How to Fix Lifting, Granulation, Cracking and Delamination In Wood Finish？
In professional wood finishing for high-end furniture and wooden musical instruments, some serious coating defects do not appear immediately after spraying. Problems such as lifting, grainy particles, cracking, delamination, and loss of gloss usually emerge after drying or storage, leading to batch rework and customer complaints.
These failures are mainly caused by mismatched coating systems, improper mixing, poor base treatment, and unstable construction environments. Below are practical causes and effective solutions for factory mass production.
Lifting
-The topcoat dissolves and lifts the primer layer, causing wrinkling, peeling and blistering on the wood surface..
Cause：
- Hardener dosage is insufficient, results in inadequate paint hardness or incomplete drying between coating layers.
- An inappropriate combination of paints of different properties, an overly strong solvent in the upper layer of thinner, or the application of PU/AC system paint on the NC coating can cause the underlying coating to lift up.
- The undercoat is not fully cured before re-spraying.
- The paint viscosity is too high.
Preventive Measures：
► Use matched primer and topcoat from the same coating series.
► Ensure full interlayer drying before applying the next coat.
► Follow standard paint and hardener mixing ratio strictly, and stir thoroughly before use.
► Adjust paint viscosity.
Granulation
-The finished surface feels rough with tiny visible particles, losing smooth and transparent texture.
Cause：
- Dust and floating impurities in the spray booth.
- Insufficient paint stirring and undissolved powder particles.
- Over-fast evaporating thinner and improper viscosity.
- Dirty spray gun and unfiltered paint liquid.
Preventive Measures：
► Keep a dust-free spraying environment.
► Stir paint evenly before use and filter the liquid.
► Adjust viscosity and use climate-adapted thinner.
► Clean spraying tools regularly to avoid impurity residue.
Cracking
-Fine or large cracks appear on the paint film after days or weeks of curing.
Cause：
- Excessive hardener addition makes the film too brittle.
- Too thick single coating layer.
- High wood moisture content causing wood shrinkage.
- Mixing different brands or different types of paint
Preventive Measures：
► Test wood moisture and keep it below 12% before painting.
► When applying paint, the amount should be appropriate and even in one coat. When mixing paint, pay attention to the proportions and factors such as season and climate.
► Ensure the Hardener is mixed according to the specified ratio.
► Test the paint's solids content or replace the paint.
►When applying multiple coats, pay attention to the drying state between layers.
Delamination
-The paint film separates from the wood substrate or peels off between coating layers.
Cause：
- Wood surface contaminated with oil, wax and dust.
- Poor sanding quality between layers.
- Long interval time after intermediate sanding.
- The paint has an excessively high solids content or too much hardener has been added.
- Different types of paint were used in the upper and lower layers.
Preventive Measures：
► Completely clean and degrease the wood surface before spraying.
► Standardize interlayer sanding to ensure good adhesion.
► Finish topcoat spraying shortly after sanding.
► Use high-adhesion PU sealing primer to strengthen base bonding.
Summary Wood Coating Problems：
These four advanced defects are the main reasons for after-sales problems and order returns.
Using our complete coating system can effectively solve lifting, particle roughness, cracking, delamination and gloss fading. It provides stable, durable and high-transparency finishing for furniture and musical instrument factories.
This guide addresses common wood coating problems. It helps avoid costs associated with unnecessary material waste or production line adjustments while promoting efficient material usage and preventing potential issues. If the suggested solutions do not resolve your coating quality or process issues, please contact your coating supplier.
If you require a stable wood coating solution and technical guidance for your production line, please contact us to request free samples and wholesale quotes!
