This common problem of Headlight discoloration and yellowing is a source of much attention from those who are victim of the problem and from those attempting to offer a solution to the problem. There are many Headlight Cleaners on the market, but do they work?
Summary of this Guide.
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This guide is written to help the consumer make a truly informed decision. We will discuss the various offerings available both on and off eBay and whether they are truly effective. Our company provides Automotive Exterior Restoration Services and has a wide variety of experience in this field. We will try to share this experience and the knowledge gained from that experience in this guide as it relates to Headlight Restoration/Cleaning. It should be noted that headlight cleaning and headlight lens restoration are terms used which are not always used accurately. So we will attempt to help you understand the true science pertaining to why this problem occurs and rely on common sense to give you the answers from there.
First let’s look at what the lenses are made or manufactured from. They are made from "Polycarbonate" which is a form of plastic. Polycarbonates are unique because of their optical clarity, impact resistance, and resistance to high temperatures. The headlight lenses are made through a process called "injection molding" into ready made molds that make up the shape of the particular lens being manufactured.
The significance of the material these lenses are made from is extremely important to someone trying to repair cloudiness, yellowing and other damage.
Since these lenses are made from Polycarbonate plastic can they be "cleaned"?
One definition of cleaning is; 1. "Free from dirt, stain, or impurities; unsoiled". So you have to ask yourself; are your headlight lenses dirty, stained or soiled? And a stain is 1. "a discoloration produced by foreign matter having penetrated"… So is the problem caused by a foreign matter having penetrated?
No. This damaged is a breakdown of the surface of the lens caused by U.V. light from the sun, the same U.V. light which gives one a sun burn and may lead to skin cancer and so on. The problem these lenses have is the outside surface or coating has NO U.V. protection, which is evident from the damage caused by U.V. Light which is on the surface and outside of the lens. This damage is similar to the damage seen on some cheap automotive clear coats that flake off and peel or turn a chalky color.
To illustrate; the clear coat on your vehicle consist of similar components to the headlight lens. It is an Acrylic Polyester Urethane Clear Coating. Acrylic is made up of thermoplastic resins; (Polycarbonate is a synthetic thermoplastic resin). Polyester refers to its properties as to cross-linking polymers of different synthetic units. Its chemical equivalent is very similar to Polycarbonates and react too many solvents similarly.
However, Acrylic Polyester Urethane Clear Coats have U.V. resistance built into the chemical formula and the formulation is far more resistant to weather, namely the Sun, solvents and other contaminants. This is evident in the finish of all vehicles since the problem of U.V damage is almost unheard of in the automotive clear coats used today. (The automotive industry is forced to manufacture a higher quality product for clear coat because a factory standard paint job is $4000-$5000, a paint job that only lasts 2-3 years would be unacceptable to consumers!)
To protect the headlight lenses with a true U.V protective coating is not a cost effective solution to automobile manufacturers. The wholesale cost of industry standard Clear Coats with a quality U.V protectant is around $250 a gallon plus the application method which would have to be added in the assembly line process, to apply the U.V. Coating
Therefore Polycarbonate Plastic lenses can be easily damaged by the Sun (U.V. Light) and any number of solvents such as those found in things like, Brake fluid, lacquer thinners or any solvent that is chemically "hot". While the polycarbonate formula used in your headlight lenses has a high melting point compared to many other formulas that make up synthetic solids and other plastic parts, it has a low melting point if introduced or exposed too many solvents.
Since you would need a chemically "hot" solvent to have any effect to the surface of any polycarbonate, it will react similar to wiping paint thinner over fresh paint. It will have a dissolving effect on the surface of the lens. The resulting mess is almost irreversible.
At the very least it will not result in the highly shiny and optically clear polycarbonate original design and will be extremely unsightly! So, essentially the lenses can not be "cleaned" according to the definition sighted above. However, they can be repaired.
One definition of repair is; "to renew or revitalize" and to "restore to sound condition".
The science we use to restore your headlight lenses is the same used in ‘renewing or revitalizing" the Acrylic Polyester Urethane Clear Coat made up of the same type of thermoplastic resins found in your headlight lenses.
Let’s examine what will truly renew or revitalize your lenses or restore them. The science behind restoring faded, oxidized Clear Coats is wet sanding and machine polishing. Light wet sanding removes any damage and other imperfections from the surface. Machine buffing restores the clarity and shine to the Clear Coat.
The main difference between the lenses and Clear Coat is the thickness. The Headlight lenses are much thicker than the Clear Coat. The thickness of the lens allows for a very aggressive yet very effective repair allowing for even the most severe damage to be repaired!
Proper restoration methods employ low heat, low friction applications during the repair; (wet sanding) which keeps the lens cool and lubricated.
Restoring optical clarity is as important as removing the damage in the first place. The damage which dims or defuses the light coming from the light bulb is one primary reason people seek to repair these lenses in the first place. So it is equally important for someone looking to repair their lenses to seek out a repair/restoration method that will return the optical clarity and shininess to as close to factory specifications as possible.
We will return to the science behind automotive clear coat application to illustrate another point. Clear Coats must be "sprayed" from a properly adjusted, quality spray gun by an experienced, well trained and skilled technician in order to have a quality result without runs, large amounts of "orange peel" and other surface imperfections. They are sprayed because this is the only effective method of transfer to the surface of this very transparent, very shiny material.
Yet, the best qualified, most skilled painters will always wet sand and machine polish their paint jobs when the job requires a highly reflective, super shiny and optically clear finish, because it is very effective.
So the most effective and scientifically sound approach to restoring optically clarity, high reflectivity and extreme shine is by means of machine polishing since the lenses are so similar to the Clear Coat on your lenses except for the lack of U.V. protectant.
Without machine polishing you will never produce the required speed to polish the lenses effectively. In fact, hand polishing usually has very short lived results because the polish being used is designed to be used with a high speed buffer or similar. An Automotive painter would not even attempt to polish by hand. Any polishing effect will be temporary because the clearing is caused by the liquid composition of the polish which creates the illusion of clearing. However, without high speed or machine polishing, it doesn’t actually polish!
Try this, wet the lenses with water and in many cases they will look much better while the water is on the lens… until they dry. In fact, some products, like tire dressing, baby oil, mineral oil etc, will have a temporary effect of improving some of the appearance of these damaged lenses.
This will always be temporary, with only slight improvement without even coming close to achieving the original appearance from the manufacturer not too mention the mess tire dressings and other oils make and the dirt and debris that will stick to the lens.
Many of the materials needed to repair the lenses to like new appearance can be found in some auto parts stores and automotive paint supply stores. The trick is finding everything you need and knowing how to match those products with the corresponding product to achieve your goal.
The employee’s in those stores do not work in the reconditioning field and lack real world, working knowledge of how different products work and work with one another, most of the time they are just salesman, much the same as those offering headlight cleaners or polishes etc.
It should be noted at this time that just like the clear coat on your car which need wax or paint sealer to protect it from the elements, a quality paint sealer will go a long way to protecting your headlights after they have been restored. In fact a regular routine will protect lenses that aren’t faded or yellowed from becoming faded or yellowed. Remember, they are essentially the same thing as the clear coat on your vehicle.
We have put together a kit that uses this scientific approach with a professionally written guide to take you through the step by step process to achieve the best results possible.
The leveler and buff pad in our kit are matched specifically to work hand in hand with one another. This kit was invented from offering this service and getting paid to do the service, not experimenting in a junk yard on junk cars or in a lab without any real world experience or application. We have a fully stocked Automotive Exterior Repair Shop, and developed this system and kit from Professional Paint and Body Repair products.
You cannot buy all of the products in our kit for the prices we sell them because we buy all theses products wholesale for our paint repair business. We then apportion the various products to make single applications for this particular use to offer a comprehensive, completely thorough repair, from start to finish.
We offer a real money back guarantee and have maintained 100% positive feedback after selling 1000+ kits. This is because our kit really works or we really do refund your money if you are not happy as well as real tech support through telephone or emails.
One thing to consider from someone offering a solution to this problem is their feedback on eBay. Also, you should read everything written in their listings; return policy and feedback left for others; and do they work in the automotive exterior restoration field?
What do their before and after pictures look like? How many do they have and are they detailed pictures or small indistinct pictures? Do they offer contact information and do they respond to questions frankly, thoroughly and honestly?
If you found this information helpful, please vote. This will help us keep this information up to date and edited as needed!
Thanks for reading.
Sources- Wikipedia and Dictionary.com and- our own automotive paint repair experience and training