Whenever cutting or trimming paper or film, it is always best to use a cutting mat. The slightly soft but firm surface protects the tip of the blade and makes it last longer.
The smooth, clean, surface is nice to work on and is ideal when trimming prints. Small cuts almost disappear and the mats are normally double sided so will last a long time.
Deeper cuts will NOT heal up. The mats are designed for light trimming and cutting only. For heavy cutting, such as MDF boards with a utility type knife. use a piece of old carpet.
These mats are 3mm thick. Cutting mat colours may vary. Most have a grid pattern printed on one side but don’t rely on the accuracy of the scales.