Peter Rooke isn't new to restoring antique engines, but he's usually cleaning up parts, not making them look older.
For his restoration of 1917 Fuller & Johnson 1-1/2 HP engine, though, Peter had to make some new pieces look older to match the rest of the engine. Below he gives a brief explanation of how he used this same process on his 1916 1 HP International Harvester Mogul.
I have mentioned electrolysis in previous articles as a method to remove rust from metal parts. In theory, to generate rust it is simply a case of reversing the polarity of the electrolysis setup, connecting the positive power supply (anode) to the item and the negative (cathode) to the metal plate.
As before, I made the electrolyte by dissolving some washing soda in water, the ratio normally being around 5 percent soda (50 grams) to water (1 liter), and used an old battery charger as the power supply.
This worked well for the first parts, two short lengths of steel held back-to-back between two cathodes in the bucket. In this case a stronger solution of 10 percent soda was used. However, when it came to the larger part I found that the battery charger kept overheating, and this was due to a too-large current draw. After some experimenting, I diluted the electrolyte solution with water to 5 percent, and immersed only a bit of the large part in the electrolyte, keeping it as far away as possible from a single cathode. Another solution would have been to find a larger receptacle so the item and cathode would have been farther apart, or possibly the whole of the item could have been immersed if a resistor was used to reduce the amps drawn. This resistor could be a rheostat or even a light bulb, with experimentation needed to get the right balance.
In the smaller bucket the rust creation only seemed to occur in direct line of sight of the cathode. When I placed smaller parts in the same bucket, the rust appeared to be created all over, perhaps because the electrical forces were able to circulate more freely. Once the rust starts to build up on the item the current draw falls even farther.