I have had to polish headlights on several cars. It began with my Nissan Tino where the ominous advisory ‘ Headlights discoloured not affecting output’ appeared . I thought naturally I will be stung for two new headlights next year then… So I started cheaply and followed well meant advice of rubbing toothpaste, baking soda,chrome polish etc. These were pretty ineffective. Then experimental chemistry one sunny afternoon on tiny areas to see if I could reverse signs of yellowing. I masked off tiny patches of lens and tried a variety of test solvents and reducing agents to counter the effects of ageing. If successful I thought I would make my fortune on Dragons Den! ( Well the solvents must have gone to my head, Not recommended, total failure and I nearly softened the plastic in one attempt). So I came to my senses and reverted to buying a Gunson Kit from Halfords. Effective but quite slow progress and hard work. Also as I tired from rubbing the lenses carefully, I became careless, rubbed harder strayed and caught the paint on the edge of the car wing very slightly. Finally I achieved the correct combination of speed and pressure and it worked well. I really liked the end stage three Gunsons item which in those days was a bottle of liquid that gave a bright finish to the lens like new. Clever science, it seemed to be a liquid with exactly the same refractive index as the plastic lens thereby making minor scratches completely invisible. Indeed for a lens with only very minor fine scratches if you are pushed for time you could probably just put a drop of this on half hour before the test for 90% improvements and little effort, but it would revert to a pumpkin at midnight!
With later cars I have used the very effective Megulars G 1900 type kits with their small polishing head and my variable speed electric drill. If a scratch is deep I use I use small pieces of wet and dry paper wrapped around a suitable pad, until the scratch is much reduced. I don’t start with a really coarse paper but begin with say 1200 and then only use a coarser wet and dry if it’s not working. I always dip my home made buffer in a small bowl of clean warm water with fairy liquid in it, and work the abrasive transverse to the scratch. ( The pads with abrasive don’t last you for more than a year before the abrasive weakens, but the Megulars polish bottle has lasted quite some years. The megulars Plas X polish on the electric drill mop works well on discolouration and oxidised layers, and is ok on modest scratches so I find that use of the wet and dry is only needed for a deeper scratch. ( Of course these days I well tape off the adjoining wings!. After washing all residues off and using the Megulars final protective potion, I still use a final drop of the magic remaining Gunsons finishing oil as a final touch. I see they no longer supply a bottle but give you two small sachets. I can’t blame them, too many people like me keeping their car cupboards full of opened items just in case… Finally it’s best to do this task just a day or two before the test as the magic protective coating effect with the products I have tried only lasts a short time as others have mentioned. PS The cerakote used by the lard boy looks so great on the headlights for less effort, I will try that one next year,but it sure made his windscreen look terriblycloudy🤡!
