When we first started using plastic trowels over a year ago we done a large ceiling over artex that was all over the place. First coat we done a 50/50 multi bonding but never mixed enough so had to mix up more after laying it on. As you know with multi/bonding it flash sets so we had most of the ceiling screaming for a second coat and the last bit soaking. Anyway got the second coat on and it flattened terrible, few wets and dry and it still looked bad. Two passes with plastic and it looked amazing and we thought we had saved it. Got a call back few weeks later as after the painter had been in and new lights had been fitted it looked terrible, first call back we'd had in years. Reskimmed and painted it our selfs but now very wary of how good a shiny ceiling really is.