“Spray-on liquid glass” sounds like a product you’d see advertised at two o’clock in the morning in an infomercial.
It sounds even more like a 2 a.m. infomercial product when you see headlines about it that claim it is “about to revolutionize everything.”
Maybe it’d sound more impressive if I used its more formal name, which is “SiO2 ultra-thin layering,” but that’s hard to type, so I’m going to stick with “spray-on liquid glass.”
Besides, that’s exactly what it is: an extremely thin layer of glass that can be sprayed onto…well, just about anything.
Though it was invented in Turkey, the patent for spray-on liquid glass is held by the German company Nanopool.
It consists of almost pure silicon dioxide, a.k.a. silica, extracted from quartz sand. Water or ethanol is added, depending on what kind of surface is to be coated: the water-based versions are good for absorbent surfaces such as stone, wood and fabrics, while the ethanol-based versions are suitable for metal, glass, plastic and painted surfaces. There are no other additives: a bottle of liquid glass contains only water or ethanol, and molecules of silica. And not too surprisingly (since silica is the most abundant mineral in the Earth’s crust), the coating is non-toxic and environmentally harmless.
The glass binds to the surface through quantum forces that come into play at the extremely small scale of these tiny glass particles. The coating is only about 100 nanometers thick–that’s only 1/500th the width of a human hair.
An article in the June, 2009, issue of the U.K. magazine Cleanroom Technology has a pretty complete list of the coating’s benefits.
First of all, it’s flexible, meaning it can be used to coat, not just hard surfaces like countertops and sinks, but fabric, conveyor belts, medical devices such as endoscopes, and more.
It’s highly durable, able to withstand tens of thousands of cleaning cycles, and heat tolerant, unaffected by temperatures as low as -150 C and as high as 450 C. It also resists both acid and alkaline substances.
It doesn’t kill bacteria, but it also doesn’t provide them with a friendly surface to attach themselves to and multiply. Wash a coated surface with hot water, and the bacteria are wiped away more effectively than you can achieve with bleach on an uncoated surface (as tests in an Austrian cheese-packaging plant have proven).
It’s so thin that it’s invisible to the human eye and can’t be felt; while it’s slippery at the micro level, at the macro level (our level), it isn’t. In fact, since bacteria can be so easily cleaned off of it, a coated shower floor would probably be less slippery, because of the lack of bacteria-produced biofilms.
The stuff is easy to apply: even large areas such as floors, walls and windows can be coated with it in minutes, and no special equipment is needed. And finally (and even more amazingly), it’s cheap: the cost to cover a square metre ranges from about 40 cents to $1.80.
Sounds too good to be true, doesn’t it? Surely it must be full of little tiny glass particles that are going to get into our lungs and cause asbestos-fibre like problems?
Nope. The coating contains no discrete or potentially harmful engineered nanoparticles.
Spray-on liquid glass is already available in Germany for domestic use, for about $8.50 a bottle. In the home, it could conceivably make existing cleaning products obsolete, since hot water would do the job chemicals are doing now. It could be used in the oven, bathrooms, tiles, sinks, and on almost any other surface, and the coating is expected to last about a year with normal use.
Outside, the uses are endless. A silk shirt coated with it would shrug off a spilled glass of red wine. Stone coated with it could be more easily cleaned of graffiti. Seeds sprayed with it are protected from fungal and bacterial attacks and germinate and grow faster than untreated seeds. Wood treated with it has survived undamaged after being buried in a termite mound for nine months.
A Lancashire hospital has had “very promising” results using it as a coating for everything from equipment to medical implants, catheters, sutures and bandages.
It sounds amazing.
But it also still sounds like a 2 a.m. infomercial product.
I guess time will tell.