Yellow headlamps
Q I have in the past fitted brighter halogen bulbs to my cars. The aftermarket bulbs that claim to be 50/80% brighter. Although an initial improvement on both occasions, after about six months, on each vehicle the headlights went cloudy and yellow, with a big reduction in light output. The bulbs in question were Osram Night Breakers I believe.
Also, I have tried the various headlight cleaning products, kits and methods over the years including fine (2000-grit) wet and dry paper with little success and after a few months they are yellow again.
I have a 2007 Vauxhall Astra with excellent headlight lenses but original bulbs that are now very dim that I plan to change. I have two questions. Are these brighter bulbs causing my previous headlights to yellow due to heat,
UV etc., or is it a coincidence and do you know of any headlight polishing kits/methods that are successful.
Nicholas Lett
A The reason that the headlamps turn yellow is due to the oxidation of the polycarbonate lens used in modern headlamps. The cloudiness comes from the exposure to UV radiation. Although the upgraded bulbs produce more light than the original standard units, the upgraded bulbs (the road legal ones) run at the same wattage and so do not create more heat. The extra brightness is produced by using a different gas mixture inside the bulb enabling the brighter output.
The early Ford Mondeo used a different bulb as the plastic headlamp lens would yellow unless a low UV bulb was used. Things have now moved on and this is not the case with your Astra. The OSRAM Night Breaker Laser +150% run at 55W which is the same as the standard bulb and so the heat produced should be no greater.
The colour temperature may be different, but this indicates the colour tinge of the bulb, the higher the colour the bluer the bulb will look, those in the lower band will appear to have a more yellow tinge.
There are a few good cleaning kits on the market to restore the headlamp to its original condition and the Meguiars One Step Headlight Restoration Kit which is available at this site https://bit.ly/cmoqhck for £27.50 is certainly one to consider.