Home Forums General Discussion Forum Rust on the hands Reply To: Rust on the hands

Bob Tascione

    Hi Chaplin37,
    The following bluing method may at first glance seem complicated and time consuming but it’s really quite simple and fast.

    Bluing hands and steel parts serve two purposes. It offers some protection against rust and when done correctly looks great. On the other hand when done incorrectly it can ruin the ascetic continuity of a watch. If hands, screws and other parts are blued in a watch their colors should match. If they don’t it’s immediately noticeable. Any parts to be blued should be pre paired to the desired surface finish. The finish you see before bluing is the finish you will see after as bluing won’t cover up any imperfections, scratches, or pits caused by rust. It just makes the part blue. So preparation is key here. If hands have a small amount of surface rust it can be removed in many ways. Some people use rouge and other compounds and or oil with pieces of peg or pith wood. Others use super fine wet/ dry sand paper and then polish the fine scratches out. The more the hands are polished the deeper and richer the bluing will look. If the rust is deep enough to where it can’t be completely removed without distorting the hands then it’s best to try to find a new or at least better set to work with as the remnants of rust will show through and will look like a blemish at best. After preparing the surface it’s super important to do a thorough cleaning. I usually run the part through a watch cleaning machine. You can use isopropyl alcohol, acetone or other cleaners if you wish. As long as the hands are completely free of all dirt, oils and cleaning residue you’ll be fine.
    There are several ways to re-blue the hands. I’ll cover two of them here.
    One way that I haven’t had much luck with is cold bluing liquids that gunsmiths use. It’s a quick process but I just can’t seem to get the color I’m after. It’s probably just me because I’ve seen guns that gunsmiths have blued using this stuff and they turn out beautiful. I’ve even tried following the suggestion of a gunsmith friend which was to heat the hands and parts to about 150 degrees Fahrenheit before applying the liquid which supposedly opened up the pores to allow more penetration into the metal, still no luck. Always turned out looking too dark, too blue (bright blue) or too blotchy.

    The second process is what I consider the correct way when it comes to horology (of course that’s probably because I can’t figure out the cold bluing technique) and that’s heating the hands slowly and evenly while closely observing the metals color transitions as it passes through a range of increasing temperatures. The procedure I use is a well known, proven method that many watch and clock makers have used over the years. There are variations to it so you can always experiment with different ways to see what works best for you. Some people place the hands on a thick piece of brass or copper plate and then heat the plate with a small torch, stove flame or alcohol lamp. This is the method that Roger Smith (see his bluing videos…links below) uses when making hands for his beautiful hand made watches. It works very well with flat pieces where the entire surface makes contact with the heated plate. Roger Smiths watch hand designs appear to be level making contact along their entire length when placed on the plate. I found that it’s difficult to maintain an even shade of blue over an uneven piece of steel such as a hand that has one or more curves to the underside resulting in only partial contact with the plate. The parts of the hand that are making contact will heat quicker and be a little hotter than the section not in contact with the plate resulting in uneven color across the hand. Using a layer of very fine brass filings will remedy this problem. If the hands are placed onto the filings and then moved around while lightly pressing down, the filings will fill the uneven empty hollows making contact with the entire surface of the hand. This will distribute the heat evenly over the entire length and width of the hand. Some people use sand and other medium in place of brass filings with success. It’s important not to cover any of the top surface of the hand as you will need to watch the color changes as the brass plate and filings heat up and transfer heat to the hand. I find that I have better control over the heat by suspending the plate across two upright bricks and hold the flame under the plate heating it slowly rather than from the side or top. Also a thicker plate of a half inch or a little more isn’t as prone to abrupt temperature changes as a thin plate if the flame is suddenly moved closer without realizing it. Your comfort zone may be much different than mine. You may find the complete opposite true for you where using a thin bluing plate works better so experimenting with some spare hands or parts is recommended before tackling an important part.
    I personally have difficulty seeing the color changes under florescent lighting. Incandescent lighting is better but indirect sunlight by far works best for me so I usually do this type of work near a shop window.
    As the hand moves into the lower 400 degree Fahrenheit range you’ll notice it changing to a faint straw color. From this point on things happen very quickly. The hand will now run through the color spectrum from light straw color to light yellow, darker yellow, light brown, dark brown, through the purple colors, and into the blues (I’ll try to find a temperature color chart to put up here in the morning). These color changes all happen during a 150 degree temperature change with dark purple to blue taking place over about 10 degrees! The desired blue color will be reached very quickly once you hit the purples. The instant it hits my target color I grab the hand with a tweezers and drop it into a cup of water. If it takes more than a second or so to do this I’ll most likely miss my color. Another way is to dump the brass shavings and all into a large container filled with water. Again experimenting is a good idea to figure out what works best for you.

    Roger Smith Bluing Hands

    Hope this is helpful Chaplin37,