Can soft plastics be polished with abrasives ?

[Stephen Tashiro]

Can soft plastics be polished with abrasives ? For example, soft plastic toys and parts sometime have "mold lines". Can these be removed with a rotary tool and some sort of abrasive paste ?

[John T Barker]

I don't know if they were soft plastics but I applied for a job making orthotics and part of the interview process was a few hours doing the work. Essentially they cut the plastics pieces to shape and sand them to final size and take off all sharp edges.

[al heitz]

I know you can remove scratches and polish the surface of plastics and some glass by simply taking a bit of toothpaste and rubbing it out with your thumb or a piece of cloth. There's enough fine abrasive in toothpaste to act like fine rubbing compound. It leaves a very smooth, shiny surface. I use it for scratches on my watch face. Also works to eliminate the "haze" that develops on the lens of your car's headlamps. I learned the trick from my father, who used to work for a glass company.

[John K Jordan]

Can soft plastics be polished with abrasives ? For example, soft plastic toys and parts sometime have "mold lines". Can these be removed with a rotary tool and some sort of abrasive paste ?

How soft is the plastic? Like rubber or harder?

I do know acrylics and other plastics can be sanded and polished. I don't know if they are as soft as you are discussing, but they can be scratched pretty easily.

I have used the Micromesh series of fine sandpaper abrasives to put an optically clear finish on plastic.

Lately I've been turning Christmas ornaments from colored acrylic plastic using the wood lathe. I use water to wet sand it with 400 through 1500 sandpaper then use a metal polish on a soft cloth while spinning on the lathe. Here are some recent photos:





With plastic soft like rubber I might try sanding with a little disk on a Dremel. If that made it smooth, I'd then try one of the small polishing disks with a little polishing compound. I have also welded and smoothed the seams of certain plastics with heat (on a temperature controlled soldering iron) but that is tricky! I know some plastics are flame polished in industry but when I experimented with this it was a disaster!

JKJ

[Wayne Lomman]

Generally, the softer the material, the more difficult to polish. That's why diamonds have the ultimate sparkle balsa not so much. Give it a go in an unseen area and see what happens. Cheers

[Stephen Tashiro]

How soft is the plastic? Like rubber or harder?

I'm interested in plastics as soft as rubber and softer - like toy plastic animals. I'm not after a highly polished reflective surface. For example, if I sculpt a toy dinosaur and cast it in a multi-piece mold, it would be nice not to worry so much about the mold seams that are left. I'd like to polish them off, so the whole figure has about the same surface texture, which need not look like glass.