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Old 05-15-2011, 04:15 PM
Laurentius's Avatar
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Default Polished concrete tables.

Hi Everybody,

I need info and photos. Today I'm enlarging my foundation and planing on including a table of polished concrete. Recently someone posted some beautiful photos of their work. I done numerous searches and have come up empty. I interested in colored stones, pottery shards and glass or a combination. Thanks in advance.
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Old 05-15-2011, 08:48 PM
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Default Re: Polished concrete tables.

Try this one http://www.fornobravo.com/forum/2/fi...d-15373-4.html (finally finished)
#34

Mike
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Old 05-16-2011, 02:43 PM
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Default Re: Polished concrete tables.

Laurentius,

Here's the best site I've found for ideas. There are also a number of Fu Tung Cheng how-to videos on youtube that describe the process and some of the materials, including the polishing.

CHENG Design
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Old 05-16-2011, 04:36 PM
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Default Re: Polished concrete tables.

Quote:
Originally Posted by Laurentius View Post
Hi Everybody,

I need info and photos. Today I'm enlarging my foundation and planing on including a table of polished concrete. Recently someone posted some beautiful photos of their work. I done numerous searches and have come up empty. I interested in colored stones, pottery shards and glass or a combination. Thanks in advance.
Polished concrete is supper simple once you get the hang of it. Things like semi precious stones, glass, and soft metals look beautiful in polished concrete. Pottery shards/ceramics not so much because the polishing process will likely take the thin glazed (colored) surface right off and then leave not so exciting white ceramic. Hard metals like stainless steel are a bit more difficult because they don't hone down as easily as the concrete, but aluminum and copper work really well. refer back to the above referenced post for some additional tips.

Good Luck!
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Old 05-16-2011, 04:47 PM
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Default Re: Polished concrete tables.

Help me out Nic. I know how to pour them and finish them, but nothing about grinding them. I plan on using a 7" polisher/buffer on mine, running from 80 grit in some spots through 120, 220, and finishing with ? I need to remove from 1/4-3/8" in discrete spots to an 1/8-1/4" overall. I am not looking for a highly polished finish, just smooth with more or less evenly exposed aggregate.
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Old 05-16-2011, 05:41 PM
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Default Re: Polished concrete tables.

I wet polish all of my concrete with 5" and 7" wet polishers. You will do the majority of your "cut" with the 80 grit, get the exposure to within 75% to 80% of what you want to expose with the the 80 grit, the first 1/8" will come off very fast, after that it slows down as you cut into the aggregate. Then I follow up with increasingly finer grits, typically with diamond pads the grits go 80, 100, 200, 400, 800, 1200, 1600, 3000. I will only polish to 200 grit on day 1. After 200 grit you will have minimal removal of material, mostly just increasing degrees of shine. The reason i stop at 200 is that i like my surface to dry at this point so i can see if there are any pinholes in the concrete that have been exposed or if there are any swirl marks from the 80 grit that did not get polished out in successive polishes.

If there are pinholes, I fill them with a slurry coat (Portland cement, Tammsweld acrylic admix and color) screeded in with a putty knife. Let cure 24 hours and polish out with 200 grit, 80 and 100 grit are too aggressive.

If there are swirl marks I go back to the 100 grit and 200 grit to polish out the swirl marks.

When I am happy with the surface at 200 I proceed to finish to a minimum of 800 grit but prefer 1600, personal preference at this point.

One of the hardest things to remember for people starting with polishing is to keep the head of the polisher flat to the surface. If you tip it up on edge it will cut faster but your surface will be very wavy, it is almost impossible to get the swirl marks out and it will wear your polisher bearings and pads out very fast.

You will spend most of your time on the 80 grit pad getting close to your desired exposure. Assuming your surface is exposed evenly and flat, you will only need to spend about 2 to 3 minutes per square foot with 100 through finish grit.

When Polishing concrete and stone water is your friend! I operate the polishers at their full water capacity, it keeps the dust down, washes the surface as I go and lubricates the disks so they last longer.

I hope this helps.
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Old 05-16-2011, 06:21 PM
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Default Re: Polished concrete tables.

Nic,

Good information, thanks. There is no substitute for experience with these mechanical processes. Do you have any advice in obtaining consistency with color? The scariest part of the whole countertop process that I have come across is exposing the concrete fibers to the counter surface. Do you include these kinds of fibers in your mix?
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Old 05-16-2011, 06:47 PM
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Default Re: Polished concrete tables.

Modern fibers do not expose themselves. That was a problem with glass fibers, but they have been replaced by poly fibers.
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Old 05-16-2011, 08:19 PM
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Default Re: Polished concrete tables.

Just make sure the microfiber is well distributed. Clumpy bits when mixing by hand or in a portable mixer will tend to stay clumpy. Bad juju for getting a nice finish.

I like a diamond cup wheel on the wet grinder to get the surface down to where you want it. A quarter or 3/8 inch definitely warrants this treatment to start, IMO. Much faster. Once you've got it even and down to the level of aggregate exposure you want, then move on to pads.
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Old 05-16-2011, 08:23 PM
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Default Re: Polished concrete tables.

correct, poly fibers do not expose themselves as bad as fiberglass, plus if the poly fibers do expose you can hit them with a torch and they will melt off the surface. But they are expensive, and I rarely use fibers because my design mixes end up at such a high PSI. If I'm doing a thin pour (1.5" or so) or an upside down precast pour i will do a backer coat with fiberglass fibers, but cast in place work really shouldn't need fibers.

color consistency is only achieved by being precise and consistent. Meaning I weigh every component that goes into a batch down to the 1/10th of an ounce. also mixing time is very important, the only way to achieve a good counter top mix is to use a mechanical mixer and to let it mix for several minutes past when it looks done.
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