Paint Defects 3 – Wrinkling

1 July 2016
Posted by: Stm Coatech
Category: Educational Articles

Textured paint surface with uneven wave type formation that occurs when the paint surface dries faster than the substrate coats. This problem only occurs in the presence of synthetic enamels. Paint wrinkling can occur if paint is applied too thickly or under adverse environmental conditions. It is more likely to happen when using alkyd paints. Fortunately, a paint wrinkling problem is easy to remedy.

It produces a series of folds and undulations in the surface layer of paint lifting and giving a wrinkled appearance.
The origin of this defect is determined mainly by the action of solvents or reducers of the previous layers, which either by reacting with the substrate or because they are trapped and try to come out to the surface, lift and swell the last layer of paint.
This defect is usually located in the finish layers of paint an can be observed during application or after drying of the paint.
Paint film forms creases, folds, and slight ridges. Film surface appears thick and leathery.

CAUSES:
- The solvent/reducer used in applying the last coat of paint reacts with the previous layer of paint and causing wrinkles.
- Use of cleaning solvent incompatible, inappropriate and aggressive during the preparation/cleaning of surfaces.
- The paint has not dried enough, so that the solvent swell without break the last layer of paint producing wrinkles.
- Do not let the flash time between coats of paint to get the evaporation of solvents.
Example – When refinish a bilayer system (basecoat +clearcoat) before proceeding to paint clearcoat is used the same paint thinner or reducer to clean the surface, it reacts with the basecoat due this paint when dry is very sensitive, causing wrinkles.
- Paint applied too thickly (more likely when using alkyd or oil-based paints).
- Painting during extremely hot weather or cool damp weather, which causes the paint film to dry faster on top than on the bottom.
- Exposing uncured paint to high humidity levels.
- Painting over contaminated surface (e.g., dirt or wax).
- Painting over a glossy surface that has not been sanded.
- Applying a top coat before the primer or first coat has dried thoroughly.
- Applying a hard finish over a softer coat without priming, or painting over a glossy surface without sanding.
PREVENTION:
- Select the correct paint system, so that all products are compatible with both the substrate and between the various layers of paint.
- Make sure the paint has dried correctly, thoroughly either by ratio of catalyst or curing time.
- Respect the minimum flash times between coats.
- Keep to recommended number of coats and film build.
- Ensure drier solution is added as part of the mixing formulation.
- Ensure correct drying conditions . Avoid painting in high humidity or extreme temperatures(below 50º F and above 100º F)
SOLUTIONS:
- For minor faults, dry the surface thoroughly,
- Sand back to a hardened layer and then refinish.
- Wipe the affected area with a damp cloth, making sure the surface is clean,
- If needed, prime bare areas with the appropriate primer, allowing it to dry completely,
- Reapply the paint, following the manufacturer’s instructions,
- For severe wrinkling faults, strip the entire paint layers with paint stripper or by mechanical bead blasting and refinish to specification.
REFERENCES:
1. Painting for Painters, Wrinkling, date of access: 30 June 2016 http://www.paintingforpainters.com/wrinkling-paint.html
2. Guthrie Bowron, Common Paint Problems, date of access: 30 June 2016 http://www.guthriebowron.co.nz/assets/Common-Paint-Problems.pdf
3. Benjamin Moore, How to Fix and Prevent Paint Wrinkling, date of access: 30 June 2016 http://www.benjaminmoore.com/en-ca/for-contractors/how-to-fix-and-prevent-paint-wrinkling
4. Dunn Edwards Paint, Paint Problems Solver, date of access: 30 June 2016 https://www.dunnedwards.com/howto/paint-problem-solver/wrinkling