Improving finish to concrete

Is there anything I can do to improve the finish of set concrete. I want a smooth finish and I have got that for most of the surface but in a few places it is acceptable but could do with being smoother. Concrete is still fresh so it is not as hard as it will be in the hours and days to come. It's a window sill.

VisionSet wrote:
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Strong sand & cement? - I'd use fine building sand rather than grit sand, although I wouldn't bother with it yet as it will probably need facing up once the box comes off.
We always used to use granno instead of concrete for sills, it's much finer and packs down better and leaves a better finish.

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I used 20mm agregate for the bulk and finsihed with 4:1 grit and cement and left the whole lot to go off together. But it's what I had for the job and it was apparant that the the 2 mixes were pointless and as you say the key factor is the finest sand you have. I'll probably leave it as it is, I was hoping that I could wetordry the odd patch or some similar approach. I think this is a skill as involved as plastering. The latter I'm pretty good at but then there is more opportunity to get good at it. It's going to be along time before my cement based skills are on par.

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Mike, Possibly no help to you now, but if you do have to do another this may help. I learned this from an old Frenchman when setting in a new window in a mates house (in France). We used medium agregate 10-20mm with reinforcing mesh in a strong box mould with a strip of half round wood to create a drip rail. We made the concrete fairly dry and tamped it in well. This always raises a little water onto the topsurface. Rather than sweep this away, the old boy sprinkled neat cement over the surface until the water was soaked up and then trowelled the near dry surface to a smooth finish. Easy when you know how.
Bob