What are 'ceramic' (or 'SiO2') coatings?

What is in a bottle of ceramic coating? What does 'SiO2' mean? What are graphene coatings? Why do some coatings last for years while others don't? Why do some products need applying professionally while others can be effortlessly applied at home as a spray, shampoo or snowfoam?

Our chemical experts are going to answer all these questions and more within this article in the typical Black Diamond fashion - Straight to the point and without the latest buzzwords or dishonest claims, because smarter consumers choose Black Diamond every time.

Ceramic coatings have become the gold standard in car paint protection, offering durability that traditional waxes simply can’t match. To any complete novices reading this who are wondering what these coatings are for, it's actually very simple - they provide non stick protective finishes on automotive exteriors, much like a wax. A ceramic coating provides a water and dirt repellent finish which protects paintwork from the elements, reduces the likelihood of scratches and keeps the vehicle cleaner for longer. Unlike a wax though they do not need regularly reapplying (or so they claim, with some products even promising several years). However, not all ceramic coatings are the same. In fact, there are two main types, and they work in slightly different ways. Almost all readers will probably be surprised to learn that despite common misconceptions and misleading marketing, neither type actually contains any SiO2 at all unless added for marketing purposes. 'SiO2' is actually the chemical formula for quartz which is sometimes used in car care for surface polishing as an abrasive powder or as a thickening agent but is virtually useless for surface coating. Here's a breakdown of the two coating types and the real chemistry behind them:

Type 1:

Polysilazane Based Coatings.

These are usually professionally applied and they use a special group of ingredients called polysilazanes - highly reactive materials which turn into a glass-like network when exposed to moisture.

What happens when you apply it?

• Polysilazanes are made up of chains with Si–NH–Si (silazane) bonds.

• When exposed to air and humidity, they react with water and oxygen to form Si–O–Si (siloxane) bonds.

• This reaction also gives off ammonia (NH₃) as a byproduct - you might notice a strong ammonia odour from the product or during application.

• The end result is a hard, microscopic shell made from silicone and oxygen atoms, similar to glass.

Cured Polysilazane

How is this useful?

• These Si–O–Si bonds are extremely stable - they resist UV, heat, cleaning chemicals and can even protect against mild abrasions.

• The resulting coating is therefore extremely hardwearing and typically lasts between 1 to 5 years depending on the specific formula and subsequent maintenance.

• The coating provides fantastic water beading and is extremely hydrophobic.

• Future washing and drying on coated vehicles is much faster and easier.

So what are the disadvantages?

• They need very clean, dry paint to bond properly - prep is essential.

• The polysilazane itself creates a rough feel to paint surface.

• Curing typically takes 12 hours or longer and may even require heat.

• The polysilazane itself is extremely sensitive to moisture which limits the types of products available. Polysilazane products must be solvent based and completely dry of water.

• The products are single use - once opened the product reacts with moisture in the air and the curing process begins even inside the bottle. This is why these types of professionally applied products almost always come in small single use bottles.

• They are hard to apply evenly and even harder to remove if applied too thick. They are usually applied by professionals and are generally not suitable for DIY or untrained users.

Type 2:

Siloxane Based Coatings And Other Sol-Gel Silanes

These are the more common of the two coating types and often found in shampoos, snowfoams, polishes, sealants and spray on products. They’re designed for easy DIY use, and they typically use modified silicone resins (called aminosiloxanes) to provide impressive protection with minimal effort.

What happens when you apply it?

• The main ingredients are usually aminoalkoxy siloxanes — these are silicone molecules with reactive –OCH₃ (methoxy) groups and amino groups (–NH₂).

• When applied to the paint and exposed to air humidity, the methoxy groups react with water to form Si–OH (silanol) groups

• The amino groups chemically anchor the molecules to the surface and help catalyze this reaction, making it happen faster and more completely - even at room temperature.

• The result is a thin, flexible protective layer of crosslinked silicone (Si–O–Si bonds), which is effectively bonded to your paint.

What does that mean in practice?

Amino-Alkoxy Siloxanes: Quick And Easy High Gloss Hydrophobic Finish

• The result is a coherent film, like a resin, which anchors itself to the surface and repels water.

• It creates a durable barrier which makes cleaning much easier and resists weathering and cleaning chemicals, typically lasting 4-12 months depending on the specific product, the degree of paint prep and subsequent weather exposure.

• They give off much less ammonia odour in use.

• They typically provide a high gloss and a slick finish similar to a more traditional wax.

• These coatings are usually designed to self-level and have longer, more forgiving working times meaning they’re easy to apply evenly without streaks.

• Aminoalkoxy siloxanes are less sensitive to water than polysilazanes - they can be emulsified and formulated in to water based products such as detailers, rinse aids, snowfoams and shampoos.

• The resulting coating compliments any existing coating on the vehicle,

  including polysilazane - they are great for maintaining or 'topping up' polysilazane coatings.

• Ideal for home users or for regular use throughout the year.

What are graphene coatings?

So what is the difference between a ceramic coating and a 'graphene' coating? Graphene is a fairly recently discovered man made material which is made up of a single layer of carbon atoms which has many unique and useful properties. Graphene in its real, raw form is incredibly strong and hydrophobic. Therefore it is often added to sealant formulas which are then sold as graphene coatings. In truth these are just one of the coating types we've already covered but now with additional small graphene particles suspended in solution. However, it is common knowledge within the industry that in practice these suspended particles do little to nothing, as they are mostly removed during buffing and those that remain trapped in the cured coating are unable to coat the surface in any meaningful way. Our own in house testing has never proven otherwise. In our opinion therefore, graphene is typically used for marketing purposes only as many consumers believe coatings containing graphene must be a step up from the ceramic coatings we've already covered and are therefore willing to part with more money to get them. This is why we do not add it to any of our own Black Diamond branded products and are always completely upfront with our white label and rebranding customers, only adding it if we're still asked to after explaining.