Casting a concrete countertop - pictures, questions..

[hydrolift]

After all, I think the absolute best is to use a diamond sander to achieve a glossy surface through grinding that requires no maintenance. But, no matter how I looked, I couldn't find any except for large floor sanding machines, which are both expensive and cumbersome.

LiMa

There's a Makita that might work:

http://katalog.essve.se/webspeed/ka...t_bid=V70&dokid=wc63672&katnr=2&katsektnr=324

But maybe the finish will be too coarse with that one?
Quoting "For effective grinding of flash, irregularities, and edges".

 

[LiMa]

There is a Makita that might work:

[link]

But maybe it gives too rough a finish?
Quoting "For effective grinding of flash, irregularities, and edges."

Definitely worth a try!

 

[Fjordlund]

Do you do anything to round off the edges? Either in the mold or in the post-processing? I guess it becomes more sensitive the sharper the edge is. Or?

 

[Apprentice]

Fjordlund, draw a silicone bead in the mold and you'll get a slightly rounded edge.

 

[LiMa]

Fjordlund, draw a silicone string in the mold to get a slightly rounded edge.

I made a small chamfer with a plastic spatula so that I didn't get too much rounding. Then you sand the edge, first very gently and then when it has "stabilized" you can go harder.

 

[wireless2000]

Where can one find this water glass material?

By the way, I have figured out where the right soap is sold (the one mentioned in Finja's brochure), www.essemess.se

The surface as it is now on my slab is too rough, so I will probably redo it. It seems that diamond paper + water glass is what is needed to achieve the shiny surface I'm aiming for.

 

[anaitis]

Where can you find this sodium silicate material?

By the way, I've figured out where the right soap is sold (the one mentioned in Finja's brochure), www.essemess.se

The surface on my board as it is now is too rough, so I will probably redo it. It seems that diamond paper + sodium silicate is what you need to get the glossy surface I'm after.

You can buy sodium silicate at the paint store!

 

[wireless2000]

Now bought vattenglas (thanks anaitis). How to apply? Nothing is written on it and the man in the store didn't have a clue.

 

[anaitis]

Now bought vattenglas (thanks anaitis). How to apply? There's no information on it and the man in the shop had no clue

Brush, roller or (if it's a horizontal surface) simply pour it on and spread it out with a window squeegee.

 

[alexwidell]

problem...
I'm making three slabs.. Made two of them, the island and a filler piece.
Now I've made the one with holes for ho etc.
Reinforced it and all that, but it cracked at the thin spots around the ho when we were lifting it...
Any tips?

 

[LiMa]

problem... I am making three slabs... Have made two of them, the island and a spacer piece. Now I made the one with the hole for the sink, etc. Reinforced and all that, but it cracked in the thin areas around the sink when we tried to lift it... Any tips?

First of all, the mold must be placed directly on a completely flat surface; I cast on the basement floor. When you then need to move it, do it on the edge, pressing the slab in the mold with clamps or similar. When there are such weak/narrow parts, they are extremely fragile to side movements. So brace it before moving...

Good luck!

/LiMa

 

[anaitis]

problem...
I’m making three slabs.. Made two of them, the island and one filler piece.
Now I made the one with holes for the ho etc.
Reinforced and everything, but it cracked at the thin spots around the ho when we tried to lift it...
Tips?

I also think the reason is that the slab flexes too much.
I could think of two methods to reinforce locally at the cutout for the ho:

1 Add a bit more reinforcement locally, diagonally at the corners. Rebar should work, otherwise thick steel wire.

2 Make an additional reinforcement after casting before you remove the form. Sort of like thickenings around the cutout, not so close that it interferes with the ho’s mounting. Can be done with concrete or something else. You can actually cast these reinforcements separately and then glue them on with epoxy glue. The latter method has been used to attach frames in concrete boats!

 

[anaitis]

Also check how Finja reinforced here:

 

[alexwidell]

Hello,
I had some consultation yesterday, and we decided to try oiling first before I make a new one.
Said and done, the cracks are almost "as good as gone"...
I'll have to live with some small shadows, but isn't that the charm of concrete? Otherwise, I could have bought compact laminate

 

[LiMa]

Looks good! I think the wall is a bit blotchy but maybe it's supposed to be like that?!?