Why Old Lume Stops Glowing
Vintage watches from the 1960s to the 1990s mostly used paint containing tritium. It is a radioactive isotope with a half-life of about 12.3 years. The glow is very dim after about 25 years, and it is completely dead after 50 years. You can’t recharge old tritium. So, you must replace it if you want glow.
Why Patina Forms
The old paint mix included a radioactive material like tritium, a phosphor like zinc sulfide that glows when hit by radiation, and a binder. UV light from the sun, moisture getting into the case, and the slow burning of the radioactive material change the chemical structure of the paint over time. Thus, this causes the color to change from white to yellow, orange, or brown.
The Process of Re-Luming with Faux Patina
You can’t simply paint modern, bright white Super-LumiNova over the old crusty paint. That would look terrible. The goal is “color-matching” or creating “faux patina.” Only a watch restoration expert can get the job done. Don’t let a regular mall jeweler try this.
Step 1: Removing the Old Lume (The Risky Part)
This is the most dangerous step for the watch hands. The old luminous paint is usually as hard as rock and brittle. It is stuck inside the metal band of the watch hand. According to our expert watchmaker, Aiman Moner, it is important to physically scrape or chip the old paint out, which requires very fine, sharp tools under a microscope.
- The Risk: Watch hands are made of very thin, soft metal like brass or gold. It is very easy to bend or snap a hand while pushing out the old paint.
- Another Risk: One slip of the tool can scratch the polished metal finish of the hand frame. Once scratched, it is difficult to fix without replating the whole hand.
Moreover, if the watch has radium paint (mostly pre-1960s), this step is a health hazard and requires special safety equipment.
Step 2: Mixing the Custom Color
Modern luminous paint, like Super-LumiNova, comes as a bright white or greenish powder. If you use this straight, the hands will look brand new and won’t match the old, yellow markers on the dial. The watchmaker must dirty the new paint by adding colored pigments to the mix.
Aiman Moner recommends the use of very fine earth pigments, which are powders in colors like burnt umber, raw sienna, and yellow ochre, or sepia. An expert watchmaker mixes the modern glowing powder, the clear varnish binder, and specks of these brown/yellow pigments. In addition, it is trial and error.
Mix a small batch, paint a test surface, let it dry, and hold it next to the watch dial. Wet paint looks different than the dry paint, so the watchmaker must repeat this until the dry color matches the dial patina exactly, says Moner.
Step 3: Applying the New Paint
The application is delicate once the color is perfect. The watchmaker turns the hand upside down and uses an oiler, which is a tiny metal rod with a flat tip, to drop the liquid paint mixture onto the back of the hand. The paint flows to the edges of the metal frame.
Surface tension stops it from spilling over the front, and the paint dries suspended in the frame, which creates a smooth, flat surface on the front. Remember, it looks lumpy if the mix is too thick. On the other hand, it sags in the middle if the mix is too thin.
What You Gain and What You Lose
When you ask if you can re-lume without affecting the patina, you must be clear about what that means. You are destroying the patina on the hands. You are physically removing the original, 50-year-old paint from the hands and throwing it in the trash. Remember, it is gone forever.
The Glow Will be Different
The new hands will glow very brightly at first because an expert uses modern technology. The old dial markers won’t glow at all. Likewise, the difference is obvious under a UV light (backlight). Old, dead tritium usually does not reach much UV light. The new color-matched Super-LumiNova will glow very brightly under UV light, even if the daytime color looks old.
Impact on Value
A high-quality, color-matched re-lume is acceptable for most vintage watches. It makes the watch usable again. It looks much better than having cracked, black, or missing lume chunks in the hands. However, never touch the hands for extremely rare or valuable investment watches like a vintage Rolex Milsub or Paul Newman Daytona. Even ugly original hands are worth more than perfect-looking restored hands to top collectors.
Also Read: How Often Should You Service Your TAG Heuer Watch
What Should You Do? Final Words
Yes, you can re-lume watch hands to match existing patina. A skilled and experienced watchmaker uses pigments to color modern glowing paints so it looks old. The benefit is that the watch glows again, and the hands don’t look awkwardly new against an old dial.
In fact, it stops old, crumbly paint from falling into the movement. On the other hand, you destroy the original material on the hands. There is a high risk of bending or scratching the metal hands during removal. The glow won’t match the dead dial markers.
