In case you haven’t noticed, I carry lots of titanium wire! But, I have had some of my customers ask “Why does my titanium wire have a light colored ‘fuzzy’ finish on the surface?”
When titanium wire is made it is drawn through a series of dies to reduce it to the desired gauge (wire diameter). The drawn wire usually has a medium to dark gray coloration and has a smooth surface. This dark finish is known as mill scale and is not very desirable for jewelry making. To remove the mill scale, the wire is etched in an acidic solution and then rinsed in distilled or deionized water to remove this finish and render the wire clean and scale free. Frequently this etching reveals the micro-crystalline structure and leaves the surface with a very light “whiteish” silver gray color and a slightly rough “fuzzy” appearance. This is sometimes mistaken for a titanium dioxide coating, but is just a result of the etching bath that the wire goes though and is not harmful.
Titanium dioxide is a naturally occurring mineral that is most commonly milled from ilmenite, rutile, and anatase. It can also be created by burning titanium metal. Titanium metal is coated with an clear, microscopic oxide layer that usually renders it inactive. However once titanium starts to burn in air it burns with a spectacular white flame to form titanium dioxide, TiO2 and titanium nitride, TiN. Titanium dioxide is used in many paints, coatings and plastics to enhance their color, vibrancy and opacity. It is also used in a wide variety of consumer products including some food products, sunscreen, and many other cosmetic preparations.
My titanium wire is surgical quality Grade 1, meaning it is more than 99.5% pure. The slightly fuzzy finish is actually proof of the cleaning process.
Our three finest gauges (32, 30, 28) receive a very light etch because a heavier etch would make the wire more prone to breakage. These three gauges have a somewhat shiny surface.
Our larger gauges (26 gauge and thicker) have a heavier oxide coating due to the heating and drawing process. They require a stronger etch which results in a matte finish and a slightly rough surface.
All the wire gets several rinses with deionized water to remove any remaining etch.