hairline cracks in plaster
Don't mush anything- lol
Larger cracks are caused by the plaster moving from the lathe- I use screws to refix it to the lathe- take s special touch to not over spin and get just below surface.
No tape will mean they will come right back - unless very hairline. So use tape on anything major.
Usually by the time you've feathered them out you are resurfacing the whole wall- i do it this way often.
Screw- tape, set tape with hot mud- fan out 2nd coat hot mud-skim with premixed, sand, prime, look over & touch up mud, respot prime, finish.
"It's better to come here with questions before you screw up than to come here after and ask how to fix them."- JS