Plaster peeling off during troweling is like a cake falling-annoying, and usually a sign something went wrong earlier. The most common culprit is poor surface preparation: if the wall wasn't cleaned, sanded, or primed, the plaster can't grip properly. Dust, grease, or old paint creates a barrier, so when you trowel, the wet plaster slides right off instead of bonding.
Another reason is applying the plaster too thickly. A heavy coat can't dry evenly- the top layer sets while the bottom stays wet, creating a weak spot that peels when you press with the trowel. It's like spreading butter too thick on toast-it slides off instead of melting in.
Timing is also a factor. If you trowel too early, when the plaster is still runny, the pressure of the trowel pushes it off the wall. If you wait too long, the top layer dries, and troweling breaks the bond between layers, causing peeling.
Finally, the plaster mix itself might be off: too much water makes it soupy and weak, while too little makes it dry too fast, creating a crust that peels. Fixing it means prepping the wall properly, applying thin coats, and troweling at the right time. Do that, and your plaster will stick like glue-no more frustrating peeling.
