Restoring the Surface of Acrylic

Hi May i know what's the easiest way to restore the surface of a piece of acrylic that was previously milled?

Can i make it transparent again just by sanding or do must it be buffed? For the former what is the recommended grit size to start with?

Thanks.

Reply to
Philip
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"Philip" wrote ..

You need to buff with a cloth wheel. Sanding will only make it translucent, but sanding may be necessary before buffing.

Reply to
John C

You may want to do a web search for chemical polishing or solvent polishing. Basically, you use a chemical vapor to soften the scratched surface and let it flow just enough to remove the scratches.

Reply to
ms

Progressively finer grits then rouge seems to work. There are polishes intended for light aircraft windshields (maguire) that are effective for light scuffing

Brian Whatcott Altus, OK

Reply to
Brian Whatcott

Or if it's only litlle progressively finer emory paper followed by rubbing with a soft cloth and T-cut (or any other slightly abrasive cream designed to fair-in paint patches) is pretty effective ( but requires some practice).

Best of Luck - Mike

Reply to
Mike Yarwood

The plastics supply house that I occasinally buy acrylic sheet from has different edge treatments available;

sawn, beveled, buffed clear & something called "flamed something"

My guess is that they heat the edge to approximate the clear buffed result at a fraction of hte cost.

I've never tried it, maybe you could experiment with some scrap

cheers Bob

Reply to
BobK207

" May i know what's the easiest way to restore the surface of a piece of acrylic that was previously milled?

Can i make it transparent again just by sanding or do must it be buffed? For the former what is the recommended grit size to start with?"

How rough is the surface? What I've done in the past is to start off with 400 grit wet/dry sandpaper, and WET sand the surface. Then progress to 600, 1000, and 1200. WET sand, and don't go to the next step until all the scratches are removed from the current grit. If you're not happy, then you could try glazing compound like they use for car finishes. Be very careful if you do this with an electrical buffer

- it is very easy to overheat the surface of the plastic which will mess it up.

Reply to
'lektric dan

That's my question too. It looks like a matt surface but is smooth to touch. What grit size should i start with in this case?

What I've done in the past is to start off

what kind of surface can i expect for a 1200 grit size?

thanks.

Reply to
Philip

Try the 600 grit. This will give you a smooth surface and you can tell if you need to go back to 400. It's important to wet sand, and do it by hand either using a sanding block or by sticking the sandpaper to a glass plate. You want to avoid heating up the plastic while sanding.

1200 grit is what's used for final color sanding on cars. It's extremely fine, probably the finest grit you'll be able to find in sandpaper. I don't know what you're looking for; it may not be good enough for optical work, but is good enough for appearance. When in doubt, try all of the above with a scrap piece of plastic
Reply to
'lektric dan
3M Imperial Wet or Dry comes in grits down to 2000. I spray adhesive on the back of it, stick it to a plate of glass and use it to put a razor's edge on my chisels and handplanes, and to lap heatsinks and such. It will polish most metals to a mirror finish, but plastic is tougher to polish. For plastics I have used Novus plastic polishes. They come in 2 grits of abrasive polish, and a final nonabrasive polish. I have heard it works quite nicely on acrylic. I polished a plastic watch crystal using this with felt polishing wheel in a Dremel tool, and it came out, um, crystal clear. The final polish also works well on the DVD's that my 4 year old daughter has scratched up after playing 4000 times. This is impressive, since polycarbonate plastic is especially tough to polish.

You can find the Novus plastic polishes here:

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Reply to
MSU Spartan

Someone in another newsgp suggested micro mesh:

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I wonder how its mesh 12,000 compare with novus 2. Anyone with experience using both?

Reply to
Philip

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