Momentum Watch Flatline Chrono Black Luminous 42MM

Momentum Watch Flatline Chrono 42MM Black with Luminous Dial & Black Cloud Leather Strap

The Momentum Flatline Chrono 42mm Watch is built for adventure seekers who want a slim yet readable design. Our range of Momentum Watches all come with premium Sapphire Crystal making these adventure dive watches incredibly scratch-resistant. The Flatline Chrono is created to be a smaller and thinner watch, with a similar pilot design to Momentums' Titan III. Momentum Flatline Chrono is extremely thin at only 10.6mm in thickness. Incredibly thin yet this dive watch can still retain 100 meters (330 feet) water resistance because of its' screw-down crown. Momentum Watches are incredibly tough, rugged and good-looking sports watches ready for any outdoor ruggedness, whether it is surfing, diving, hiking, camping, fishing, boating or bushcrafting, these watches will survive the test of time.

Momentum Flatline Chrono Watch

 

Scratch-Resistant Sapphire Crystal

What is Sapphire Glass?
Synthetic sapphire combined of crystallised aluminium oxide

Astonishingly Sturdy
Value of 9 Mohs of mineral hardness same as titanium carbide

Scratch Resistant 
Superior to Quartz or gorilla glass

Application

• Watch Glass
• Display 
• Optics

Synthetic Sapphire: 
A synthetic sapphire crystal or “glass” is actually not glass at all. It is a very hard, transparent material made of crystallizing pure aluminum oxide at very high temperatures. Synthetic sapphire has the same hardness as natural sapphire gemstones, but without the colouring agents that give the gems their various hues. When it is heated, the synthetic sapphire forms round masses, that are then sliced into pieces with diamond-coated saws. These disks are then ground and polished into watch crystals. (One reason sapphire crystals are relatively expensive is that the tools required to cut and polish this extremely hard material are very costly.) Sapphire (whether natural or synthetic) is one of the hardest substances on earth. It measures 9 on the Mohs scale, which is a system for rating the relative hardness of various materials. (Diamond measures 10, the highest rating.) Watch crystals made of synthetic sapphire are often marketed as “scratch resistant” or “virtually scratchproof” because they are very difficult - but not impossible - to scratch. Diamond can scratch them; so can man-made materials that incorporate silicon carbide, which, with a Mohs rating of between 9 and 10, is harder than sapphire. So, if you accidentally scratch your watch on a simulated-stone surface or a wall that incorporates some of these silicon carbide materials, it could scratch the crystal.

AR Coatings:
Sapphire crystal is more reflective than mineral crystal due to its higher index of refraction. (1,8 compared to 1,47). Applying one or more layers of AR (anti-reflective) coating will limit this reflection to a very low level. Very often, lines and marks on the top surface of a sapphire crystal are mistaken for scratches but are actually the scratched AR coating, or just AR coating wearing off after time. An AR coating on the inside of the crystal provides a good AR performance while avoiding this problem. If you do scratch a sapphire crystal, then it cannot be polished away and will need to be replaced.
 
Waterproof gasket:
As both mineral and sapphire crystals are extremely hard, they have little or no “flex”. This means that when the crystal is inserted into a hard, steel or titanium watch case, it requires a gasket to ensure a waterproof seal.  These crystal gaskets are typically made of nylon, and are either flat, “I”-shaped or “L”-shaped. (see example above). The crystal is pressed into the case, using a crystal press tool. When it is pressed in, the nylon crystal gasket is “squeezed” between the crystal and the case rim, making a reliable waterproof seal. Over time, these crystal gaskets can become brittle and break, so it is a good idea to change the crystal gaskets every few years, to ensure the ongoing waterproof performance of your watch.