Zinc oxide is a pigment having colour:
Try it first: pick an option, then read the explanation.
The Role of Base Pigments
In paint, the "base" is the primary pigment that forms the foundation of the paint film. It provides the bulk of the hiding power (opacity) and contributes to the paint's durability. Most bases are white pigments, which serve two purposes: they can be used alone to create white paint, or they can be tinted with other coloring pigments to create a wide range of lighter shades.
Detailed Analysis of the Options
(a) Blue, (b) Red, (c) Yellow
Pigment Type: Coloring Pigments.
Analysis: These are colors provided by specific coloring pigments, not base pigments. For example:
- Blue: Prussian blue, Ultramarine, Cobalt oxide.
- Red: Red lead, Iron oxide (rust).
- Yellow: Yellow ochre, Chrome yellow.
(d) White
Pigment Type: Base Pigment.
Analysis: This is the correct answer. Zinc oxide is a fine, synthetic powder that is brilliant white in color. It is a key base material in modern paints for several reasons:
- Color & Opacity: It provides a clean white color and excellent hiding power.
- Non-Poisonous: Unlike the traditional white lead, zinc oxide is non-toxic, making it much safer for general use.
- Chemical Resistance: It is unaffected by sulfur compounds in the atmosphere, which can cause paints made with white lead to darken or yellow over time.
- UV Resistance: It helps to protect the paint's binder from degradation by sunlight.
Common Pigments and Their Colors
| Pigment Name | Color | Type |
|---|---|---|
| Zinc Oxide | White | Base Pigment |
| Titanium Dioxide | White | Base Pigment |
| Iron Oxide | Red / Brown / Yellow | Coloring Pigment |
| Lamp Black (Carbon) | Black | Coloring Pigment |
| Prussian Blue | Blue | Coloring Pigment |