Paint Drips and Runs: How to Fix and Prevent Them
Catch a run in the first few minutes, or leave it to harden and sand it flush.
Drips and runs are what happens when there is more paint in one place than the surface can hold. They are most common on woodwork: the bottom edge of a door panel, the top of a skirting board, the edge of a cabinet door. Every decorator gets them, and the fix is simple as long as you do it at the right moment: either straight away while the paint is wet, or once it has fully hardened. Trying in between is what makes a mess.
At a glance
- Runs come from too much paint in one place: an overloaded brush or a heavy coat.
- Still wet? Brush it out straight away with a nearly dry brush.
- Started to skin? Leave it alone until it has fully hardened.
- Once hard, sanding it flush with a fine-grit block is enough, then repaint.
- Check edges, corners and panel mouldings a few minutes after each section.
Why paint drips and runs
Too much paint, in the wrong places.
A run starts when one area gets a thicker coat than the rest and gravity pulls it down before it sets. The usual culprits are dipping the brush too deep and not offloading it, brushing paint into the edges and corners of panels where it collects, applying one heavy coat instead of two thin ones, and working in cold, humid air where paint takes longer to set. Glossy surfaces that have not been keyed make it worse, because the paint has nothing to grip while it is wet.
Drips while brushing come from the same thing: a brush carrying more paint than it can hold. Dip only the first third of the bristles, tap off the excess on the inside of the tin or kettle rather than wiping it on the rim, and you will spatter and drip far less.
Fixing a run while it is wet
Brush it out lightly, then leave it.
If you spot a run within a few minutes, take a nearly dry brush and lightly brush it out, spreading the excess into the surrounding paint rather than trying to remove it. Lay off gently in the same direction as the rest of the surface and check again a few minutes later in case it re-forms.
If the surface has already started to skin, stop. Brushing paint that is tacking off tears the surface and leaves a far worse mark than the run itself.
Fixing a dried run
Let it harden fully, sand flush, then repaint.
Leave the run until it is fully hard. A thick run stays soft in the middle long after the surface feels dry, and sanding it too early just smears it. Give it at least a day or two, longer for a heavy run.
Then sand it flush with a fine-grit sanding block, keeping the block flat so you do not dip into the surrounding surface, and feather the edges until you cannot feel the run with your fingertips. Wipe away the dust, let it dry and repaint the whole panel or section, not just the sanded spot, so the finish matches.
How to stop drips and runs
Thin coats, offloaded brush, check the edges.
Two thin coats are always better than one heavy one. Offload the brush every time, work paint out from the middle of a panel towards the edges rather than into them, and finish with light strokes in one direction. After each section, look along it with light across the surface and check the bottom edges of panels and doors, where runs gather. Where you can, lay doors and cabinet doors flat to paint them.
Where our paint helps, and where it cannot
Self-levelling flows out marks; heavy coats still run.
Our paints are self-levelling, so a correctly applied coat flows out smoothly as it dries. Brushed, they are designed to keep a slight brush texture for a hand-painted look rather than a flat, sprayed finish. High opacity means two coats usually give a solid colour, so there is no need to lay it on thick. But self-levelling works on an even coat; a heavy, overloaded coat on a vertical surface can still run with any paint.
Sample it the way we would
Step 1
Paint your peel-and-sticks
Each £5.99 sample comes with three paintable peel-and-sticks. Give them two coats and let them dry fully.
Step 2
Stick them around the room
Put them on two or three walls, including the wall opposite the window, at eye level and lower down.
Step 3
Live with them for a day or two
Look in the morning, the afternoon and under your evening lamps. Move them around until you are sure.
Your questions, answered
Can you sand down paint drips?
Yes. Once fully hard, sand the drip flush with a fine-grit sanding block, wipe off the dust and repaint the whole section.
How long should I wait before sanding a run?
Until it is hard all the way through, which can be a day or two or more for a thick run. Sanding soft paint smears it.
Why does my paint keep running on doors?
Paint collects in panel mouldings and at bottom edges. Use thinner coats, brush out from the mouldings and check the edges a few minutes after each panel.
Should I add water to stop runs?
No. Thinning a finishing coat makes it more likely to run and reduces opacity. Use the paint as supplied, in thin coats.
Keep exploring
Brush Marks and Picture Framing: How to Get an Even Finish
A little brush texture is character. Ridges and frames are technique.
Roller Marks and Stripey Walls or Ceilings: Causes and Fixes
Stripes are a record of how the paint went on. Change that, and they go.
Why Is My Cabinet Paint Chipping?
Kitchen doors are working surfaces. Treat them like one.