To truly understand this phenomenon, we need to return to the essence of titanium anodization technology. The colors do not come from dyes; instead, they result from the interference effect of the surface oxide film on light - the thickness and structure of this film directly determine the color manifestation. It is precisely because of the characteristics of this film that the initial color is fragile.

The anodizing of titanium is a fascinating electrochemical magic show. Titanium is used as the anode, while other metals such as stainless steel are used as the cathode. With the help of specific electrolyte solutions, an electrochemical reaction is triggered on the surface of the titanium alloy, resulting in the formation of an oxide layer. This oxide layer has a significant effect on the reflection and refraction of light. Even more astonishingly, different thicknesses of the oxide layer will present completely different colors. Moreover, this oxide layer is protective in nature. It can serve as an ideal decorative layer, adding unique beauty to the items, and also as a wear-resistant layer, enhancing the durability of the items.
From a microscopic perspective, the oxide film itself is actually colorless. All the brilliant colors we see are the result of the "interference game" of light: when light enters the film, some of it is reflected at the surface, while the rest penetrates to the bottom and reflects back. The two beams of light meet and superimpose, some wavelengths are enhanced, some are cancelled out, and finally, the colorful patterns that our eyes perceive are formed. The thickness of the film determines the color - every single thickness corresponds to a unique visual wonder.

So, why does the color change when rubbing? The key lies in the fact that the sweat on our hands, the residual liquid on the wiping cloth, and even the water vapor in the air can slightly penetrate or adhere to the surface of the oxide film, altering its thickness. Even a very slight change in the film's thickness will disrupt the conditions for light interference, and the color that our eyes perceive will immediately change. It's like a beautiful painting; a slight disturbance from an external force can cause its colors to lose their original harmony and stability.
Wear gloves when operating
The most direct and commonly used method is to operate with gloves on. The gloves act as a protective barrier, separating our hands from the titanium anodized items. This prevents the substances such as sweat and oil on our hands from eroding the oxide film, thereby effectively preventing color changes caused by changes in the film thickness.

Therefore, whether for daily appreciation and handling, or for professional measurement and adjustment, developing the habit of wearing gloves is equivalent to donning an "invisible protective suit" for this magnificent work. It is the simplest and most reliable guarantee for maintaining the color's lasting stability.
Another method that is said to be feasible is to apply a sealing liquid to the surface. The sealing liquid can form a protective layer on the surface of the oxide film, further enhancing the stability and anti-interference ability of the oxide film. However, in the medical industry, due to extremely high requirements for the safety and hygiene of products, currently, the main method of protection is still to wear gloves and avoid bare-hand contact. Because the composition and usage effect of the sealing liquid may have certain uncertainties, which may have potential impacts on medical products, it is necessary to handle it with caution.
Although the color change after titanium anodizing is somewhat annoying, as long as we understand the principle and take appropriate protective measures, we can keep that brilliant color for a long time, allowing titanium anodized items to always exude their unique charm.