Hello!
My partner and I were thinking of making our own concrete windowsills after realizing that there are no decent/stylish options available at the local hardware stores.
We found several guides on how to do it and thought it couldn’t be that hard. However, since we live in an apartment in Gothenburg, it makes things a bit more complicated.
To avoid having 4 large molds sitting in the living room, we thought we’d head to the countryside to cast them. The plan was to go there for a weekend to do all the casting, but we quickly realized that all the guides said you need to "water" the concrete generously over several days, which we can’t do if we're only there for the weekend.
Is there a limit to how long you MUST "water" the concrete? Could you water it thoroughly for one day and then leave it in the countryside for a few weeks to pick up at a later date?
What would happen if you water it for too short a time, or if you leave the concrete in their molds for a bit longer (say 2-3 weeks)?
Thankful for any input!
/Nichlas
My partner and I were thinking of making our own concrete windowsills after realizing that there are no decent/stylish options available at the local hardware stores.
We found several guides on how to do it and thought it couldn’t be that hard. However, since we live in an apartment in Gothenburg, it makes things a bit more complicated.
To avoid having 4 large molds sitting in the living room, we thought we’d head to the countryside to cast them. The plan was to go there for a weekend to do all the casting, but we quickly realized that all the guides said you need to "water" the concrete generously over several days, which we can’t do if we're only there for the weekend.
Is there a limit to how long you MUST "water" the concrete? Could you water it thoroughly for one day and then leave it in the countryside for a few weeks to pick up at a later date?
What would happen if you water it for too short a time, or if you leave the concrete in their molds for a bit longer (say 2-3 weeks)?
Thankful for any input!
/Nichlas
Cracking is the risk.
If you cast on Saturday, and water until you go home on Sunday and have the benches wrapped in construction plastic, it should probably be fine.
The construction plastic prevents evaporation so quickly.
If you cast on Saturday, and water until you go home on Sunday and have the benches wrapped in construction plastic, it should probably be fine.
The construction plastic prevents evaporation so quickly.
What about transporting them while they are setting? If we could drive them home (in the molds) on Sunday to possibly "water" them one more day at home, is that better or worse? (considering the transport)
What about the temperature, by the way? Where we were thinking of keeping them, it's perhaps 12-14 degrees now, is that too cold?
Thanks for the quick responses!
What about the temperature, by the way? Where we were thinking of keeping them, it's perhaps 12-14 degrees now, is that too cold?
Thanks for the quick responses!
It sets quite fast; I cast some curbstones last summer. Did three castings per day in each mold. If you cast in the morning, there shouldn't be any problems taking them home (in the mold) in the afternoon.Sndr said:
My own experience is that it's better to let the concrete sit in the mold longer than watering it.
During the first days, the concrete is weak and will crack if moved.
Pour on Saturday and make sure to keep it moist until you leave. Then water it extra and cover it properly with plastic.
The warmth might actually be beneficial as it prevents the water from evaporating too quickly.
But otherwise, there's no problem with pouring in the living room, it should be less hassle overall if you can endure a week with reduced floor space.
During the first days, the concrete is weak and will crack if moved.
Pour on Saturday and make sure to keep it moist until you leave. Then water it extra and cover it properly with plastic.
The warmth might actually be beneficial as it prevents the water from evaporating too quickly.
But otherwise, there's no problem with pouring in the living room, it should be less hassle overall if you can endure a week with reduced floor space.
Feeling much more confident for my casting session, and it will be casting on Saturday and then heading home on Sunday evening, with the concrete in the molds. Then it's waiting for a day in the living room with a little more watering.
Thanks for all the help!
Thanks for all the help!
In my limited experience, I don't think you should lay plastic directly on the mold. The risk is that water will seep into the gap between the concrete and the mold, causing discoloration in the concrete. Especially if you have to lift the plastic to water, as condensation water will run down onto the concrete in puddles. What you need is a water reservoir in the form of a towel or blanket that you dampen—not so much that it drips—and then lay the plastic on top of that. This way, you don't need to water as the reservoir keeps the concrete moist and handles the condensation. If you want it to cure faster, you can use a heating blanket.
12-14 degrees is perfect. The risk on the lower end of the temperature scale is frost. The risk on the upper end is that it dries before it's finished burning. Between 5-20 works fine. Lower (within the range) = slower = betterSndr said: