Make-It Monday: Failed attempt to defog headlights

I keep seeing these dramatic before-and-after photos on Pinterest that show how you can defog old plastic headlight covers using cheap toothpaste.

I was pretty sure this was crap the first time I read it, but I figured it was worth a try, since the headlights on the Dreamcar were covered with black walnut sap, the plastic was yellowed, I’d gotten overspray on them after forgetting to mask them off last time I painted the hood, and toothpaste costs a dollar a tube. If it didn’t work, I was going to have to replace them anyway, so why not give it a try?

Have I mentioned how much I hate the black walnut tree next door?
Have I mentioned how much I hate the black walnut tree next door?

Following several sets of instructions I found online, I applied some Ultra-Brite toothpaste to the headlights with an old toothbrush.

Here we go.
Here we go.
Totally covered.
Totally covered.

I scrubbed it around with the toothbrush for several minutes and then hosed it off. The sap came off, but the plastic still looked pretty bad, so I took some advice I found on another how-to-clean-your-headlights post and reapplied the toothpaste, using a Scotch-Brite pad to scrub it off.

When I rinsed, it looked pretty good — not perfect, but less yellow, maybe, and most of the overspray came off — but as the water dried, the plastic fogged back up and looked worse than it had to start with:

I'm not sure this is an improvement.
I’m not sure this is an improvement.

Back to Pinterest. A commenter on one of the how-to articles I’d found suggested applying olive oil. Another suggested vinegar. I’d made a pretty effective furniture polish out of a mixture of the two and still had some left under the sink, so I ran in and got it. Definitely an improvement:

Shiny again. Sort of.
Shiny again. Sort of.

Another commenter said the best method was to attach an old sock to a belt sander, put the toothpaste on it, and use it to buff out the scratches. Several commenters agreed with this, so I found a worn-out running sock and gave it a go.

At least I'm recycling.
At least I’m recycling.

Buffing seemed to help some, and I suspect if I’d done it first — before I took out after the plastic with that abrasive Scotch-Brite pad — it would have helped more, but I was still underwhelmed.

Yet another commenter insisted WD-40 is the way to go. Well, of course. Anything that can’t be fixed with WD-40 or duct tape belongs in the trash. I rummaged around under the kitchen sink, found my WD-40, and applied it, buffing it in with a fresh sock on the sander.

This was the result:

I swapped sap and discoloration for scratches.
I swapped sap and discoloration for scratches.

Not bad at first glance. Maybe an improvement. But as soon as it rained, they fogged up again and looked like frosted glass in the dark — very pretty, but I’m not sure you’re supposed to drive with a Streisand filter* over your headlights.

Conclusion: This method is, indeed, utter crap. The sock on a sander might work without any of the substances I applied, but the toothpaste and Scotch-Brite just scratched up the plastic and made it worse. I’d also be leery of using anything abrasive or acidic near a factory paint job, as I’m not sure what it would do to the finish.

Pinterest fail. I’ll take the Dreamcar to the Honda dealership next weekend.


*My friend Brandey’s term. We used to watch a lot of old Barbra Streisand movies, and Brandey noticed the cinematographers always used a soft camera filter on her close-ups.


2 thoughts on “Make-It Monday: Failed attempt to defog headlights”

  1. I’ve heard bug spray works, but haven’t tried it. Also heard Pledge furniture polish. There’s a guy here in town that does them for about $30 and guarantees his work.

    1. I hesitated on the bug spray because I’ve heard it melts the plastic and makes it worse. I tried it this morning, since they’re shot anyway; results looked about like the WD-40. I’m guessing it’ll fog again with the first good rain.

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