Sanding/polishing plastic

[Sanderxpander]

Hi all,

I think I read some posts on this the other day but it was a kind of derail from another thread and I can't find it now. I have a Rotex 90 and would like to "freshen up" our acrylic dual bathroom sink thingy. We were a little careless with it during remodeling and there are some stains we can't get out and lots of tiny scratches. No major gauges thankfully. I am ever lost in the world of Festool abrasives, so far I've used the Rotex only on wood and paint so the grits I have are 40 through 220, all Granat. I'm assuming all of those would be too rough for this type of thing. So what would be a good place to start and how high should I go? This isn't a set of headlight covers so I guess it doesn't need to be an ultra high grit finish. I plan to use an interface pad to help with the curves, if that matters.

Do I use Platin? Brilliant? Do I need any kind of polishing compound/fluid?

 

[nclemmons]

Have you considered the Festool polishing compounds?

They work well.  And I've used them with the RO90 and RO150 with foam and felt pads.

I've used them on finished table tops, Corian and even automobile finishes.  I have not tried them on acrylic sinks, but I believe they could work well.

You can find the range of products on this page:

https://www.festoolproducts.com/catalogsearch/result/index/?limit=all&q=polish

I have several of the pads as well as all the polishing compounds.  You could start with their 2000 or 4000 grit foam pad in Platin and wet sand with it and step up from there to the polishing compounds.  I would encourage you to not mix the pads with the different grit polishes.  They are color coded to keep them from being polluted with different abrasives.

I've found mirror finish possible with them.

 

[rst]

Heat is NOT your friend when polishing plastics.  Minimal pressure and slower speeds and water are your friend.  I work with plastics all the time but they are not counter top material.

 

[Cheese]

Where to start...
You need to determine what visually offends you and what will you accept as far as the acceptance of scratch level goes.
How deep are the scratches and how many do you want to eliminate? That’s the key.  Eliminate all scratches, eliminate only deep scratches, eliminate only visual scratches?

If this were my project, I’d start here...

Look for a small area that’s difficult to see and start with 320/400 grit. Sand it gently and then lay on some water or alcohol and look at the surface with a bright light. Are you satisfied with the results? Are the scratches you wanted to remove gone?

Scratches deeper than .003” will take paper grits in the 180 range to remove efficiently. I’ve found it easier to start with more aggressive grits and sand for 2-3 minutes than to start with less agressive grits and sand for 15 minutes.

Just take your time and run through the grits, it’s worth the extra effort.

 

[Sanderxpander]

Thanks guys, ok more detail;
The scratches arent the worst to be honest but I figure with any kind of sanding they'll improve. What bugs me more is some staining and discoloration from not properly rinsing after cleaning a paint brush and the like. Trust me I've tried all the obvious paint (and bathroom) cleaners so I feel like sanding is a good option at this point. There are also small scratches but if that was the only issue I would not be doing this.

So there's some wildly differing advice here - try 320 grit, start with 2000 grit etc. My problem is I'd rather not spend 200 bucks on abrasives and polishing compound unless I need it. I don't mind buying them but if I should do, say 320, 500 and 1000 that's a different story from doing 1000, 2000, 4000 and some polishing compounds.

So what would you do?

 

[Gregor]

Look for a small area that’s difficult to see

As a hint: The underside (outside) might offer plenty of surface that, should it be inside a cabinet, could be used for experimentation as it'll never see the light of day under normal operation conditions.

My problem is I'd rather not spend 200 bucks on abrasives and polishing compound unless I need it.

Talk to you local festool dealer, possibly he has demo stuff from which you could get samples (free or cheap - single sheets of abrasive, a squirt of polishing compound into a glass jar to go) to test if it works on a small surface...

 

[Cheese]

So there's some wildly differing advice here - try 320 grit, start with 2000 grit etc. My problem is I'd rather not spend 200 bucks on abrasives and polishing compound unless I need it. I don't mind buying them but if I should do, say 320, 500 and 1000 that's a different story from doing 1000, 2000, 4000 and some polishing compounds.

So what would you do?

If removing the scratches isn't a priority, then you can start with 2000 and see if that does the job.

If not...move down to 1000, if yes...move up to 4000.

Not wanting to remove scratches will make this project easier and cheaper.

I recently finished polishing an epoxy coat (West) that I floated on some white oak. Because Festool refuses to sell abrasives in reasonably sized quantities, sometimes you just need to be creative.

The first photo below shows the abrasives I used on an ETS EC 125 fitted with a 150 pad.
120.....150mm Granat
240.....150mm Granat
320.....125mm Brilliant 2
400.....115mm X 125mm Granat foam pad
600.....115mm X 125mm Granat foam pad
1000...125mm disc cut from 3M Wetordry
2000...125mm disc cut from 3M Wetordry

[attachimg=1]

The 2nd photo is a shot of the white oak slab to verify that this mix and match approach will work. [big grin]

[attachimg=2]

 

[Sanderxpander]

Thanks for the tips! Yeah that's exactly my problem, I probably need only one pad of each grit and would have to buy boxes of 50 or 100 (or 15 of platin). I have grits up to 240 so I could definitely erase deeper scratches. My thought was that that's much too rough for plastic.
When you say you used the foam pad, do you mean you hand sanded or did you somehow attach it to the sander?

I hadn't even considered buying non Festool paper, which is dumb cause I doubt dust would be a problem. Perhaps other brands sell smaller quantities, I do have a store I could try.

 

[Cheese]

When you say you used the foam pad, do you mean you hand sanded or did you somehow attach it to the sander?

I just carefully centered the foam hand pad on the ETS EC 150 pad. The vac will help to hold the hand pad in place. Just make sure it's centered or it may try to fly off. The 3M Wetordry is the same issue.

With no holes in the foam pads or 3M Wetordry to evacuate the fines, I just kept wiping the epoxy surface with a clean microfiber cloth and vacuumed the abrasives often. When you get to the 400 level and up, the fines are just like dust so it's relatively easy to remove them without holes in the pad.

If I had my druthers, I'd have used the correct abrasives from Festool, however, that would have cost an additional $250 for 5 lousy pieces of sandpaper.  [mad] [mad] [mad]

Here's another shot of the finish. The overhead LED lighting, stainless pan on the range and the stainless tile backsplash are all reflected in the surface. If I had wanted to go further, a spin with 4000, 8000 and some 9000 compound would have produced a mirror surface for sure.