Sanding and Buffing Solid Surface Countertops

      Professionals share views about grits, buffing compounds, tool technique, and more. July 25, 2005

Question
I am sanding Corian with 120, 180, and 220 grit sandpaper on a Dynabrade 5" air sander. I am going, north, south, east, west, then using a 45 Degree Maroon Scotch Brite, and then Hopes polish. My end result is uneven finish, and I am only looking for a matte finish. Does anyone have any suggestions on an easier way? What am I to do if it were to be a semi or high gloss? Any help is appreciated.

Forum Responses
(Laminate and Solid Surfacing Forum)
From contributor S:
I would include 150 grit sandpaper in the series you use. Then I would use the Abralon 180 and 360 grit discs. They even the surface for whatever else you do to finish.



From contributor R:
Make sure you clean off the dust between sanding steps. 3M makes a product called Trizact that has a very uniform grit on film that measures in Micron.


From contributor B:
I would stop using the Scotch Brite. I'm almost positive that is what is causing your problem. Use Trizact, and then use a dry stick for the buffing compound to get the sheen you want.


From the original questioner:
To contributor B: What is dry stick? Im not familiar with it.


From contributor B:
It's a buffing compound that comes in a stick form. You load the buffing pad with it and it allows you to see the polish as you go.


From contributor H:
If you are looking for a matte finish, I would stay away from the buffing idea. We use mostly micron paper and abranet. Our standard would be 120 grit sandpaper at the seams or scratched areas, then 100 mic, 60 mic, grey Scotch Brite, and this works very well most of the time for a matte finish.

On occasions we will use maroon Scotch Brite, and then grey to help if it is clouding up on us. It usually clouds on darker colors, and we will sometimes even take it to 30 mic. We just finished a job that we had some problems with the finish, but we went back to maroon Scotch Brite and then grey and it cleaned it up very well. Sometimes it just takes some trial and error. Cleaning between grits is a very good idea.



From contributor B:
To the original questioner: Below is a link that shows what I'm talking about. They call them bricks and tubes. Once you learn how to use them, you'll get a lot more consistent finish than you will with Scotch Brite, and in a lot less time.

http://www.gruber-systems.com/products/supplies/default.htm



From contributor P:
We use 120 grit, 220 grit, 100 micron, 80 micron and 500 grit Abralon. We don't always use all of the steps and sometimes we start right at 100 micron and go from there. We think the real trick is the 500 grit Abralon. It doesn't really sand much, but it brings up a nice shine in a hurry. We use 5", 6", 8" and 12" sanders for different areas depending on what we are doing. Remember to always clean off the entire top between steps.


From contributor S:
To the original questioner: If you are using standard grit paper, I would use 120,150, 180 and then maroon Scotch Brite. If you want a little better finish then add 220. The only other problem I see is your method. I suggest going east-west, and then north-south making sure to overlap 1/2 the pad. The next thing you need to do is sand in a circular motion clockwise. If you sand counterclockwise you will leave pigtails. This is because you are working against the sander.

I also suggest that you use the Scotch Brite wet. The only other suggestion i can make is to use Micron paper. Because of the grit on the micron, you can do it in fewer steps. Use 80, 60, and then Scotch Brite and add 30 micron and use grey Scotch Brite instead of maroon on darker colors. Make sure you wipe all the dust off in between each grit. The dust left on the top is the same grit as the last grit used. This is for a matte finish.

If you want a high gloss finish, I suggest you use Trizact from 3M. After either the 220 or 60 micron, instead of going to Scotch Brite, go to the Trizact. Green, Blue, Orange and then White. Make sure to use the same method with all grits. Trizact needs to be used with water. Make sure not to soak it, just mist it. What you want is the dust to mix with the water to make a slurry.



From contributor M:
To the original questioner: As I expected there are as many variations and opinions on finishing as there are fabricators. In my experience, there is no one best way to achieve a good finish. If you are using good equipment and good quality abrasives, the rest is technique.

The issue of coverage has been discussed; whether you use a north-south east-west pattern, or a circular or cursive pattern, or a combination of each, it is imperative that you achieve complete coverage with all grit used. Cleaning has been brought up as well; it is very important that you clean thoroughly between grits to remove all grit particles from the previous abrasive.

Another thing that I believe to be very important hasnt come up in this discussion and that is pressure. The amount of pressure applied to the sander has quite an impact on the final finish. You can stop a random orbital sander from sanding in its tight concentric orbits (random orbits) by applying too much pressure. The sander will still spin, but essentially it sands like a rotary sander at this point.

A neat trick to ensure you are applying the right amount of pressure is to draw four vertical lines on your sanding pad with a sharpie marker. Put the marks on the front, back, left and right of the pad. When sanding your countertop, these marks should produce a strobe affect. If they dont, you are pressing too hard.

Pad density is another consideration; we use a softer (11/16) backer pad on our finest grit paper. These pads are less aggressive than the low profile (3/8) pads.

As for our choice of papers, about a year ago, we replaced our micron abrasives with another 3M product. It is a standard graded abrasive on a film backer manufactured by 3M in the same manner as micron. The best thing is that it is about half the cost of the micron paper. Below is a link if you have any interest.

For a matte finish, we use 180-grit to 220-grit then follow with a maroon Scotch-Brite (wet). We add 400-grit and use a gray Scotch-Brite (wet) for a semi-gloss finish. We keep on hand Trizact, Abralon, Micro Mesh, etc. We use these on a limited basis for specific colors and/or high gloss finishes.

3M Abrasives
http://cms.3m.com/cms/US/en/2-188/kriilFR/view.jhtml



From contributor C:
I'm trying to get high gloss on black Corian. I used 220 grit on an orbital sander, and then 400 and 600 grit paper by hand. I then tried putting a wool buffing disk on the orbital sander, and used a couple of different buffing compounds (including one automotive compound from turtle wax), but it's just not working. Can someone tell me exactly what I need to make this work?


From contributor J:
I think you everyone is working too hard. We use a porter cable 6" sander with hook and loop pads from Mirka. Make sure the pads are flat and the bearings are in good shape. If the sander has been dropped or abused, one or the other of these probably needs to be replaced or you will get big smiley faces on your top and create more work for yourself.

I use 150 grit or 80 micron to flatten seams and remove any scratches. I then switch to 220 grit/60 micron to remove the inline scratch pattern from the factory. Make sure you keep the sander flat and move in a slow, consistent pattern. Go north-south, then east-west over the entire top covering all edges twice.

Consistency is the key. You cannot stare at the ceiling or chat with your partner while doing this. After the 220 grit, move to 320 or 400 grit and repeat the process, then finish with a grey Scotch Brite or a 360 Abralon pad by Mirka. This will give you a finish somewhere between matte and satin. Our customers are very happy with the appearance and the maintenance. For dark colors, I mist the top with soapy water and spend a little more time with the final step.



The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor T:
I use an 11" gem sander to finish tops, micron 60 wet trizact green, then gray ultra fine scotch bright. Use water and wipe clean in between sandings. Result is a perfect matte finish. If you want high gloss, use fine buffing compound with scotch bright.



Comment from contributor D:
I used a 6" sander and got the same uneven finish with every sandpaper in the book. I switched to a Gem 11" and it comes out almost perfect and in a fraction of the time.


Comment from contributor R:
Your initial grit is by far the most important. Put some alcohol or water on the surface after the first step and make sure the color looks good at the roughest grit before going up. The next steps will be much quicker if the first was done thorough. If not you won't remove the cloudy color until you go back to the beginning step. To the person trying to get a gloss finish - you will need the right compound to make it work. In other words if your compound is a finer grit then you may need to sand it higher before the compound you have chosen will work. The most aggressive compounds seem to work much better if you stop at 600 grit. You are just barely in the window needed so make sure it is sanded well at 600 and the use a fast cutting compound.


Comment from contributor A:
I have had success with using 120, 220 grit, and then maroon and lastly gray Scotch Brite. The best finish comes from an air sander as it does not mark the edges like electric.


Comment from contributor O:
If you are looking to renew a gloss or semi-gloss finish to Corian, then begin with wet/dry 1000 or 1200 grit paper and progress to 2000 grit. Then finish with 3000 grit. The latter will produce a very high polish but you can go one step further with a commercial polish such as Soft Scrub. The high grit sandpapers are available at auto paint stores, but they are a little pricey.



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