>>11456679
example of what the decal softener allows you to do
this is the VF-19EF/A 1/72 kit from hasegawa, anything colored you see on it are decals, very large ones or that go in curved surfaces, such as the ones circled in red

if you just use water to put them on the kit, they end up with air bubbles and looking like a wrinkled carpet, the softener basically allows you to iron them, so they stick and properly adhere to the form of the surface the decal is on