Titanium dioxide has become the material of choice for self-cleaning windows, and hydrophilic
A relatively new product, self-cleaning glass has a coating that helps to break down organic material so that water can remove it as it sheets off the glass. This low-maintenance glass is “sprinkled” with metallic titanium dioxide atoms during the glass manufacturing process.
Hydrophilic Self Cleaning Glass
This is when the titanium dioxide coating on the glass reacts with UV light to generate electrons that break down organic dirt into tiny pieces which rainwater can wash away. An easy way to understand how this glass works is to think of a non-stick frying pan.
Natural surfaces like butterfly wings, fish scales and lotus leaves also exhibits self cleaning property. These coatings have wide variety of applications such as window glasses, cements, textile, paints etc. Self cleaning material surfaces fall under two categories, hydrophilic and hydrophobic.
The Pilkington Activ glass has a special nano-scale – extremely thin – coating of microcrystalline titanium oxide which reacts to daylight. This reaction breaks down filth on the glass, with no need for detergent. When water hits it, a hydrophilic effect is created, so water and dirt slide off. .
Carbon-based nanomaterials such as graphene, carbon nanotubes (CNTs), and their derivatives, nanodiamond and fullerenes, offer unique self-cleaning properties due to their low surface energy, high electrical conductivity, and high mechanical strength.
Many leading window cleaning products contain ammonia because it is widely considered the best surfactant that gets the job done without leaving streaks. For that reason, many householders and commercial cleaners demand glass cleaners containing ammonia, such as Windex®.
A good flow of water across the glass is beneficial. Pilkington Activ™ still gives better results than ordinary glass with low angle roof applications. We recommend a minimum angle of 10 degrees, but 30 degrees or more is ideal.
2 The Lotus Effect. The ability of the lotus leaf to stay clean even in muddy water has inspired the development of self-cleaning surfaces. The surface of the lotus leaf is also extremely hydrophobic, i.e. it cannot be wetted by water.
Using the Self-Clean Cycle Requires Precautions
Those same high temperatures that help your oven clean can produce smoke and fumes. “When you run the cycle, turn on a range hood if you have one and open some windows,” Collomb says. If you have an air purifier, running it at the same time may help as well.
Any slight abrasion on the pane could take the coating clean off, which means heavy marks like splashes of paint can be difficult to remove. An accidental bump from a pole or ladder can also mark the coating. Secondly, and most importantly, self-cleaning glass is not totally failsafe.
All of these windows are coated with a thin transparent layer of titanium dioxide. This coating acts to clean the window in two stages, using two distinct properties: photocatalysis and hydrophilicity.
Off the shelf alkaline and acidic detergents are often used in traditional cleaning processes. These detergents are proven in certain applications but in cases involving titanium dioxide, they often end up targeting the titanium dioxide. The targeting of TiO 2 works by dropping the pigment out of the solution.
It has a thickness of about 25mm. The action of sunlight on the titanium dioxide generates a species known as electrons and holes. These electrons and holes, along with a specific property of titanium dioxide migrate to the surface and start a process known as oxidation of any organic material which is present.
Answer: Depending on how well it has been applied and how well maintained, it should last from 3-10 years.
A simple test is to spray water at the surface and compare it with ordinary glass, see it sheet off the glass rather than form lots of rivulets.
The semi-aquatic lotus plant has the remarkable ability to remain clean even in its muddy environment. By staying clean, the leaves can maximize their use of sunlight to fuel the plant.
In chemistry and materials science, ultrahydrophobic (or superhydrophobic) surfaces are highly hydrophobic, i.e., extremely difficult to wet. The contact angles of a water droplet on an ultrahydrophobic material exceed 150°.
The self-cleaning fabrics work using the photocatalytic properties of titanium dioxide, compound used in many new nanotechnology solar cell applications. The fabric is coated with a thin layer of titanium dioxide particles that measure only 20 nanometers in diameter.
Cost – self-cleaning windows are around 15-20 per cent more expensive than standard glazing.
So how do these nanoparticles help to self-clean a window? In the glass industry, if a thin layer of titanium dioxide nanoparticles are coated onto a glass window, these particles can act like catalysts. When the particles interact with ultraviolet radiation or sunlight, they produce electrons.
Although it does not need direct sunlight to work effectively, it does need rain so is not recommended where an overhang shelters the glass. Note: The minimum recommended angle is 10 degrees from horizontal, so that rainwater can flush away loosened deposits.
The first thing to note about self-cleaning windows is that they're not, in fact, "simple pieces of glass." They have a very thin outer coating of titanium dioxide, a white, powdery titanium compound best known for giving that dazzling gleam to paint, toothpaste, and all kinds of other bright white things.
Dish Soap Solution
Believe it or not, one of the most common and effective window cleaning solutions that is used by professionals is a mixture of dish soap and water. Simply mix one gallon of water with two teaspoons of liquid dish soap, and you have a professional window cleaning solution.
Stay Away from Harsh Chemicals
Harsh chemicals, especially those containing bleach or chlorine, should be kept away from glass surfaces. These chemicals can damage window frames, seals, and surrounding materials.