How to get straight lines with masking tape

To get straight lines with masking tape, stick the tape onto a clean, dry surface, press the edge down firmly, seal it with a thin coat of the wall colour and remove the tape when the paint is touch-dry but not yet hard. That way the paint does not bleed under the tape and the line stays sharp.

Choose the right tape

Not every tape will do. Paper masking tape is made to come off without leaving adhesive behind or pulling off paint. Ordinary packing tape or sticky tape is no good for this.

For freshly painted walls or delicate surfaces, choose low-tack tape.
For normal surfaces, ordinary masking tape will do.
For very demanding lines, there are tapes made for fine edges. Read the packaging.

Check the maximum time the tape can be left in place. If you leave it for weeks, it can be hard to remove and may leave residue.

Prepare the surface

Tape only sticks well to surfaces that are clean, dry and dust-free. Wipe the areas where you will stick it with a dry or slightly damp cloth. Wait for it to dry. On walls with dust or grease, the tape does not grip and paint gets underneath.

If the previous paint is still fresh, wait for the time stated on the tin. Tape on soft paint can pull it off.

How to stick the tape on

Cut pieces that are not too long, so you can control them.
Stick the tape right on the line where you want the edge. Take care to stretch it without distorting it.
Use a spirit level or a ruler if you need a very straight line.
Run a fingernail, a plastic scraper or a plastic card along the edge to press it down firmly.
At corners, cut the tape and butt the ends together instead of folding it, so no gaps are left.

The edge of the tape is the most important point. If it lifts, paint gets in.

The trick to stop paint bleeding

Even with the tape well stuck down, there may be tiny gaps. The simple solution is to seal the edge. First brush a very thin coat of the colour already on the wall, or clear paint, over the edge of the tape. If any gets underneath, it is the same colour as the wall and does not show. Let it dry and only then paint with the new colour.

If you are painting two different colours side by side, use this trick with the colour already on the wall.

Painting next to the tape

Use little paint on the brush or roller next to the tape. Too much paint runs under the tape.
Brush away from the tape, or along it, without pushing the paint against the edge.
Apply the coats you need with the tape in place, without removing it between coats, if the paint allows.
Avoid painting heavily over the tape, so you do not create a thick film.

When and how to remove the tape

The timing matters. If you remove the tape while the paint is still very wet, it can run. If you wait until it has dried completely, the paint forms a film and can tear at the edge.

The ideal moment is when the paint is touch-dry but not yet completely hard. Pull slowly, at a low angle, drawing the tape away from the painted line. If you see the paint tearing, score along the edge with a utility knife before pulling.

Tip: If paint still gets underneath, do not rub it straight away. Let it dry and touch up with a fine brush and the right colour. If the paint is still fresh, a damp cotton bud will clean up small flaws.