How about clear nail polish? Put it on the clean dry surface and buff it smooth while it's wet, wiping it with some plastic wrap. I worry that all the rubbing and buffing compounds mentioned will take off any shine you had.
The car polish for plastics idea is probably the best idea. I use it on my old cars headlights and dash instrument covers too.
I live in an RV and the bath fixtures look and feel like plastic but they are fiberglass. To be able to tell the difference, if your sink scratches are grey, it's probably fiberglass. Molded plastic would be the same color under the surface as the color of the sink.
If it's fiberglass, auto parts stores and RV supply stores both carry fiberglass cleaners.
Thank you for the ideas. I thought before about replacing it, but thought this were smallers than regular ones. I'll cheque it next time go to Home Depot. Thank you, and God bless you. Maria
I also live in an older mobile home with these plastic sinks & there's 3 things I know of that you can do to fix the problem. As "alloydog" said they have a polishing compound that's sold in Auto Parts Stores that will buff out minor scratches. I know because I used this stuff on my car's plastic headlights. This buffing compound comes in 3 strengths & you usually start at the strongest & work your way down.
2) For deeper scratches & gouges, you can buy a matching color of a filler from the people who make Formica countertops. This filler is made for filling in grooves in Formica & laminate countertops.
3) For under $40 you can buy yourself a brand new generic porcelain sink that will fit in the EXACT SIZE of hole as your old plastic sink. This means with very little work you can install a decent sink. Check out the cheapest sinks at Home Depot or Lowells. The usually carry 2 sizes of the cheapie porcelain "no-name" models. I know this because I paint these sinks with glaze then fire them in a kiln & resell them with my art on them. The sinks you buy should look exactly like your old plastic sink. Just measure it to make sure. The sink comes with a template so you can double check before you take it out of the box. All you need is several sizes of Vise Grips a screw driver, some Teflon pipe tape & maybe a pipe wrench for the bottom pipe to swap out the old sink.
* From now on you might want to clean the plastic sink with a spray-on bathroom cleaner (like scrubbing bubbles) I buy the dollar store brand then spray it on my plastic bathroom sink & leave it set for 10 or 15 minutes before wiping it off with a micro-cloth. For stubborn stains I simply repeat the process.
You need some sort of gentle abrasive rubbing compound.
Try toothpowder, if you can still get it. It used to come in a tin, about a couple of inches in diameter, like a shoe polish tin. Toothpaste used to be pretty good at polishing scratches out of softish surfaces, but they made it kinder to teeth and less abrasive.
Failing that, a rubbing compound from a car parts shop, such as Autosol - it comes in a gold and black tube. Just ask, they'll know what you mean.
To take out deep scratches, you need to press fairly hard, making small, tight circles with your finger. Then when the deep scratches are out, you keep polishing but using less pressure.
I also remember seeing a magazine article (yeeeeears ago...) for a polishing compound to take scratches out of plastic. It was in a motorcross magazine. You ask at a motorbike store if they know of such a product.
What every you try shouldn't cost more that a few bucks.
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