Tie Browning

Very interesting thread. I enjoyed reading it. Too bad some of these members are no longer here. Major asset to Autopia as well as the Detailing industry.
 
Tire Browning

I have read many posts about browning seen on tires. It is supposedly an expected event as a tire ages and some tires are worse than others depending on the compounds in the casing. I was wondering whether how a tire dressing affects it or is some of the browning.

For example, after you dress a tire, the dressing erodes away over time so obviously so something is left on the tire over time after the optical (a dressed tire) effect is essentially gone. So, is some of the "brown" on the tire just residue tire dressing?
 
My understanding is that the browning is not so much a function of age but of use, as the antiozonant works its way to the surface, turning brown by exposure to the air. Thus Mike Phillips:

The science behind the modern rubber formulas used by major tire manufactures today is both complex and interesting. The rubber itself contains and ingredient called Antiozonant.

Antiozonant is an ingredient that helps to prevent the exterior rubber surface from cracking, checking, oxidizing, and deteriorating. The rubber is designed in such a way as to constantly work its way to the outside of the tire and as such, continually replenish the exterior surface with fresh antiozonant.

After the antiozonant works its way to the outside of the tire and is exposed to the ozone in the air, it turns brown. The technical term for this effect is blooming.

This is why you see a brown film on the surface your tires. You can wash your tires with soap or an all-purpose cleaner and remove this film, but in a few weeks, it's back. That's because the antiozonant continually works its way to the outside of the tires every time you drive your car.

Thus before applying a dressing you really need to do a thorough job of cleaning the outer surface of the tire to remove any spent antiozonants as well as any previously applied dressing and this will prepare the rubber to accept a fresh application of tire dressing.
Click to expand...

I have wondered tire dressing affects the blooming. My tires seem to remain black long after the dressing gloss has disappeared. Does it delay it? Does it hide it? Does it temporarily prevent the antiozanant that has come to the surface from turning brown?
 
The cause of tyres turning 'brown' is due to blooming (see (c) below) not excess tire dressing

Tyre Protection

Something that Mr. Goodyear discovered by accident, greatly improves wear resistance, and coincidentally, wet traction, it does not make the rubber harder or softer. The polymerization of butyl rubber changes its wear rate and traction, carbon black is the most important feature in traction.
If you were to see rubber going into a tyre factory, it would be grey, not black. Untreated tyres would have a very short life if they weren't protected against the elements and the environment, so amongst other ingredients, Carbon Black is added during the manufacturing process.

a) Carbon Black- protects the tyre against ultra violet radiation (UVR) by absorbing them and converting them into heat so it can be diffused safely. But the Carbon Black has a limited life-span because, as it does its job, it diminishes itself. When it is no longer there to protect the tyre, the original grey rubber colour starts to reappear.
b) Antiozonants- along with carbon black, the tyre manufacturer mixes in antiozonant and other protective ingredients to repel ozone from the rubber. These waxes and polymers migrate through the tyre at a molecular level to form a barrier against harmful ozone. As the tyres move (with the car being driven) the rubber flexes and heats up, allowing tiny amounts of the wax to surface. When a vehicle is not being driven (i.e. classic show cars, winter storage, etc) then without this action and the rubber can easily dry out and rot.
c) Blooming - after the antiozonant works its way to the outside of the tyre and is exposed to the ozone in the air, it oxidizes and turns brown. The technical term for this effect is blooming. Many chemical compounds, especially solvents, react vigorously at ambient temperatures as the oxidizing process takes place between water and the tyre polymer-binding agents. Water tends to wash away the natural oils and micro-waxes that help to maintain the tyres flexibility
d) Solvents - Michelin, Bridgestone, Firestone and most other tyre companies advise against the use of Dimethal solvent tyre dressings because they leach the rubber additives to the tyre surface, which then removes the elasticity from vinyl, rubber and paint; causing them to evaporate out of the substrate and could result in premature drying and cracking, leaving behind a dry inflexible surface.
e) Tyre Cleaners - for any type of protection to work efficiently on rubber it must be able to adhere to the surface. First remove any brake dust, blooming, road tar, grease and grime, wax and oxidized rubber from the surface to properly clean it. A tyre cleaner needs to be strong enough to tackle a heavy build-up of tyre dressings and road grime, but not damage wheel coatings.

It should clean the tyres down to the original rubber surface, this is especially important when you apply a new dressing, as dressings won't adhere to, or create the right shine on dirty rubber.

This tyre cleaner is a strong concentrate; spray-and-rinse tyres, without scrubbing, if you are starting on an old, neglected surface, use a fairly stiff tyre brush for the first application and a spray & rinse at least 3-4 times a year - PAC HiTemp Tyre Cleaner
 
Thus before applying a dressing you really need to do a thorough job of cleaning the outer surface of the tire to remove any spent antiozonants as well as any previously applied dressing and this will prepare the rubber to accept a fresh application of tire dressing.

Sometimes this is almost impossible to accomplish without the use of harsh cleaners, strong brushes, and respirators.
 
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