Some common traits of good sandfinish are an even colour of the render. An even sand texture across the face of the render and a sealed hard face.
You are using a wooden or plastic float to compact the surface and bring the fines to the surface while maintaining an even water content in face of the render.
This is a very coarse concrete sand down in Narrogin. You can see the raw float coat at the bottom and the actions of using the float as you spray a fine water mist over the render. The amount of water to the face differs during the year. The top wet face is not ready for the sponge as it needs the rocks pushed further into the mortar and a more compacted surface.
This is getting close, probably another pass. You can see how the surface is becoming smoother.
You can see the sponged texture in the face coming up to the floated render. With this type of rough plasterers sand if the face is too wet you can create what is known as Mexican swirls which has texture lines sponged into it
Look at the top of the photo
The object of bringing the fines to the surface with the float is to "close" the face and create a thin cement shell over the face of render. The sponge finishes the face off even further closing the face and creating the sand texture.
A series of photos taken when the midday architect shows the grains of sand as the texture coat. If there were two plasterers applying the sponge finish to this render then there is a good chance there could be two different texture finishes.
It is the plasterers sense of touch that will determine the flatness of the floating and the evenness of the texture. The cement shell serves two things. One is the very hard surface and the water repellent properties of cement. For example if the wall is a week old and 25 mm of rain discharges out of the down pipe pops on Friday it should be dry by the next day
If the render is holding water for a number of days then the surface is open and porous. The painter can tell the difference. Also the render should meet the concrete footing creating a seal so to speak to stop the moisture getting behind render and paint, also applies to texture coat.
You can see the thin coat of cement over the surface of the render. This is a very old outhouse and the bricks are literally a lost cause in the rising damp scenario. The moisture has penetrated the outside face of the brick and is working its way horizontally through the brick to the under side of the cement surface of a single brick wall.
The photo was taken 12 months after and entailed brushing the loose face off. Flaky paint also is an indication of a damp problem.
A hand sponge is used to create the sand texture and seal the face. To achieve the consistent texture you have to motion the sponge in either a circular or figure of 8 direction. Changing between the two actions half way along the wall will change the finish. Also try not to create lines in the surface, this can be problem with coarser sand and may require more float work. This a very coarse sand from Neaves rd.
The consistency of the final dried cement colour comes from an even water content in the floated surface. If water is required it is sprayed onto the wall not the sponge. The sponge should be dry when applied to the wall. We use very little force on the sponge whilst working it. Just like texture coat if there are two of you it is easy, with one floating and the other following behind with the sponge. The water content and hardness will be consistent in the face of the float for the sponge.
