Where house painting is concerned, one of the prime objectives is to ensure that the paint remains bonded to its substrate and that it retains its essential properties for as long as possible. Selection of the right paint materials is absolutely crucial in achieving this objective.
The primary function of architectural paint is to protect metals, wood, and other materials against corrosion and decay. In order to better differentiate between different grades of paint, it is necessary to have at least some understanding of what raw materials go into every can of paint.
I hope that by reading this you will learn how to make a better decision as to what paint materials should be used to protect, what is perhaps, the biggest investment you will ever own.
All paints consist of four basic components: pigments, binders, liquids and additives. Each of these ingredients has a specific effect on the paint's performance.
- Pigments are finely ground materials that give the paint its color and hiding capacity. The most common white pigment in paint today is titanium dioxide.
- The binder holds pigment particles together. As the paint dries, the binder binds pigment particles into a continuous film as well as binding them to the painted surface. The type and the amount of binder also has a big effect on the paint's durability, stain resistance and color retention.
Alkyd (chemical compound made with vegetable oils) is the binder used in most solvent-based paints made today. The two most common binders in water-based paints are "acrylic" and "vinyl acrylic". 100% acrylics provide better overall performance than vinyl acrylics.
- Liquid's main role is to keep pigments in an easy-to-paint fluid state. The liquids evaporate and what remains is a continuous film of pigment and binder. In oil-based paints, the most frequently used liquid is mineral spirits. In latex paints, the main liquid is water.
- Additives are ingredients used to improve the performance of paint in some way. For example, preservatives keep the paint from spoiling in storage; mildewcides keep mildew from growing on the surface of the paint.
By varying the amounts and types of pigments, binders, liquids and additives, the paint manufacturers can create a large variety of paints and, as they substitute the lower quality/cost ingredient for higher ones, they can manipulate their costs and profits. For example, the term "pigment" is also used to refer to extenders, which are materials such as clay, mica and silica that, among their other properties, add bulk to the paint without significantly adding to its cost.
The two main indicators of the paint's quality are its volume of solids and the titanium dioxide content. This information can generally be found on a product's Technical Data Sheet (TDS) and Material Safety Data Sheet (MSDS), which are generally available to anyone right where the paint is sold.
- Volume of Solids - also sometimes referred to as Solids by Volume
The higher quality paint will have a higher percentage of binders and pigments - collectively called solids - and a smaller percentage of liquids than lower quality paint.
Higher percentage of solids by volume will translate into a thicker and stronger paint film, greater hiding ability and better protection of the painted surface. Lower grade latex paints will typically contain about 20-30% solids by volume and 70-80% water, while higher quality latex paints will generally be 35-50% solids.
- Titanium Dioxide Content
This ingredient gives white or light-colored paint its ability to cover darker colored surfaces in less number of coats.
Quality white latex paint will usually contain 20-25% of titanium dioxide. Lower quality paints contain more extenders than higher grade paints. Because of this, they will have less hiding power, even though their solid content may be high.
Yes, higher quality paint will typically cost more. On the other hand, the lesser cost, lower quality paint may not be a bargain at all, particularly if its service life is much less that of a higher quality and more expensive paint.
However, it is important to note that higher priced paint is not a guarantee of higher quality. Sometimes the higher price will simply represent higher marketing and transportation costs. So, as with anything else, there is no substitute for understanding!