Improving 'floated' finish on concrete countertop

[RichC]

I poured my concrete countertop yesterday with the help of a Brickie friend. It's just white sand, granite sand and white cement. The finish is floated, not troweled so slightly rough. I figured this would be ok as I'd easily polish off the rough surface. I'm looking now and seeing some imperfections and wondering if I should make up a mix and trowel it on to get a smoother finish. There's a few small 'very minor' hollows I'd like to fill. I'm wondering should I fill the hollows in 2 weeks when I start to polish or should I do it sooner?
Also do I need to wait 2 weeks to start polishing?
Thanks

Rich

[stonecutter]

Re: Improving 'floated' finish on concrete countertop

Nope, filling low spots will not work. Live with it or do it over.

You should wait 7 - 10 days before you polish.

[RichC]

Re: Improving 'floated' finish on concrete countertop

Thanks stonecutter, the low spots are very minimal so I'm not worried. Can't wait to start polishing and see how it turns out

[ATK406]

Re: Improving 'floated' finish on concrete countertop

There's a few small 'very minor' hollows I'd like to fill.

When you say "hollows" do you mean variations in the flatness of the surface or pin holes? I think Stonecutter is assuming the former as pinholes can be filled prior to polishing the surface (but you probably already knew that).

AT

Oops, looks like you already responded to Stonecutter's post.

[RichC]

Re: Improving 'floated' finish on concrete countertop

Atk, yes its hollows and only 1 or 2 but very minimal. Nothing I can't live with

[stonecutter]

Re: Improving 'floated' finish on concrete countertop

You could feather them out before you polish.

ATK, I wasn't referring to pin holes.

[RichC]

Re: Improving 'floated' finish on concrete countertop

What do you mean by feather them out?

[stonecutter]

Re: Improving 'floated' finish on concrete countertop

Grind the surface around the hollow...blend it in.

[RichC]

Re: Improving 'floated' finish on concrete countertop

I'm gutted!! Going to rip out the countertop and do it again. I started polishing last night just to see a sample. I picked a small patch and just did the 50grit. I was amazed at how good the finish can get and I can see how it could be truly amazing BUT the floated finish on my countertop has too many imperfections like pockmarks and small grooves. I'm going to do it again and get a good trowelled finish to start on. The mix I used, equal parts, white sand, granite sand, white cement looks great. I love the finish. Its just going to annoy me looking at it for years if I dont do it right so I'll be cutting it out over the next week or so and will start again. I know if I leave it small bits of dirt etc will get into those grooves and hollows and I'll never be able to clean them out.....Big job but the decisions been made!!

[stonecutter]

Re: Improving 'floated' finish on concrete countertop

If you cast it upside down it will be pretty close to perfect.

[Tscarborough]

Re: Improving 'floated' finish on concrete countertop

You can also make a slurry and coat it before grinding it to fill the holes and trowel marks.

[RichC]

Re: Improving 'floated' finish on concrete countertop

Can't cast upsidedown Stonecutter. Its a single piece with the oven sticking up out of the middle and sloping away on all sides.
@Tscarborough Because they're not just pinholes I'd have to put a skim coat on the whole surface. I'd be afraid of it breaking away in chunks as it expands and contracts due to weather or is that unlikely? Anyway, I reckon I can cut it out in a few hours and Repour in about a half day

[Tscarborough]

Re: Improving 'floated' finish on concrete countertop

You will grind off 99.3% of it, so don't worry about it popping off.

[deejayoh]

Re: Improving 'floated' finish on concrete countertop

You can also make a slurry and coat it before grinding it to fill the holes and trowel marks.

This

You'll be amazed at how well you can fill all those bugholes. Mix up some portland and latex additive and work it into the holes. I found it worked best to do it when you are at about 800 grit - set your grinder on slow, and use the pad to work the slurry into all the holes. Then go back over with 800 once it dries. Found that on some concrete countertop website and it worked a treat

[RichC]

Re: Improving 'floated' finish on concrete countertop

Thanks guys but I'm going to redo it. Just not happy with it and I'll be looking at it for a long time. It's 50mm at the thinnest to about 70mm in places with steel mesh about 3mm thick inside. Will I be able to cut that with my grinder and diamond blade or should I rent a consaw?