[DIY] Groundwork treatment for super tough bond marks

This time, we will be preparing the groundwork before putting putty on a wall that has quite a lot of bond marks.
This is the first time I've experienced this kind of strength with this amount.
I will do my best to prepare the groundwork while trying out various tools to get a nice finish.
If you take some time before applying DIY wallpaper, you will notice a different result.
I would be happy if it was helpful