PAINTING & SURFACE PREPARATION – TIPS & TRICKS
There are a number of things to take into consideration when painting walls and floors, both internal and external. The successful adhesion of paint to a surface depends upon how well prepared the surface is and whether it has been cleaned sufficiently. Too often paint does not leave the finish required and a build of of layers can occur, as mistake upon mistake is layered on. To avoid this, prepare the surface, judge the environment and use the right products. Paint is not simply paint, and this is why at many stores, including Rawlins Paints, there are thousands of different paints for hundreds of different surfaces, environments.
Where to start is the first question. Here:
1. AIR AND SURFACE TEMPERATURE
These two parameters affect the physical properties of the products during preparation and application. For all products, these criteria have an influence on the touch dry time and on complete drying and overcoating times. At low temperatures drying times will be slower.
This also applies to properties such as viscosity, rate and nature of dilution. At high temperatures viscosity will decrease and at low temperatures it will increase. It is, therefore, important to store the products in areas in which the temperature will be close to the optimum conditions for use and to use a suitable thinner.
Some water in the form of invisible vapour is intermixed with the air throughout the atmosphere. It is the condensation of this vapour which gives rise to clouds, rain, snow, dew, frost, and fog. There is a limit to how much water vapour the air can hold and this limit varies with temperature. When the air contains the maximum amount of vapour possible for a particular temperature, the air is said to be saturated. Warm air can hold more vapour than cold air. In general the air is not saturated, containing only a fraction of the possible water vapour.
3. DEW POINT
The dew point indicates the amount of moisture in the air. The higher the dew point, the higher the moisture content of the air at a given temperature. Dew point temperature is defined as the temperature to which the air would have to cool in order to reach saturation. A state of saturation exists when the air is holding the maximum amount of water vapour possible at the existing temperature and pressure. Condensation of water vapour begins when the temperature of air is lowered to its dew point and beyond. The dew point, like other measures of humidity, can be calculated from readings taken by a hygrometer.
Condensation is the process whereby water vapour in the atmosphere is returned to its original liquid state thus causing a surface to become wet. This is a problem which tends to occur particularly at the start or end of a day, especially outside. Condensation is not a matter of one particular temperature but of a difference between the two. Condensation of water vapour occurs when the temperature of air is lowered to its dew point. At this point a problem will occur when you paint a surface.
The above factors affect painting projects on a daily basis but each parameter can be measured before painting starts to ensure conditions are suitable for the chosen paint or coating. Various testing equipment can be used (see here: https://www.rawlinspaints.com/testing-equipment), however if in doubt, contact our Technical Services on 0113 2455450 or [email protected].