Concrete Bar Top

[thomas_oehlke]

I do not know exactly what topic this gals under on this website so I apologize if it is in the wrong spot, but I currently poured (poured on 1/30/2020) a concrete bar top in a mold and it’s my first one I’ve ever done so the troweling looks a little rusty but that’s past the point. I came onto this forum because I made the rookie mistake of sanding the concrete with too coarse of sandpaper, if I’m even suppose to sand concrete, while it was still green/wet. I now have slight scratches all over the top from the orbital sander I used. I was using 120 grit thinking it would be fine enough not to scratch it but once I sanded the entire thing and blew the dust off with an air compressor, all the scratches appeared. I’ve tried using a little finer sandpaper and eventually very fine sandpaper but no difference was achieved. I am planning on acid staining it brown and sealing it with many coats but I want to know if there’s something I can do to get rid of those scratches before I stain and seal it, unless staining and sealing it eventually will get rid of them. I’ve included pics of the bar as of now after I wiped it off with water and paper towels. If anyone knows any good advice to remove those scratches, it’d be greatly appreciated because I’m ready for my next step as soon as someone reaches out to me. Thanks.

 

[MFolks]

If it were me,I'd put the molds back on and pour another thin layer,troweling it smooth,and then do the finish work after it cured.

 

[nadogail]

Look into Thin Set from a flooring supplier.

 

[Crushtang]

How's the underside look? Maybe you could flip it over and use that.

 

[Hooked]

Get you a set of these(or similar) and you won't be disappointed with the finish.
https://www.amazon.com/dp/B0056JHCPG/?tag=atomicindus08-20

I used the granite version to make a lazy susan for my daughter using the sink cutout. Amazing results.

 

[thomas_oehlke]

1) If I put the molds back on and poured another thin layer, I’d have to add more remesh but if I did it too thin, it’d probably chip off eventually. I’d rather lice with these minor scratches than do all that and risk it chipping away, thanks though!
2) I’m not looking to add anything else onto it except for stain and sealer. I’d like to know more about how exactly thin set works before I would ever try it. Thanks.
3) When I poured it, I had 1 1/2” foam on the underside to make it lighter and create an apron around the edge so it actually looks 3” thick but only the majority of it on the inside is only 1 1/2”. I used 3” side walls for the mold.
4) This looks like the most interesting and most appealing idea to me, but I’d like to know more. Like I said, I’m a rookie with pouring concrete so with these polishing pads, do I need some other tool in order to do that? Or how exactly does one polish a concrete bar top?

Thanks everyone for reaching out

 

[PCustoms]

Get you a set of these(or similar) and you won't be disappointed with the finish.
https://www.amazon.com/dp/B0056JHCPG/?tag=atomicindus08-20

I used the granite version to make a lazy susan for my daughter using the sink cutout. Amazing results.

Didn't click the link, but I'm using stadea from amazon on my project. Works very well, key is keep it wet and keep flushing the sludge.

 

[Farmall450]

The pros would wet sand that out

 

[dfiler2]

Get you a set of these(or similar) and you won't be disappointed with the finish.
https://www.amazon.com/dp/B0056JHCPG/?tag=atomicindus08-20

I used the granite version to make a lazy susan for my daughter using the sink cutout. Amazing results.

Do this^^^

I did a vanity top for my shop bath room, bought a $70 polisher from Menards
https://www.menards.com/main/tools/...her-sander/pp180tu/p-1444451079593-c-9075.htm

...and those diamond polishing pads from the above post, turned out great. You can start with the roughest pad and get those scratches out easy. I don't think you'll be happy with it trying to pour over the top.

 

[El Bicho Malo]

Depends how much you can live with. You could grind through that to smooth it out with diamond pads and water, but they are expensive, and you might burn through to the aggregate.

Cheaper option, although demoralizing, would be to scrap it and start over. This time, follow the proper method...cast it upside down, so the form face is the finished face. Use melamine for the form. It will be nice and flat and have a perfect smooth finish.

 

[PCustoms]

^^^if this is a one off, scrap and start over is tour best bet.

Melamine mold $15
Tube caulk (for mold) $5
Wd49 release
RAPIDSET Mortar $17/bag
Rapidset plasticizer $4/bag

I had my biggest section get away from me and in the ed decided to scrap it. $100 worth of materials was easier to swallow then weeks of trying to fill and polish.

I decided to polish for consistency after my 1st counter. At this point I could probably pour 4 matching sections without polishing, but the slight aggregate exposure looks like stone.

 

[tncatadjuster]

The reason you got the scratches is you broke the sand out of the mix and turned you paper into 50 grit or the size of the sand that was in the mix. It could be polished out with the right grits. Even in using diamond tooling you have to completely remove all of the fractured diamonds left by the previous tooling.

Good luck.

 

[Flail]

The polishing pads work well. Just go coarse to smooth with water flushing out grit. Can use a HF polisher. I edge joined some 2” granite for a tub surround and it was impossible to do it without a slight lip. 1/2 hour with the polisher and you can’t see or feel a lip.

Also made a top with concrete. Poured it upside down and place marbles and colored glass in the form first. When cured, ground off and polished about 1/8” off the top with a nice terrazzo look.

 

[Hooked]

1) 4) This looks like the most interesting and most appealing idea to me, but I’d like to know more. Like I said, I’m a rookie with pouring concrete so with these polishing pads, do I need some other tool in order to do that? Or how exactly does one polish a concrete bar top?

Thanks everyone for reaching out

In addition to the diamond pads get you a Harbor Freight polisher (less than $40). It comes with a velcro spin-in disc and these pads attach to it. I used a low (#2-3) speed and go from coarse to fine grit making sure you get the scratches from the previous grit out before stepping to next finer grit. Although I've done my fair share of sanding over the years it was my first experience with these pads and it was easy-peasy. You really can't over grind it but with your top it shouldn't take but a couple minutes with each grit.

As you can see from the results posted above it will turn out great. Plus, you'll have a new tool and pads for another cool project.

 

[Kaizen]

Didn't click the link, but I'm using stadea from amazon on my project. Works very well, key is keep it wet and keep flushing the sludge.

I got a wet grinder and pads as well from amazon. Op definitely should invest. Start at a lower grit and progress through all of them. Only difference is you will see aggregate showing through as you are probably getting through the mud layer.


Sent from my iPhone using The Garage Journal mobile app

 

[Trochu]

I built a concrete topped desk. Haven't used them yet, but bought a polisher and pads and from what I read, would easily remove those scratches. I've read I actually need to go easy so I don't expose the aggregate.

 

[AA7483]

I used a wet grinder on mine. Fairly inexpensive from Amazon