Terrazzo is having a moment again and most people who ask us for it do not want terrazzo. They want the look: stone chips scattered through a calm ground, ground flat and polished, in a colour they chose. What they do not want is a fifteen millimetre poured bed, brass divider strips, a week of wet grinding and a floor that cannot go over the one they have. Micro-Stone and Micro-Granite are how we give them the first without the second.
What they are
Both are microcement with stone in it. The build-up underneath is the one we use for every microcement floor or wall: primer for the substrate, base coats with mesh for crack resistance, about three millimetres in all. The difference is in the top coat. On a plain microcement floor the top coat is trowelled, sanded and sealed. On a stone finish it is trowelled, rolled open and then, while it is still wet, stone is broadcast into it by hand and rolled in. Once it has cured the surface is sanded back until the stone shows, pore-filled and sealed.
Micro-Stone uses a blend of stone flakes, large and fine together. The large flakes set the scatter and the fine stone fills the ground between them, so the finished surface is dense and even rather than spotty. There are eleven standard large-flake blends and eighteen fine-stone blends and they can be mixed, over a ground pigmented to any colour in our range or to a paint reference.
Micro-Granite uses granite chips instead, in one of two ways. Full coverage broadcasts the chips until the top coat is covered, then sands lightly back to a dense, even face that reads most like terrazzo. Part coverage, which is what our sample board shows, puts a rustic coat down first for depth and then sprinkles the chips lightly into the final coat as it is trowelled, for a loose salt-and-pepper fleck with plenty of ground showing between.
Why the ground colour matters more than the stone
On a plain microcement floor the colour is the colour. On a stone finish the stone keeps its own colour whatever you do, so the ground underneath is doing the work. Pale stone on a dark ground reads as a night sky; the same stone on a pale ground almost disappears. Dark flake on Chalk is crisp and graphic; dark flake on Smoke is quiet and warm. We have had clients bring us a terrazzo photograph, choose the flake blend that matched it exactly and then find that the ground colour they had in mind made it a different floor altogether. This is why we do not quote a stone finish from a swatch. The combination is made up as a panel, in your light, before anything is ordered.
Where they go
Anywhere the microcement system goes, because that is what they are. Floors first: the method was written for floors and it is where the terrazzo reading is strongest. Then worktops and islands, where full-coverage Micro-Granite has the density to take real use. Stairs, where the stone gives a little texture underfoot. Wet rooms and bathroom floors, with the wet-area sealer route. And walls, where part-coverage Micro-Granite gives stone character without the weight of a full terrazzo field. The rules are the ones that apply to any microcement: a sound substrate, movement joints carried through to the surface and a full commissioning cycle on underfloor heating before we start.
Sealing is half the finish
After sanding, a stone surface is open. The flakes sit flush but there are pores between them and a floor left like that would hold dirt. So the first sealer is a pore-filler: a trowelled filler in dry rooms, sanded back so it stays only in the pores and does not leave a plastic skin on the stone, or a thickened wet-area sealer where there is water. Then one or two coats of a two-part polyurethane go on top, which is what takes the wear and sets the sheen. The top sealer can be polished to a diamond finish the following day if you want a gloss. A new floor is covered with breathable board for a fortnight before it goes into use; tape never goes on the surface.
What to expect from the process
The broadcast stage is quick and it has to be. The top coat is applied by one person and the stone by another, a few metres behind, because top coat that has skinned over before the stone lands will not hold it. Windows are shaded and a slab that is too warm waits for a cooler day. Sanding does not start until a fingernail pressed into the surface leaves no mark, which in cold weather or after a late-afternoon application means an extra day. None of this is difficult but all of it is unforgiving, which is why we do not rush it and why we say so when a programme asks us to.
Honest limits
A stone finish is a little harder to wipe down than a flat sealed microcement, because there is texture for dirt to sit in. The pore-filler is doing more work than most people realise. Repairs are done in place with the same mix and blend well on a floor with a scatter, less well on a dense full-coverage field, where a patch can read as a slightly different density of stone. And like any microcement it is not vapour-open, so it is the wrong finish for a wall that must breathe. For that there is lime or clay.
The stone finishes page has the three systems side by side, with the sample panels. The visualiser will put Micro-Stone or Micro-Granite on every surface of a kitchen. If you have a terrazzo reference, send it with the drawings and we will make the panel.