Wax-filled engravings can greatly enhance the look of clock components. Although this is not something that you use very often, it's quite a simple process, and it's very easy to do. This is not usually a skill that's practised or used by beginners, but at the same time, it is not an advanced skill to learn. Anyone can learn this technique.
For this tutorial, I will be showing wax-filling on a simple brass beat plate. This is not a finely engraved example, but rather a cheaply mass-produced one that is easily available for a few dollars.
The tools needed for wax-filling are simple and inexpensive. You will need:
- Alcohol Lamp
- Alcohol (Denatured/Ethanol/Methyl Hydrate)
- A burn-in knife (or an artist's trowel)
- Dial "wax"
- Various sanding and polishing sundries
Before we begin, a few additional notes:
Alcohol Lamp: These lamps are easily found from clock parts suppliers, and are equally easy to find on eBay. I have this one (above, which can sit at different angles) as well as 2 other antique ones (with flat bases). They will often have a wick-cap because the alcohol will evaporate fairly easily from the lamp. If you're not planning to use the lamp again, empty the alcohol back into your container, otherwise it will be gone by the next time you need the lamp again.
The reason for using alcohol in these lamps (rather than oil or kerosene) is that the alcohol will give a clean flame that will not leave ugly black soot or oil residue on the pieces you're heating. It also burns with a blue flame that produces a lot of heat, but nearly no visible light (so you can stare directly at what you're working on, without blinding your eyeballs).
Knife: No particular knife is essential. You can use no knife, and simply rub the dial wax onto the heated piece to be filled, but the advantage of using a thin, flexible knife is that you can "squeegee-off" a lot of the excess wax, which (as you will see later) is difficult to remove in the finishing stage. The particular knife that I use is a dollar store item, but art supply dealers, clock parts suppliers, and specialty woodworking supply houses also carry them.
Dial "wax": The dial wax is actually not a wax at all. It is a deeply coloured shellac or lacquer product, and it is sold in sticks. For the purposes of this tutorial I'll simply refer to the product as a wax. Depending where you buy it, it may be called by different names (shellac stick, lacquer sticks, dial wax, dial shellac, etc), but it will always appear as a shiny fragile black stick. Clock parts dealers carry these, but be aware that you can also find them cheaper from woodworking suppliers. The place where I bought mine (Lee Valley Tools) sells the shellac sticks in about a dozen different colours, including clear and amber colours, which could be used for case repairs. I have also seen some rare and unusual engraved clock dials that used red or blue as an accent. The sticks generally cost around 5$ each.
General Safety Note:
When working with fire, be sure to work safely. Do not overfill the lamp, make sure to work on a clean, safe work area, and as a general safety measure, know where the fire extinguisher, first aid, and other such items are in your home, should you need them.
With that out of the way, let's get started. You will want to make sure that your engraved item is clean. I would not advise to highly polish and scour it in this case. Simply wash it and make sure there are no traces of oils or dirt on it.
When filling the engravings, you have several techniques that you can use, and they will depend strongly on your preferences. In my case, I like to heat the knife, and melt a small blob of the wax onto the tip. To help the wax "grab" the metal better, I also gently heat the piece that is being filled (use not-marring pliers). The rest is just a series of back and forth actions, heating the piece, the spatula, trowelling, heating, etc.
Note: Do not overheat the knife or the piece being filled. If you overheat the piece, you will notice that the wax gets too liquid and it will start to flow out from the engravings. If this happens, simply remove it from the heat, wait for it to cool slightly, and redistribute the wax. You need to hit just the right balance. If the wax is too cool, it will stick everywhere like honey.
You want to make sure all the grooves of your design are filled, but you also want to try to keep as little wax on the rest of the surface as possible. If you can completely avoid large flat areas, DO SO. On a very small item like this, it was easier to just cover everything thinly. On a large item like a dial, you want to do just the numerals and divisions.
Once your filled piece has cooled (don't put it under cold water as this could crack the wax), you can start the finishing process.
This is the only difficult part of the whole process. The excess surface wax must be carefully sanded. It will not want to come off easily, but have patience with it. You can use a combination of whatever abrasives you like, including steel wool, wet-dry sand paper, wet-sanding, etc. Try to use a sanding block to get a nice flat surface, and avoid coarse grits that could deeply scratch your finish surface. You will want to avoid any kind of power tool or wire wheels, as these will tend to pull the wax out of the engravings, or overheat/melt the wax from friction.
Once all the excess wax is removed, you can go over the surface in one direction. In the case of this beat scale, a "side-to-side" direction along the length of the piece worked fine. If you're working on a longcase clock dial, however, you will want to build yourself a circular sanding pad/platform. More on that in the future (or you can search the web for others' setups/tutorials for this).
Finish with a brass polish to buff the surface of the metal and the wax.
And that's it! This entire process took me less than 10 minutes (start to finish). It actually took 10x longer to edit and write this post than to actually do the wax filling. If you are after a silvered surface instead, you would do it at this point (more on this in a future tutorial), and follow with a clear spray lacquer. This finished beat scale is being left "natural" to tarnish/patina. You will note that the black shows up nicely with the addition of a clear lacquer.