Patchy paint after a second coat is one of the most common painting frustrations for NZ homeowners — but the good news is it's almost always fixable. The key is understanding why it happened before you reach for the roller again, so you don't end up in the same situation a third time.
Why Does Paint Go Patchy?
Before you fix the problem, it helps to know the cause. Common culprits include:
- Insufficient film build — rolling or brushing too thinly, leaving some areas with less paint than others
- Skipping or skimping on primer — bare or repaired surfaces absorb paint unevenly without a proper primer coat
- Poor surface prep — grease, dust, or glossy surfaces prevent paint from bonding evenly
- Cheap or wrong roller nap — a roller with the wrong pile thickness for your surface texture leaves an uneven finish
- Paint applied in direct sun or high heat — common in NZ summers, this causes the paint to dry too fast before it can level out
- Colour change without enough coats — going from a dark to a light colour (or vice versa) often needs three or more coats
- Inconsistent dilution — over-thinning paint reduces its hiding power
Assessing the Patchiness
Stand back and look at the wall in raking light (light coming from the side, such as from a window). This will reveal whether the issue is:
- Sheen variation — some patches look flat, others look shiny. Usually caused by uneven application or absorbency differences.
- Colour variation — some areas look lighter or darker. Often a coverage issue.
- Texture variation — roller marks, brush strokes, or lap marks. Usually a technique or drying-time issue.
Identifying the type of patchiness will guide your fix.
What You'll Need
| Item | Purpose |
|---|---|
| Fine sandpaper (180–220 grit) | Lightly key the surface |
| Tack cloth or damp rag | Remove dust before repainting |
| Quality roller (appropriate nap) | Even application |
| Angled brush | Cutting in at edges |
| Matching paint (same batch if possible) | Colour consistency |
| Primer/sealer (if needed) | Seal absorbent patches |
Step-by-Step Fix
1. Let the Paint Cure Fully
Make sure the existing coats are fully dry — not just touch-dry. Most water-based paints need at least 2–4 hours between coats, but in cooler or humid NZ conditions (think Wellington winters or a damp Southland morning), allow longer. Check the manufacturer's data sheet for recoat times.
2. Lightly Sand the Patchy Areas
Using 180–220 grit sandpaper, lightly sand any raised edges, roller marks, or lap lines. Don't sand aggressively — you just want to knock back any high spots and give the surface a light key. Wipe down with a tack cloth or barely damp rag and let it dry completely.
3. Spot-Prime if Needed
If certain patches are noticeably more absorbent (they'll look duller and soak up paint faster), apply a spot coat of primer or sealer to those areas first. This is especially important on repaired plasterboard, filler, or bare timber. GIB recommends sealing all stopped and sanded plasterboard repairs before topcoating. Allow the primer to dry fully before proceeding.
4. Apply Another Full Coat — Properly This Time
Don't just touch up the patchy spots — this almost always makes things worse by creating new edges and sheen differences. Instead, repaint the entire wall or ceiling in one continuous session:
- Use a quality roller with the correct nap for your surface (typically 10–12 mm for smooth walls, 15–20 mm for textured surfaces)
- Maintain a wet edge — work quickly and keep overlapping into wet paint to avoid lap marks
- Apply paint in a 'W' or 'M' pattern, then back-roll to even it out
- Avoid going back over areas that have started to dry
- Paint in consistent lighting conditions and avoid direct sun or strong draughts
Resene and Dulux both publish excellent application guides on their websites that are worth reading before you start.
5. Consider a Third Coat
If you're making a significant colour change, or if the surface was in poor condition, a third coat is often necessary to achieve a uniform finish. This is normal — it doesn't mean you've done anything wrong.
Tips to Prevent Patchiness Next Time
- Always use a quality primer suited to your substrate before topcoating
- Buy enough paint from the same batch (check the batch number on the tin) to complete the job
- Paint in mild, stable conditions — ideally 10–25°C with low humidity
- Don't over-dilute your paint; follow the manufacturer's guidelines
- Invest in a good-quality roller and brush — cheap tools are a false economy
For paint selection and advice, your local Resene ColorShop, Dulux trade store, or Wattyl stockist can help you choose the right product for your surface and conditions. Supplies are also available from Bunnings and Mitre 10.
When to Call a Professional
If you've applied three coats and the patchiness persists, there may be an underlying issue — such as moisture coming through the wall, a failed previous paint system, or a substrate problem — that needs professional diagnosis. Persistent sheen variation on ceilings can sometimes indicate a ventilation or condensation issue worth investigating under the Healthy Homes standards.
A qualified painter will also achieve a more consistent finish on large or high-profile surfaces like open-plan living areas or feature walls. You can find experienced local painters on tradedirectory.co.nz.