! When you read other references about using hot cauls, they make it sound difficult, or like it requires lots of specialized equipment. I?m not sure I understand what they are talking about?
Whew! I didn?t mean to write so much, but I think you touched a nerve. I was exactly at the same point as yourself 2 years ago, so I thought I?d pass on some of the stuff that I found most important.
Good luck, and don?t get discouraged if things go wrong at first. I have come to consider Hide glue one of the best things in my shop!
JB
