After we stripped the cloth off the reservoir and exhausters, we sanded them down so that they were nice and clean with no glue or material residue remaining
The bellows had been recovered in 1905 and the restorer had left a penciled note on the inside of the reservoir. The exhausters, however, were original. They were "harmonium style", that is, with large ribs with leather hinges and leather gussets. The conventional wisdom as that novices like us should not attempt to recreate these on the first go-around. We decided we would just recover the exhausters using bellows cloth (more on that, below).
We cleaned off the old ribs and sanded them down so that we could use them again in the exhausters. We then set them aside while we moved to work on the main reservoir.
We rehinged the bellows board to the movable reservoir board (for some reason I didn't take any photos of that) and then while waiting for the hinge to dry we cut the bellows cloth. When the hinge was dry, we used a dowel to prop open reservoir to its original 8" opening and then glued on the cloth using hot hide glue. This was our first time using hide glue. It think I applied a bit to much at first. It takes a while to get used to using it.
After it dried we collapsed it. All seems to hold together nicely. We temporarily sealed the valve holes and tested for leaks. It seemed pretty tight. Not bad for a first try.
Next, we carefully replaced the exhauster boards in their exact location and rehanged them. While waiting for the glue hinges to dry I decided to attempt the leather gasket where the bellows board joins to the foundation board. It was previously glued, nailed and screwed, with no gasket. We are not going to reglue it, but instead apply a gasket and then rescrew it.
I found a deerskin leather that I thought would make a good gasket. I temporarily taped it in place and affixed it with hot hide glue.
When it dried I used a scalpel exacto knife to cut out the airholes and screw-holes.
Next we moved on to the exhausters. When exhausters are recovered, usually the cloth that attaches to the bellows board is turned outward. These large exhausters were done the old-fashioned way. They also take up most of the surface of the bellows board and there is almost no room to turn the cloth out to glue it (either along the edges or between the exhausters) and certainly no room to apply a batten to hold it. I figured that perhaps it would be better to turn the cloth inward. I made a small paper pattern of what the exhausters would look like, with original ribs glued to the interior of the bellows cloth and cut it apart, and folded it, to see if our plan would work. It seemed to, so we proceed to do it with the real exhausters. We pencilled in where the cloth would turn under...
We carefully measured out the bellows cloth and pasted the ribs to the inside using hot hide glue...
We weighted them down and let them dry overnight. A few of the corners didn't quite take (I think this was an issue of learning how to use the glue and keep it at the right temperature), so we re-glued, applied more pressure, and "presto!"
And while we were waiting for the glue to dry we cut our valve leather to size.
... and attached them to the bellows board (exhauster interior)
When we were ready, we glued the cloth to the base of the exhauster...
I think it didn't turn out too badly for our first attempt, and for having to improvise on the exhausters.
We realized that we had a bit of leaking around the exhauster hinges. We figured this was the result of the cloth turned inward and not having enough of a tight seal around the bottom corners. We applied some extra bellows cloth around the bottom corners of the exhausters. I was not that happy about how it looked, but it certainly eliminated the leaking.
When we reattached the bellows system to the foundation board and reattached the side braces and springs we tested the vacuum. At first I was quite disappointed as we were only able to hold a vacuum for about 45 seconds. We wondered if it was the deer skin gasket. Remember, this is the piece of wood that we splintered and had to repair. I wasn't sure whether it was the deer skin leather, or whether our repair was uneven. I taped along each side of the join with masking tape to discern if that is where air was getting through. Sure enough, that sealed it up and we got just over two minutes of vacuum before the reservoir fully opened. I think that is fairly respectable. Rather than trying another gasket, or messing with the splintered end of the bellows board any further, I think we will just apply some bellows cloth along the seal where I used masking tape to test it. That way, if the bellows ever need to be removed, the cloth can simply be cut along the seal and when unscrewed, the whole system will come apart with no trouble at all.
We learned a lot doing this. There are several things I would likely do differently next time, but it was a very good learning experience.