Using the Background layer

The Background layer is at the bottom of the Layer Editor. It cannot be drawn on. 

You can do one of two things with the Background layer, change the color of the background (canvas) or create a transparent background or alpha channel.

Why create an alpha channel


It’s handy when compositing (combining) an assortment of images. The alpha channel will enable the background of one image to show through the alpha channel of the other images. This is because the alpha channel doesn’t contain any pixels. 

Sketchbook will display a grey and white checked pattern to indicate an alpha channel. For how to create an alpha channel, see Creating an alpha channel‍.



The iOS Photos app is known to convert PNG files to JPG, with the most obvious result being the loss of a transparent background. It is more common for files over 4k and under 360px, but it can happen to any file. The only workaround if this is happening on your device is to save your PNGs to Files instead of to Photos.