There are couple of reasons for the peeling of varnish on wooden floors and if this has happened, then the only way to fix it is a complete sanding and re-polishing of the timber floor, preferably by a professional.
1. If you use a surface finish such as solvent based polyurethane, waterbased polyurethane or oil modified polyurethane, the light sanding between the coat needs to be done properly using a new 220 grit sanding screen with buffing machine. If not, the top coating will not adhere properly and start peeling off a couple of months after the job's completion.
2. There are oily timbers such as Brushbox, Spotted Gum, Cypress or Tallowwood, which need to be primed before applying the top coat, otherwise, the top coating will start peeling off over time.
3. Timber movement will delaminate the top coating near the gaps between the boards.
4. If you had used a water base, but an oil based stain was not totally dry under it, this can cause the finish to peel, due to the solvents in the stain trying to escape through the water based film.
5. If a floor was finished with penetrating oil or wax, the floor should be sanded back to bare the timber properly. Otherwise the substance will still remain on and in the grain of the boards. Neither water base urethane or oil based finishes will bond to such a surface.
Peel off the vanish of polyurethane recoating
Poor applicator technique leaves streaks on wooden floors.
The roller marks are not only related to the application technique but also related to the coating material (whether it is water based, solvent based or wax), the sheen (satin or matt), and the temperature when the coating was executed. Therefore, only highly experienced professionals could avoid this hassle.
If the roller marks already exist, most of the time, the only way to fix the problem is to re-sand it back to the bare timber and polish again.
Roller marks of the waterbase finish
White Line Syndrome
White lining is associated with the movement of board edges as they shrink, causing the coating to stretch across the gap.
It tends to occur with water based finishes and in severe cases, the finish may split and delaminate.
Flooring can shrink if it is not correctly acclimatised before installation. It can also shrink if there is a change in air humidity levels after installation, such as having a heating or cooling system turned on.
White line syndron of waterbase finish on dark stained floors