This blog is to show our customers the time and attention we put into developing the best products on the market. We know some people love the technical side of things so we thought why not let you in on some of our chemical knowledge!
- Water behaviour – The common misconceptions
Everyone loves beading and hydrophobic products. We certainly do! But why does it happen and how do they work? What do people mean when they say does it bead or sheet?
I saw a post on Facebook the other day asking for a recommendation for a product that would sheet instead of bead. I was astounded at the amount of answers from self proclaimed “experts” who were just wrong. They just added more and more misinformation on what the difference between beading and sheeting actually was so… here’s the actual difference:
We’ve all seen pictures of vehicles with crazy beading, but why does it bead? Well it’s actually down to a few factors:
- Adhesion and Cohesion – Adhesion is the tendency for dissimilar surfaces to cling to each other, for example glue has a massive adhesion which is why it sticks to most things. Cohesion is the opposite it is the tendency for similar surfaces to cling to each other, for example have you ever seen a water droplet merge with another? That’s because it has high cohesion with itself.
- Wettability – Wettability is the ability for a liquid to maintain contact with a solid surface. This is due to balance between the adhesion and cohesion of the liquid and the surface.
- Surface Tension – Due to cohesive forces a molecule of water in a droplet is pulled equally in every direction by neighbouring water molecules. The molecules at any surface being either the water-air or water-solid do not have the same forces acting on all sides and therefore are pulled inwards this is why droplets of water dripping from a tap for instance are spherical.
On a hydrophobic surface cohesion dominates over adhesion, that means the water prefers to be with itself than with the surface and forms droplets. Surface tension causes them to become almost spherical and the wettability is low as there is hardly any surface area of the droplet touching the surface.
That’s why you get beading!
On the other hand on a hydrophilic surface adhesion dominates over cohesion, that means the water prefers to be with the dissimilar surface than with itself and forms a film. Surface tension causes them to become almost flat and the wettability is high as there is a large amount of surface area of the droplet touching the surface.
That’s why you get sheeting!
The common misconception is that hydrophobic products cause sheeting. This is technically incorrect. What you see is sheeting but it is not caused by the hydrophobic product. This is where the misinformation comes from. The sheeting comes from the water on top of the hydrophobic surface.
When spraying a fine mist over a freshly waxed or sealed paintwork you can see incredible beads. That’s because the protection is hydrophobic and you can see as mentioned above the water hates the surface and tries to avoid touching it at as much as possible forming a bead.
However… if you then hose water onto the same paintwork you will see what appears to be sheeting. This is because the surface of the paintwork is hydrophobic but it is over saturated with water and although there is beading happening on a microscopic level at the surface the majority is suffocated. The first layer of water has suffocated the protection and instead any additional water is therefore only touching more water which stick to each other and form a now hydrophilic layer and appears to sheet.
So in the same adage of “guns don’t kill people, people kill people” – no, technically hydrophobic products don’t cause sheeting, the water they repel do.
- Detergents – What are they and why do we use them?
Detergent is a fancy way of saying soap. The proper definition is:
a water-soluble cleansing agent which combines with impurities and dirt to make them more soluble, and differs from soap in not forming a scum with the salts in hard water.
Detergents are made up of chemicals called Surfactants (Surface Active Agents), but like the soap you see in the supermarket there are many different types of surfactants; each designed to do a specific role. It’s our job to create a product blend of a little bit of everything so it can clean anything it comes up against. You’ll see these listed on the back of our products in line with EU regulation (EC) No 1272/2008.
Surfactants are usually very large molecules. They normally have a hydrophilic (loves water) “head” and a hydrophobic (hates water) “tail” making them look like a snake. These heads can differ giving way to 4 different types of surfactants.
- Cationic Surfactants
- Positively charged head
- Anionic Surfactants
- Negatively charged head
- Amphoteric/Zwitterionic Surfactants
- They have both positive and negative charges in the head
- The head is not charged (neutral)
Cationic Surfactants are usually primary, secondary or tertiary amines such as Benzalkonium Chloride. These contain chemicals called Quaternary Ammonium Compounds which are anti microbials and disinfectants which means they kill bacteria. Most disinfectants and hand soaps will contain cationic surfactants.
Anionic Surfactants usually have a specialised head such as a sulphonate or a phospate. If you look on a bottle of shower gel you’ll normally see the ingredient Sodium Laureth Ether Sulphate or SLES; the most commonly used anionic surfactant. They are very good foaming agents and used to create foam. Some snowfoams also use another anionic surfactants called Sodium Lauroyl Sarcosinate this is a fantastic foam booster and is what gives shaving cream it’s thickness.
Amphoteric Surfactants usually contain a head that has both a cationic amine AND a anionic group attached. Cocamidopropyl Betaine is an example of amphoteric surfactant that is included in many household products including most snowfoams as it is a cheap and renewable foaming agent. the Coco part of Cocamidopropyl Betaine comes from Coconuts! Cocamidopropyl Betaine is used as an emulsifing agent which means it helps things which normally don’t mix like water and oil mix, this is because it has both a positive and negative head.
Non-ionic Surfactants are the second most used surfactant around the world. They are commonly found in laundry detergents because their neutral heads prevent the formation of soap scum. Non-ionics are kinder on skin too as they are less toxic and produce less irritation.
Surfactants are very important when it comes to detailing. They do a number of special jobs and it’s why most of our products contain one or more types. For example our Equinox APC is great for cutting through grease and oils, the way it does that is by encapsulating the oily substances and allowing it to wash off with water which normally wouldn’t mix them. A surfactant we use in our Equinox is called Alpha Olefin Sulphonate. This is an Anionic surfactant. The negative hydrophilic head is attracted to the water and the long hydrophobic tails are attracted to the oil and the surfactant acts as a intermediate bridge to link the 2 together like below.
In school we learn there is 3 states of matter; gas, liquid and solid. In chemistry a colloid is a phase separated mixture which normally would not mix which is suspended within a medium. Unlike a normal mixture which has a solvent and a solute dissolved into it; a colloid is suspended and not mixed. The most commonly used one in detailing is an emulsion: a liquid in a liquid.
Many types of colloids exist.
- Liquid aerosol: a liquid in a gas e.g. deodorant/fog/hair spray.
- Solid aerosol: a solid in a gas e.g. smoke.
- Foam: a gas in a liquid e.g. whipped cream.
- Emulsion: a liquid in a liquid e.g. milk.
- Suspension: a solid in a liquid e.g. paint/mud/ink
- Solid foam: a gas in a solid e.g. polystyrene/pumice.
- Gel: a liquid in a solid e.g. jelly.
- Solid Sol is solid in a solid e.g. stained glass.
Fun fact: There are no know gas in a gas colloids!
Chemists use colloids to help make a number of products that require chemicals that don’t normally mix. In detailing we use surfactants to create emulsions for example we use a non-ionic surfactant in our Titan Tyre & Trim to make silicone oil mix with water. We also use thixotropic emulsifiers which not only emulsify but thicken as well. They work in the same way as surfactants but don’t have any cleaning power. They are better suited to making things like polish where we mix water, oil and wax.
- Cationic Surfactants
- Fallout Remover – The science behind the product
As with detailing lets start with everyone’s favourite smelling product – Fallout Remover! Now fallout remover is a bizarre mixture of chemicals, because they all do something different to aid with cleaning but all have to work together without interacting with each other.
The main purpose of fallout remover is to remove Iron deposits on your vehicle, be it the paintwork or the wheels. Now this may look complicated for some but below is how our product works.
The brake dust on your wheels is Ferric Oxide also known as Rust. It is made of Iron and Oxygen with the chemical formula Fe2O3.
The Iron in Ferric Oxide is reduced (which means it gains a negative electron) with Sodium Thioglycolate (the stinky stuff) in the presence of an alkali source to Ferrous Oxide (1) with the chemical formula FeO. The reduction turns the Fe3+ of Ferric Oxide into Fe2+of Ferrous Oxide.
The newly formed Ferrous Oxide then reacts with the Sodium Thioglycolate to form Ferrous Thioglycolate (2). The Ferrous Thioglycolate then immediately gets ionised into a Ferrothioglycolate ion which is dark red! The Sodium and Oxygen lost in the reaction then react to form Sodium Oxide which in the presence of water turns into Sodium Hydroxide (3) which keeps the reaction neutral; making it safe for use on paintwork. In the presence of water the Sodium Hydroxide dissociates into Hydroxide ions and Sodium ions. 2 Ferrothioglygolate ions then wrap themselves around the one of the Sodium ions in what is called chelation. This creates a heavier molecule (4) which gravity pulls away from your vehicles surfaces and gets removed when you rinse.
1. Fe2O3+ 2HSCH2COONa + 2e– → 2FeO + 2(SCH2COONa)– + H2O
2. FeO + 2(SCH2COONa)– → Fe(SCH2COONa)2 + O2- → Fe(SCH2COO)22- + Na2O
3. Na2O + H2O → 2NaOH ⇌ 2Na+ + 2OH–
4. 2Na+ + Fe(SCH2COO)22- → Fe(SCH2COO)2Na2