Processing concrete during curing?

[LukasK]

I was thinking of casting lamp fixtures for garden lighting in concrete. To facilitate form-building (15 fixtures), I wonder if I can cast 15 cylinders and then work on them after a while to create the cavities and patterns required/desired. Is this a good idea? When during curing is it best to do this then? By working, I mean nothing more advanced than using a Morakniv to carve out where needed. I should add that the cavities are quite small in relation to the concrete volume (approximately 10x10 cm cylinder should have a conical hole going to the middle from the side with the largest opening at maybe 3-4 cm).

 

[Tompafix]

I'm planning to cast lamp fixtures for garden lighting in concrete. To facilitate mold building (15 fixtures), I'm wondering if I can cast 15 cylinders and then work on them after a while to create the required/desired cavities and patterns. Is this a good idea? When during the curing process is it best to do this, if at all? By work on I mean nothing more advanced than using a Mora knife to scoop out where needed. I can add that the cavities are quite small in relation to the concrete volume (about a 10x10 cm cylinder should have a conical hole into the middle from the side with the largest opening at maybe 3-4 cm).

I've cast some concrete elements in a factory.
We used styrofoam, wood, or rubber to make cavities, etc. These need to be lubricated so they can be easily removed.
If you're going to carve out these holes manually.
Can you reach the places when the mold is still in place?

 

[LukasK]

Have cast some concrete elements in the factory.
We used Styrofoam, wood or rubber to create cavities, etc. These, however, need to be greased in so that they can be easily removed.
If you're going to manually carve out these holes.
Can you reach the places when the form is still in place?

Will probably need to remove the form, unfortunately, but I thought it shouldn't be a problem if you cast with what's called soil-moist concrete? Alternatively, if you wait until the concrete has hardened enough for form removal (but still can be carved)?

 

[cpalm]

Test it! It can't get worse than going wrong. 🙂
But in principle, it should go well, I think. It's like demolition and smoothing; you have to time the exact right consistency. But easier said than done if you ask me.

It's probably best to include it from the start. The surface will be nicer too.