When it comes to painting surfaces it is very important to prime them. The purpose of a primer, especially a wood primer is to allow the primer to penetrate the surface allowing products applied to the top it to stick to the surface.

When it comes to the surface itself the preparation is the key, rubbing the surface down and protecting the knots with two coats of fresh knotting before applying the primer is the best solution for this job.

Here we have a piece of timber which has already been primed. It has a nice even coating and it's ready for a good quality undercoat over the top.

For metal we have a special primer containing zinc phosphate. This is designed to go on to metal and reduce the amount of corrosion, so you will get less rusting over a period of time.