Katie Barnes

Nail expert: the importance of parallel sidewalls for a beautiful nail finish

By Katie Barnes | 21 July 2025 | Expert Advice, Feature, Technique

Award-winning nail technician & Katie Barnes Tool Range & Education founder, Katie Clark, offers insight…

Parallel sidewalls start at the cuticle zone and end at the free edge. They mirror each other and help to give a nail enhancement a slim and slender appearance.

The term, ‘parallel sidewalls’, is frequently heard on the competition circuit, but it is not just for competition nails, as it is an essential part of all nail structures.

Have you ever looked at a nail enhancement you’ve created and thought that it looked bulky, but couldn’t work out why and where the issue lay? Maybe you tried to fix it, but made it worse or didn’t improve it at all? More often than not, the issue lies in the parallel sidewalls, and it is easy to fix.

This can be one of the most overlooked areas of a nail enhancement when both building and finish filing, but it can affect the entire finish. This is because the eye is instantly drawn to the widest area of something.

The aim is to draw the eye to the slim free edge, and smooth, straight sidewalls are leading lines which help attract the eye to this.

The point highlights the nail apex, and the two panels on either side are the parallel sidewalls. No bulk of product from the apex should be here.

Many techs forget that the apex is a point: not a band across the back third of the nail. If product is built up at the parallel sidewalls, it gives an enhancement additional weight and bulk and the nail a wide appearance.

The sidewalls should always be straight, whatever the nail shape, and there must be no fanning or bulking. Sidewalls are often referred to as the hips or shoulders of an enhancement.

The right nail has a slight roundness and bulging, indicated by the line. The key is not to file down the natural sidewalls and remove strength, but along the side panel as indicated by the circle on the left nail.

Whatever you do on one side of the nail enhancement, you must repeat on the other to achieve uniformity. How you file on one side must be mirrored on the other. Following a consistent filing routine is essential for this. The way in which you hold your file is also key. It must be held flat against the sides of the nail and roll over the enhancement.

Follow my filing routine video by clicking here.

It is necessary to check a nail enhancement from the client’s view, in order to notice whether there is any bulk at the parallel sidewalls. This will help you to make the nail structure slim and slender, and take your work to the next level.