Interior paint problem solver

Even the most professional painters can run into problems. But the good news is that there are solutions for almost all of them. For each problem you’ll find a guide to identifying it, its causes, solutions and in some cases, how to prevent the problem from happening altogether.

 Interior – Blocking

Blocking is the undesirable sticking together of two painted surfaces when pressed together (e.g., a door sticking to the jamb).

It happens when a sufficient drying time has not been allowed before closing doors or windows and is more common when using low-quality semi-gloss or gloss paints.

How to fix it:

Use a premium semi-gloss or gloss acrylic enamel paint like Diamond Ace Matt Enamel. Low quality semi gloss and gloss water-based paints can have poor block resistance, especially in warm, damp conditions. Always follow paint label instructions and dry times. Acrylic enamel paints have a better early block resistance than vinyl latex paints, or solvent-based enamel paints. Finally, a light sprinkle of talcum powder over tacky areas of paint relieve persistent blocking.

 Interior – Burnishing

The gloss of a paint can wear down when subjected to rubbing, scrubbing or having an object brush up against it.

Cracking and flaking is caused by:

  • Use of a lower quality paint that has inadequate adhesion and flexibility.
  • Over thinning the paint or spreading it too thin.
  • Poor surface preparation especially not applying a primer before painting.
  • Poor adhesion of the underlying coats.
  • Excessive hardening and embrittlement of alkyd paint as the paint job ages.

How to fix it:

If caught early, it may be possible to correct superficial cracking by simply removing the loose or flaking paint with a scraper or wire brush, sanding to feather the edges, then priming any bare spots and repainting.
However, if the cracking goes down to the substrate, you’ll have to remove all of the paint by scraping, sanding and/or using a heat gun. You can then prime and repaint the surface with quality products like Diamond Ace Extra Smooth Primer Filler.

 Interior – Cracking, Flaking or Peeling

Cracking, flaking or peeling is the splitting of a dry paint film. This is a problem that needs fixing as it can lead to complete failure of the paint. Initially, the problem appears as a hairline crack, before evolving to flaking of paint chips.


Burnishing commonly occurs where a flat paint is used in highly trafficked areas rather than a paint with a higher level of sheen. Frequent washing and spot cleaning can also exacerbate burnishing, especially on lower quality paints with poor stain resistance and poor scrub resistance.

How to fix it:

Paint heavy wear areas such as doors, window sills and trim with a premium semi gloss or gloss acrylic enamel like Diamond Ace Synthetic Enamel. This type of paint offers both durability and easier cleaning capability. In high traffic areas, choose a low sheen, semi-gloss or gloss rather than a flat sheen level. Clean painted surfaces with a soft damp cloth or sponge and non-abrasive cleansers; rinse with clean water.

 Interior – Foaming or Cratering

Foaming or cratering is the formation of bubbles (foaming) and resulting small, round concave depressions (cratering) in a paint film, during paint application and drying.


Several things can cause foaming or cratering:

  • Shaking a partially filled can of paint.
  • Use of low quality paint or very old latex paint.
  • Applying (especially rolling) paint too rapidly.
  • Use of a roller cover with wrong nap length.
  • Excessive rolling or brushing of the paint.
  • Applying a gloss or semi-gloss paint with a long nap roller.

How to fix it:

All paints will foam to some degree during application; however, higher quality paints are formulated so the bubbles break while the paint is still wet, allowing for good flow and appearance. Avoid excessive rolling or brushing of the paint or using paint that is more than a year old. Always apply gloss and semi-gloss paints with a short nap roller.

 Interior – Lapping

Have you noticed that there are areas of denser color or higher gloss where wet and dry layers overlap during painting?

This is caused by not maintaining a ‘wet edge’ while painting.

How to fix it:

To maintain a wet edge, apply your paint towards the unpainted area and then back into the just-painted surface. Brushing from “wet to dry,” rather than the other way around will help produce a smooth, uniform appearance. It’s also wise to minimise the area being painted and plan for interruptions at a natural break, such as a window, door or corner. Using a top quality water-based paint makes it easier to avoid lapping problems because higher solids (pigments and binder) content makes lapped areas less noticeable. If substrate is very porous, it may need a primer/sealer to prevent paint from drying too quickly, reducing wet edge time and therefore making lapped areas noticeable. Solvent-based paints generally have superior wet edge properties, and therefore less lapping.

 Interior – Mould

If you’ve noticed black, grey or brown areas on your painted surface, chances are you’re dealing with a mould problem.

As with mould anywhere, interior mould is caused by moisture. It’s often found on areas that are damp, and receive little natural light and are poorly ventilated (bathrooms, kitchens and laundries). Mould is more likely to occur after use of a lower quality paint, failure to prime bare wood before painting, or if you’ve painted over a coating of mould without removing it.

How to fix it:

First, test for mould by applying a few drops of household bleach to the discolored area.If it disappears, it is probably mildew. Remove it by scrubbing with a diluted household bleach solution (one part bleach, three parts water). Be sure to wear rubber gloves and eye protection. Power washing is also an option. Then, rinse thoroughly, prime any bare timber and apply one or two coats of a top quality paint like Diamond Ace Matt Finish. If possible, install an exhaust fan to help prevent re-growth.

 Interior – Mud Cracking

Deep, irregular cracks resembling dried mud in your paintwork is called mud cracking.

Mud cracking can occur when:

  • Paint is applied too thickly, usually over a porous surface.
  • Paint is applied too thickly, to improve inherent poor hiding (coverage) of a lower quality paint.
  • Paint is allowed to build up in corners upon application.

How to fix it:

Remove the cracked paintwork by scraping and sanding. Prime and repaint the surface with a premium water-based paint like Diamond Ace Water Based Acrylic Primer and a roller with appropriate nap length. Sanding the surface smooth before repainting with a premium water-based paint can also repair mud-cracked areas. Premium quality paints have a higher solids content, which reduces the tendency to mud crack. They also have very good application and hiding properties, which minimises the tendency to apply the paint too thickly.