Walls with the look of microcement in the province of Málaga. Two jobs that are nothing alike are offered under that name: a paint that imitates the finish, and a coating of several trowelled layers with varnish. On a wall that is there to be looked at, paint can be enough. On a floor or in a shower, it is not. Here is how to tell which one you need.
The light, the test patch on the wall and how many walls to treat apply to any decorative finish, and they are explained under decorative painting.
The question is not which colour, but which of the two. That decides where it can go, how long it takes and how much it costs.
A seamless coating, not a paint. The one in the data sheet we have read comes in two components that are mixed on site; it is applied by trowel, layer after layer and very thin, each layer is sanded once it has dried and the whole thing is finished with two coats of varnish. It is stated for vertical and horizontal surfaces, indoors and out, which is why it can also go on a floor.
A decorative paint that reproduces the look: the clouds of tone, the trowel marks, that mineral grey. On a vertical wall that is there to be looked at, it can look the same with far less work. What it does not have is the system underneath and on top, and that is why you cannot ask the same of it.
Inside a microcement, from the bottom up
Six steps on the wall, five on the floor
On the wall
Four trowelled layers and the varnish
On the floor
Three layers, with coarser grain on top
Between one layer and the next, 12 to 24 hours of drying and a sanding. This is the recipe from one particular data sheet; another system will have its own, and its data sheet is what counts. The drawing does not show the real thicknesses.
For a seamless trowelled finish, but with sheen and depth, the benchmark is Venetian plaster.
The living-room wall behind the sofa, the headboard, the front of an entrance hall, a section of wall in an office or shop. Vertical surfaces that are seen a lot, touched little and do not get wet. There the eye cannot tell what system is underneath, and paying for it means paying for a system nobody is going to use.
The floor, the shower tray, the shower wall, a worktop, a built-in bench. Places that are walked on, get wet every day or are scraped by objects. There the look is not enough: you need a coating whose data sheet states it is suitable for that use, with its layers and its varnish. An effect paint is not one, unless its data sheet says otherwise: ask for it.
Five conditions from a current microcement data sheet. They help explain why it is building work and not a coat of paint.
The data sheet asks for it without qualification: all surfaces level and consolidated, clean, dry and free of dust, grease, soap and paint in poor condition. With layers that, depending on the grain, must not exceed 0.3 to 0.8 mm each, there is no thickness to hide a crooked wall: it copies it.
Over tiles, the joints are filled first with a specific product and left to dry for 24 hours before priming. And the building’s expansion joints are always respected: the data sheet promises a seamless, crack-free coating with that condition in brackets.
The data sheet asks for the trowel to be held at about 45°. A layer that is too thin can “burn” and leave dark marks on light colours; one that is too thick slows drying and can bring blisters or cracks. It is craft, and it is the reason the same product turns out differently in two pairs of hands.
Each layer has to dry for between 12 and 24 hours before the next, and the data sheet expressly says not to apply wet on wet. After that, at least 24 more hours before the varnish. And the sealed system reaches its full performance a week after the last coat of varnish.
The data sheet recommends applying it between 15 and 25 °C with relative humidity no higher than 50%, and warns that temperature and humidity change the drying time between layers. On the coast there are days when that humidity is not met, and it is better to know before setting the dates than to find out with a layer that will not dry.
With an effect paint on a living-room wall, almost none of this applies. That is why, where paint is enough, it is the sensible choice.
“Microcement effect” is used for both the paint and the system. To compare, each offer must specify the product, the number of layers, the varnish and how many coats of it. A paint and a microcement do not cost the same because they are not the same job.
A real microcement means several days of layers, sanding and waiting, and another week until the varnish gives all it can. In a bathroom or kitchen used every day, that needs organising beforehand. With an effect paint on a living-room wall, the problem does not exist.
The system in the data sheet is very closed to water and fairly closed to vapour, and for a damp surface it calls for a different, barrier primer. If the wall has a patch that comes and goes, find out where it is coming from before covering it with anything.
For a bathroom wall that does not get the water from the shower, it may be, if its data sheet allows it in damp conditions. For the shower area, the floor or around the basin, no: there you need a coating whose data sheet allows that use, or to stay with tiles.
The data sheet we have read provides for it: over tiles, the joints are filled first with a specific product, left to dry for 24 hours, primed, and then the layers go on. If all you want is to change the colour of the tiles without building work, that is something else, and it has its own article.
The data sheet sells it as a seamless, crack-free coating, on one condition: always respect the expansion joints. And it warns that layers that are too thick can bring blisters or cracks. What is underneath counts too: it has to be level and firm.
We do not recommend it, unless that paint’s data sheet states it is suitable for floors. The microcement in the data sheet we have read has its own recipe for floors, with a different grain in the finishing layer, and its varnish.
It depends on which of the two it is, and the difference is large: an effect paint is a painter’s job; a microcement is several trowelled layers, sanding and varnish, on different days. Without seeing the wall and knowing where it is going, we do not give a price per metre.
To change the colour of your tiles without building work: paint the tiles instead of replacing them.
Send us a photo of the wall or floor and tell us how it is used: whether it is walked on, gets wet or gets touched. With that we can tell you whether effect paint is enough or the full system is needed, and we plan it with a sample.