I have a good friend, Bob, who is a tireless entrepreneur and small business owner, with a day job besides. Happiest when busy, he has recently leased some maker space and is establishing a new workshop there. Soon Bob will need a workshop clock to help him compute the amount of time that has elapsed since he was expected home. I aim to satisfy that need with a new twist on the classic Tavern Clock.

First, some background on the clock. According to Martin Gatto’s wonderfully informative website, Tavernicus, Tavern Clocks are a distinct type of British wall clock that you may also know as Act of Parliament Clocks. They date back to 1715 and had evolved through several recognizable forms prior to their eventual extinction around the turn of the nineteenth century. Beautiful and bold, the defining feature of Tavern Clocks is their enormity, often having dial diameters measured in feet. These clocks were created to hang on the walls of Taverns and Inns to provide a reliable time reference for patrons waiting to catch a coach, or adjust their personal carriage clocks. As such, they needed to be accurate and easily read from a distance, both of these traits being enhanced by size. I was unaware of their existence prior to a recent London visit when I happened upon one at a Kensington clock shop that took my breath away. Encountering a Tavern Clock at eye level was like seeing a sauropod skeleton for the first time. Did these things actually exist?

I soon developed an urge to make one of these giants, especially the round-dialed, dark and gilded breed that roamed The Land of Hope and Glory, c. 1760-1780. However, I could not fathom an excuse for such folly. Then I scaled-down a classic American clock during a recent Project and it hit me that if I really cut down the size of one of these guys I could make it relevant today. It wouldn’t actually be a Tavern Clock, but perhaps a suitable twenty-first century heir.

Design

As mentioned, there were a few distinct styles of Tavern Clocks that served the changing tastes of Georgian times. Gorgeous all, these were essentially defined by the face shape, trunk shape and material and I invite you to consult Tavernicus for a better description, including their blog which lists a stimulating rundown of recently traded examples. Toward the end of their reign, the dark chinoiserie decorated cases were superseded by beautiful brown mahogany. One day I may make a mahogany version but I wanted to start out with that black “japanned” look. Also, I had been reading about methods to ebonize wood using iron and this clock case would give me the chance to try that technique, too.

First, I needed to see more examples of Taverns so that I could settle on a design. The intention was to get a feel for the form and then cop features from a few nice ones to create my “own” version. When trying to virtually inspect furniture or clocks I have found that auction websites are the best. Auction houses need to show-off the inside and outside of their lots, and so one can gain a wealth of useful anatomical information from the various poses on display there. For run-of-the-mill clocks in particular, eBay is a boundless fount. A workshop clock need not be gussy and so the main features of my design were taken from the two simple examples shown below.

By the way, that brown clock on the right is over 7 feet tall! and lists for $15,300. Mine will be just over 2 feet tall and probably less valuable. Like the example on the left it will possess a round wooden dial with a similarly proportioned door. The trunk will sport a decorative element along the side, similar to that featured on the right hand example. The bottom will be closed up as in these examples, but lacking the trim line. Even without a firm idea on how to treat the edge of the circular face, a rough plan could be drawn that allowed construction to start.

Materials

I chose red oak for the clock case as this wood is loaded with tannins reported to behave well during the ebonization process. A couple of planks leftover from an earlier Project were enlisted to the cause.

Quartz clock movements are the best for dusty workshops and I picked up one, along with the appropriate hands, from an online dealer, Klockit. I tried my best to match the distinctive Tavern dial design in stencil form (Roman numeral hours with Arabic minutes along the chapter ring) and found one of those on Etsy, of course.

Dimensioning

The familiar quartet of miter saw, jointer, table saw and thickness planer were used to rapidly convert the flat sawn oak boards into meaningful part stock. The clock face is comprised of three, 3/4 in. thick boards glued together. All other parts are 5/8 in. in depth and it is only the thicknesses that were fixed at this stage, the lengths, widths and joinery features would be established during the proceeding, high-value cuts.

One-by-one the raw parts were refined into clock case components. This involved shaping grooves, tongues and rabbets with a dado blade at the table saw, a bit of chamfering at the router table, and then cutting all parts to their final lengths at the miter saw.

Portions of the door frame and door were cut with the aid of a circle-cutting jig at the band saw. The round clock face was also cut there using the same, 6 inch radius setting. To house the works properly, a 3/16 in. deep cavity beneath the center hole was carved out using a hand held router.

Following some experimentation on scrap wood I came up with a suitable edge profile for the face which was then carefully cut at the router table. I used a 1/2 in. radius cove bit to lighten the perimeter and then eased the backside with a round-over bit. Rotating the inverted face board along the bearing on top of the bit while also registering against the starting pin and a wooden stop made this an easy and safe procedure.

To complete the woodworking portion of this Project, I drilled a larger hole in the face for the clock shaft and then cut mortises into the door frame for the hinges. Assembly came next. The case was pretty easy to glue-up in the prone position and, once cured, a few dowels were added to further secure end grain joints. Finally, the wood was sanded to #150.

Finish

All that remained was to color the wood black, paint the dial in gold and then assemble the clock parts - coloring the wood being the most interesting step here. It is likely that black lacquer was used on the originals, applied lightly in many layers, to “coat” the piece and effectively smother the wood’s grain. I like wood grain, and so my goal was to color it black with retention of character. Paint was out of the question, and the typical petroleum-based stains would not blacken things enough. Modern dyes or even Japanese ink would likely work, but I was intrigued by results I had recently seen using iron to color wood black in a process called “ebonization”. This trick is intended to make common, tannin-rich woods such as oak look like their exotic cousin ebony (Diospyros ebenum). Let’s review the chemistry.

There are many references to ebonization in the woodworking literature, but the most thorough treatment I have found is a recent paper by Robert Q. Thompson in the Japan Wood Research Society’s Journal of Wood Science. In this work, a study of several common iron (II) and iron (III) salts revealed that the reaction of iron (II) acetate with wood tannins gave the darkest and truest black color. By comparison, commercially available iron salts possessing a chloride, sulfate or gluconate counter ion gave an undesired blue or green tint to the blackened wood. Certainly, acetate was the way to go and, fortunately, iron acetate is easily prepared in the kitchen by the reaction of steel wool as an iron source and white vinegar (aka acetic acid) as a source of both protons and acetate ions. Thompson even provides a simple recipe for this.

Add 170 mL of distilled white vinegar to 2 grams of #0000 steel wool in a glass jar; stir occasionally for 5 days and then pour through a coffee filter to remove any solid residue. (Important note: hydrogen gas is produced during the iron oxidation step so be sure to poke a hole in the top of the jar lid.)

When the resulting colorless solution is applied to a tannin containing wood, such as red oak, the iron (II) ions bind to the phenol groups lining the tannin structure (see below) and rapidly autoxidize to form iron (III). These iron (III) acetate-tannin complexes absorb almost all visible light, giving a deep black color as a result. Thompson shows that this all occurs within the first 60-80 microns of the wood surface (human hair width). But that’s enough!

Still with me? Here’s how things went in the workshop. With the clock face and door removed, all case parts were coated with the homemade iron (II) acetate solution using a foam brush. I applied a good amount of liquid with each stoke but not enough to leave puddles. Within a minute the wood goes gray and then continues to darken so that after 45 minutes it is a uniform black color - truly remarkable. I let things proceed until thoroughly dry (3 hrs) and then, following a light sanding, applied another coat as before. This made the wood a darker black color and I decided to stop the process there. How easy is that!

The grain of red oak has many fine crevices that are difficult to darken by this process, presumably due to surface tension effects of the aqueous solution. To catch these I first treated all parts with a wood sealer (Seal-A-Cell) followed by a light glaze using a dark brown gel stain (Java). Now uniformly colored but with the grain still on display, I then applied two coats of a satin wiping varnish (Arm-R-Seal) to seal it all up. Black is beautiful!

Next, I used the stencil and gold spray paint to create the dial pattern on the face. I also painted the hands a golden color. Not gold leaf, but still striking.

To complete the project I fixed a small brass knob to the door front, reinstalled the hinges and then mounted the door back into the mortised case. On the original, this door provided access to the pendulum and weights, but on my version it merely conceals a storage compartment. Next, the quartz movement and hands were a cinch to attach to the dial front. Bob will need to get at the backside of the works to set the time and replace the battery, and so I decided to mount the round face to the top of the case with a hinge for easy access.

And that completes the 21st century “Tavern Clock”. This scaled-down version serves as a workaday wall clock today, and also a reminder of magnificent timepieces past.

Best wishes, Bob. Enjoy every minute!