Whether you are dealing with hardwoods, softwoods, MDF or other materials, there are some general guidelines you should follow to achieve the best finish and adhesion.
A typical sanding preparation process for timber/MDF involves starting with a 120-grit sandpaper, then progressing to 180-grit, and finally finishing with 240-grit. While this is a common approach, it's not an absolute rule. Working through these different grit level ensures that the surface is properly prepared for priming or lacquering. It creates a smooth finish and promotes good adhesion between the coating and the timber.
Mechanical sanding equipment is typically used for this process, such as a drum sander or orbital sander. While certain items can be sanded by hand, it is generally recommended to use a machine whenever possible to achieve a consistent and thorough preparation. It’s also important to ensure the surface is carefully blown and/or wiped to remove all sanding dust before painting.
In some cases, certain timber types and coating combinations can result in grain or fibre raising, which means the fibres of the substrate may stand up after the initial sanding. This is common when applying water-based primer on MDF, for example. To address this issue, a thorough denibbing process is required between coats. Using a higher grit sandpaper such as 240-320 grit, ideally with a mechanical sander, can level the surface and provide a smooth finish for the subsequent coats.
Sanding not only creates a foundation for a smooth and flat finish, but it also enhances the adhesion properties, allowing each coat of paint or coating to adhere effectively to the previous one. This overall process results in a smooth, flat finish with optimal adhesion properties.
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You will also want to consider your corner profiles – a very sharp corner can look very clean and modern, but it is hard to achieve a good paint film over this, leaving it very prone to damage. A slight sanded rounding to the corners can help significantly in the long-term durability of the coating.
Even a great coating system can’t absorb the impact of poor preparation – take the time and care to do it right, and you’re a long way towards an optimum finish!
