How do I feather filler so the repair does not show?
A repair shows because of its edge and its porosity, not its colour. Feathering removes the edge; sealing removes the porosity. Both are needed.
- Difficulty
- intermediate
- Time
- 40 min
- Read
- 3 min
Short answer
Apply the filler wider than the damage and thinner as it goes out, so it fades to nothing rather than stopping at a line. Sand with the block flat and moving in circles beyond the repair. Then seal the patch, because bare filler drinks paint and shows as a dull spot even when it is perfectly flat.
Almost everyone fills the hole and stops there. The repair is then flat, correctly filled — and clearly visible once the wall is painted, because there is a step at the edge and a change of absorbency across it. Feathering is the technique that deals with the first, and sealing deals with the second. A repair that is invisible has had both done.
Step by step
- Spread the filler wider than the damage, not just into it.The repair should be a shallow disc considerably larger than the hole, thick at the centre and thinning out to nothing at the edges. That is what makes the transition gradual enough to be invisible.
- Use a wide blade, not a narrow one.A narrow filling knife bridges a short distance and creates ridges. A wider blade spans past the repair on both sides and rides on the sound wall, which is what produces the taper automatically.
- Take the excess off in one clean pass.Hold the blade at a low angle and pull it across the repair in one movement. Repeated fiddling drags the filler and leaves ridges you will have to sand off.
- Let it cure fully before sanding.Soft filler clogs abrasive immediately and tears out of the repair rather than cutting flat.
- Sand with a block, and work well beyond the repair.A block keeps the abrasive flat; fingers dish it. Move in circles or figures of eight and extend the movement onto the surrounding wall so the edge blends rather than being cut.
- Check by touch and by raking light, not by eye from straight on.Run the flat of your hand over it with your eyes shut — hands find ridges the eye misses. Then shine a torch along the wall at a shallow angle, which shows every remaining edge.
- Seal the repair before painting.This is the step that catches people who feathered perfectly. Bare filler is far more porous than painted plaster, so the topcoat sinks in and dries to a different sheen. Spot-prime it, or apply a mist coat over the repair.
- Paint out to a natural break if it still shows.Corner to corner rather than dabbing at the patch. On a large wall with several repairs, one full coat over the lot is often less work than perfecting each one.
Tips
- Two thin applications of filler feather far better than one thick one, and the second fills the pinholes left by the first.
- A damp sponge used lightly on a still-soft filler can do much of the feathering with no dust at all.
Common mistakes
- Filling only the hole itself. — The repair then has a hard edge all the way round, and that edge catches light no matter how flat the middle is.
- Sanding with fingertips behind the paper. — Fingers apply pressure in points and hollow the repair out. A block spreads it.
- Painting straight over bare filler. — The patch shows as a dull spot through the finish, and another topcoat rarely fixes it.
Questions people ask
Why can I still see the repair after two coats?
Almost certainly porosity rather than shape. Seal the patch and the difference in sheen disappears. If it is a visible ridge instead, it needs more sanding, not more paint.
Does this work on textured walls?
The flat repair will show against texture however well feathered. You have to reproduce the texture over the repair, or accept it, or take the texture off the whole wall.