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      Ottawa Masonry Services: About Cement & Concrete Colour Dyes:

 

Cement Pigments & Colour:

Colour is affected by three variables: the observer, the object, and light.

The Observer:
Each person is different, and seeing colour is a sensation that varies from person to person. Some people are colour blind, some have difficulties with a colour range, like red or green, some don't even know they have different colour abilities. Colour sensation is provided by the X gene, and so while women have two X genes and generally less colour problems, men only have one X gene (and a Y gene) so they tend to have a higher incidence of colour problems.

Macular degeneration makes the lense of the eye become yellow and cloud the eye, so that the amount of light reaching the back is limited, affecting colour perception. This condition is generally affected by age.

Other elements can play tricks on the eyes too. Colour averaging is when a person looks at an object and their eyes make colours appear where they are not, or blend colours. Looking at a grid of black blocks with white lines separating them and white dots at each intersection tends to produce this effect. Retinal fatigue can arise from looking too long at a colour, particularly a strong colour. Colours surrounding a colour can affect perception of it too - so that the same colour can appear different with varied backgrounds, or slightly different colours can appear the same for the same reason.

The Light:
We all have seen the impact of different lights, from flourescent to incandescent to sunshine to shaded and coloured light. A prism can break white light into component colours, so it too can play a difference, with outdoor light changing from day to day.

The Object:
The surface of an object will affect how light is reflected, so a smooth surface will reflect differently than a rocked surface. Similarly, a finely structure grey butterfly wing can appear to have colour as some wavelengths are absorbed. One's angle of viewing can affect how something looks too, so that two people standing near each other can see different results. In another example, the head of a beer is still made of beer and hence the same colour of liquid, but it appears white as it reflects light differently.

Cement and Colour:
Cement can be affected by the quality of the water, especially is well water is used with its generally higher salt content.

Cement colour can be affected by curing conditions, such as extreme heat where flashing occurs when the water evaporates instead of curing, or when calcium hydroxide forms in the curing process, or if conditions are too cold. Of course the aggregates used, the colour of the cement itself (which can vary from manufacturer to manufacturer), and the amount of pigment used, affect colour too.

 

 

Surface colouring techniques
- excluding acid stain, are applied to cement or concrete topically to add color or shift an existing colour.

Solvents vs Dyes:
Dyes applied with solvents result in one color throughout, while acid stain chemically reacts to present a range of tones of the colour,

Dyes are in their natural, concentrated, powder state or are blended with either alcohol or solvents including water. The solutions react differently: a water-based solution evaporates slowly and so pooling and puddling can occur - even desirably. Acetone dries very fast therefore the color will 'flash off,' without pooling or puddling. Other solvents are in between.

Fading Factors:
Sunlight and the salts used in Canadian winters may fade cement colours. Sealers can be used to address this somewhat. Weathering exposes aggregate which can affect perceived colour.

Topical Colour Prep:
Thoroughly clean the surface. This can be done with a non-residue cleaner and a stiff bristle brush. Avoid wire bristles, since these can damage the surface of the concrete, making acid stains take unevenly. Use a degreaser to remove grease spots and scrub until the spots are gone. Adhesives and paint spots can be effectively removed with paint thinner.

After using these cleaning substances, it is important to rinse the area thoroughly with a garden hose. You can also use a power washer to make sure every speck of debris and dirt is removed before the staining process commences. Once your concrete surface is completely clean, allow it to dry thoroughly before staining. This may take a day or two, depending on the weather conditions.

Concrete stain is similar to wood stain but can actually highlight and intensify the variations found in the concrete. This includes natural as well as man-made blemishes and markings.

Acid stains react differently to each type of surface to which they are applied - so it is imperative that a sample is done on the actual concrete or surface that is going to receive the treatment.

Potential Problem:
Too little product won't give complete coverage, nor will it etch the surface sufficiently to deeply deposit the color. Too much product on the other hand can cause unwanted puddling and pooling and over react the areas where it has pooled on the surface. Then there is the scrubbing method. If scrubbing isn't done with a natural flow and pattern, mop lines and obvious swirls may appear.

Once the concrete is sufficiently dry a sealant of coating should be applied.

Even if you hire the best acid stain concrete contractor in your area, their abilities will depend on the surface on which you give them to work with. It may not be possible to completely hide and blend-in the color with a badly stained and damaged concrete slab.