A primer is a preparatory coat put on wood or other materials before painting. If you were to look at the surface of wood under a microscope you would be shocked at how rough it really is, even after you have sanded it.
Depending on the species of wood the porosity can vary widely. Priming is formulated to do several mission-critical things to all types of wood. There are many benefits to priming wood:
1. It seals the original wood so that paint doesn’t soak into it.
2. It prevents bleed-through from knots, other natural blemishes and colouring in bare wood.
3. It helps to hide joints or seams.
4. It ensures better adhesion, primers physically and chemically bond the paint to the surface.
5. It increases wood durability.
6. It provides additional protection to the wood.
7. Primer has high-solids content that helps fill in the wood grain, creating a smooth surface for the finish coat. It evens out the surface.
8. It enhances and improves the life of the paint.
9. It improves the appearance of the paint.
10. Modern primers are water based and dry very rapidly.
11. It optimises the surface so fewer top coats of paint are required.
12. Primers speed up the job.
13. Often works out cheaper.
14. It prevents peeling, cracks and fading of the paint.
15. Primers sand very easily (priming sometimes requires a light sand before painting).
16. It covers imperfections like repairs in the wood.
17. It helps block out stains and odours.
18. It brings the colour back to neutral, so the new paint goes on in its true colour.
Certain primers are often formulated to work with specific finish paints. It is clear that it is always better to prime wood before painting.