Polishing concrete

[gjbingham]

Re: Polishing concrete

Anybody have goat's milk?

I wonder where you can buy that around here? It sure is pretty stuff!

[gjbingham]

Re: Polishing concrete

OK, so everybody's looking for some folley, huh. I got abused by Ken and Dave for withholding pics of my polishing efforts, so suffer through these:

I bought this wet grinder on Ebay. It's a total POS (piece of sh....). Supporting documentation is nil. The parts don't fit together well. No adaptor for the hose connection...... Suffer through that and you can polish concrete for 120ish bucks. It does have variable speed and diamond pads up through 3000 grit, plus a buff. I'm not sure if you get what you pay for or not, but it does work.

Polishing concrete is a long process, but kind of fun, if you're the kind of person that likes watching the grass grow.

My landing was poured from two bags of Quikrete 500, with a bottle of terra cotta stain split between the two mixes, which were mixed separately. Despite my best efforts to equalize the stain into each mix, they were totally different once mixed. You can see that the top of the landing is more red than that below. I tried during the pour to push or mix the upper, second mix into the first with rebar. It didn't work very well (or at all).

The webpage posted earlier for polishing concrete recommends doing all polishing between 10 and 28 days. I'm outside that window due to weather and other delays. I polished it initially out to 1500 grit but developed/exposed a lot of internal porosity along the way. I finally made a slurry mix of Portland cement and stain and rubbed it into the porosity, waited 10 days, then repolished yesterday.

Slight irregularities in the levelness (is that a word?) of the landing created a small valley about 4 -5 inches out from the entryway. As I ground out the high spots, the aggregate of the concrete from the higher portions became more exposed while that of the lower spots didn't. This is still visible in the photos, but not nearly as apparent when looking at it. It looks pretty cool, like Corian countertop, at least if you've had a couple of beers.

I didn't expose as much of the aggregate when polishing the front, so the appearance was a little irregular. I decided to start over on that surface (yesterday) and hit it with the 50, 100, 200, and 400 grits. More porostity exposed!

As I said previously, I keep soaking the bricks of the entryway. I decided a couple of weeks ago not to fire up the oven again until I got this polishing done. I can't imagine it's good for the bricks to keep wetting them, then heating them up.

The polishing is going on too long, so after seeing the new porosity on the front of the landing, I opted to finish the top of the landing, then dry out the oven and cook again. Polish the other sections whenever time and weather allows I think I can do these sections without getting the entryway wet. The entire landing is dry, the front is only polished to 400 grit, the top is done, at least for the time being.

The bad news is my wife likes it. She wants me to do the rest of the BBQ and bar tops in poured/polished concrete. "What else are you going to do with your time" she says.

Soooo, that's my fun recently, as it were. Lessons learned for polishing concrete:

- pour about an 1/8th inch more concrete depth than you need.
- mix all concrete at once to achieve a consistent color, or devise a better way to ensure that you get equal amounts of stain in each batch.
- polish the entire surface to 400 grit, then do the next higher grit once each day. That way you can evaluate you existing polish level dry, which is impossible when you are grinding wet.

[asudavew]

Re: Polishing concrete

i think it looks great!!!

definitely the way I'm going

[edschmidt]

Re: Polishing concrete

Looks good, Insted of mixing stain into the concrete I hit it afterwards with an acid stain which turned out very nice and even this way you only color it once its porousity is under control. I also threw in some marbles and sea shells (collected from various vacations) into the mix Near the surface. What are you using to seal the surface? I used the same stuff that they use on stamped concrete, it gives a nice wet look.

[gjbingham]

Re: Polishing concrete

edschmidt,
Sealing is still in the future. Do you know the name of the product? I'd love to see pics of your acid stain work. I'd read about it, but not extensively.

Dave,
Glad you approve. Don't expect immediate perfection. You may end up doing it several times, as I did before you get satisfaction.

G'night!


George

[jwnorris]

Re: Polishing concrete

<snip> Polishing concrete is a long process, but kind of fun, if you're the kind of person that likes watching the grass grow. <snip>

While I have not been directly involved in pouring a concrete counter, I have witnessed several. Here are a couple of thoughts.

All of those that I have seen used a stain applied after the pour and polishing. If doing additional counter beyond the landing, try to do all of the staining at the same time.

A dry mix seems to be important. Packing it into the form is very important - it must be tightly packed. This step is important and you'll find that you used mussels that you did not use building the dome.

Spending some extra time tamping the top with a float and spending extra attention to the sides of the form is also important. Bang on the sides of the forms as a way to vibrate the sides. This helps reduce any air pockets or bubbles. These actions tend to drive the aggregate away from the surface and should reduce popouts and voids when polishing.

Hope this helps.

J W

[CanuckJim]

Re: Polishing concrete

George,

Benjamin Moore makes an excellent product called "Concrete and Stone Sealant," which I've used on exterior flagstone with good results. Concrete has to cure 28 days before sealing, though. The first coat will go to a flat finish after about three months. I like that look, but if you want a shinier effect, just recoat.

Jim

[Ken524]

Re: Polishing concrete

George,
I'm sold. That looks great! (I'm also a big fan of Quikrete and watching grass grow).

Can you post the eBay link of the vendor that is selling the grinders? I did a search for "POS Wet Grinder" and didn't have much luck .

[RCLake]

Re: Polishing concrete

The bad news is my wife likes it. She wants me to do the rest of the BBQ and bar tops in poured/polished concrete. "What else are you going to do with your time" she says.

So all your free time isn't baking pizzas, breads or briskets???? I would have thought that would be enough.

Like the polished concrete, may go that way as well - but first I need to get done.

[gjbingham]

Re: Polishing concrete

Jim,
Thanks for the sealer info. I'll seek it out.

Ken,
Great laughs! My wife thinks I've lost my mind as I sit here grinnin' and postin'. I wasn't kidding about what a piece of junk it is, but the seller offered full refund for 30 days while talking to him on the phone. I does work, and I guess that's all that matters. Try "wet polisher" or wet grinder. You get the same things. Put a low-ball bid ( a couple of bucks higher) in the last couple of seconds before the auction ends on any that still have a reasonable price.