Our next blog installment is all about colour and finish look and feel. One of the advantages of concrete is that is can be made to look like anything you want. Since it xeroxes well to anything it is cast against it will pick up the smallest details. So if we want it to have a tight clean modern look we can cast on a polished clean surface like glass or plexiglass and get a mirror like finish. Or we can cast against wood and get a rustic wood finish. We usually cast on plastic laminate or on melamine which has a slight texture which can be honed or ground off in the processing stages. Other ways to remove the cream layer are acid washing, sanding, or adding retarders to the face of the mold prior to pouring. Rubber molds can be used to create rock edges or wood trim can be used to make interesting relief on the edges. It really is endless.
Colour is another endless option for concrete. Any color in the rainbow… or the Benjamine Moore fan deck can be achieved using simple iron oxides, liquid colours or external methods. Since we start with white Portland cement it acts as a blank canvas to the color. The color goes throughout the piece and the sealer enhances the colour. If we want a simple concrete colour we will use a mix of white and gray Portland cement to achieve the desired shade of grey chosen by the client.
Sand and stone also affect the finished colour so selection of these also are taken into account when coming up with the finished product. White sands are used in light colour tops and darker sand in darker tops. The sands give the concrete a salt n pepper look. Recycled glass can be used instead of sand to give a different look to the piece. Different sized glass, single or multiple colours, broadcasting or wet casting all have different looks. The glass can be used as accents or be wet cast throughout the piece.
External methods can also be used such as acid staining, acrylics , etching, stencils, to add colour to the surface of the concrete. Acid staining reacts with the concrete to stain the surface and needs to be neutralized prior to sealing. Acrylics can be used like acid stains or used with fine detail to create images on the piece. Logos, images and lettering can also be added to the concrete surface. Again…it is endless!!
Different techniques can be used to give the surface a more stone look. Mixing different colours of concrete just prior pouring can give the surface a marbled look. Veining can be achieved using different methods and the surface can also be pitted using baking soda or other additives. Hand placing, dry pack, high spray, can also give a natural texture to the surface. These surfaces are not used for counters and are more for wall panels, fire place surrounds and furniture pieces.