Levels of Stone Exposure

Levels of exposure

Nil –Min exposure is a finish where you can see little to no stones showing through the concrete surface. This type of finish is particularly hard to achieve. It is not hard for us to achieve, but it is hard for your concreter to achieve because it requires the concrete to be poured to very stringent specifications, ensuring there are no undulations throughout the floor as this can affect the overall outcome of the finish. The slab needs to be poured perfectly flat so that we can polish it without exposing any stones.

So if you want this type of finish you need to let you concreter know before he pours the slab. If you have an existing floor that you want finished to a NIL/minimum we will do our very best, but if the slab isn’t 100% flat and there are so high and low spots it just means that you may have some small amount of aggregate showing through. This is why we call it a NIL/minimum finish instead of just NIL. The most important thing to remember is that it is up to the concreter to achieve a high standard pour in order for us to polish a high standard floor.

Minimal/Random – is a finish where you can see some areas of no stone exposure and other areas where some stones are showing through. This is most often used for budget projects as it is a more economical option and for those who really like that industrial look as well as garages, restaurants and outdoor areas. In order to achieve this look we grind the floor once which usually removes the top 1 – 3mm from the surface. This finish is referred to as the salt and pepper look, given the possible uneven exposure of stone.

Full Exposure – is probably the most popular finish and it as the names suggests shows the stones in full. It looks like the stones have been cut in half and provided the concrete has been poured evenly will usually have no areas without stone exposure. To achieve this decorative look does take time and is a more labour intensive process, and therefore is a little more expensive. Generally it requires grinding 2 – 3 times over the entire floor to achieve the desired result. Generally, we grind down 5-6 mm depending on the hardness of the slab. The full exposure finish is favored for use in homes and showrooms.

Full exposure – 2-3 Grinds


Minimum/Random exposure – Single Grind


Nil exposure


Minimal/Random – This is often referred to in the industry as a salt and pepper look. It is where we grind the top 1-3mm of the surface usually going over the entire floor just once. There is often no stone exposure in some areas, and other areas have a little or a lot depending on how the slab was poured. This is often used for the industrial look, or for garages, restaurants, outdoor areas etc. and is a more cost effective option.


Full Exposure – This process is more labour intensive as we have to grind over the floor usually 2-3 times to get all the stone showing. As a general rule we grind down 4-5mm depending on the slab. This is a more decorative look and is often used in homes and showrooms.