Paint Problems – Surface Defects and Paint Coating System Problems
Read on to understand what paint problems can occur when you are painting and learn how to diagnose and fix the problem.
Paint Problems – Surface Defects
Efflorescence is a white fluffy surface deposit that is caused by salts in the plaster being drawn to the surface. The moisture evaporates and the efflorescence appears. Dry brushing will remove it.
To remedy this paint problem – do not wash with water, as this will aggravate the problem. For the first coat, if it is a new surface use latex, if an old surface use latex or alkali-resisting paint.
Mould or Fungus
Mould or Fungus is multi colored or patches on infected areas. The cause is airborne spores feeding and multiplying on the organic matter in the paint together with poor ventilation, dampness and condensation. The best form of prevention for this paint problem is to find the cause of the dampness and correct it. Sterilize with a fungicidal solution then check for the problem reoccurring. Then paint with fungicidal paint.
Paint Problems – Coating System Defects
Blistering is bubbles or blisters in the paint film. It is caused by water vapor being attracted by heat and forming spaces beneath the film, or resins from knots in the timber being attracted to heat, or paint being used on surfaces which have extreme heat. To prevent this paint problem, make sure that the substrate is completely dry before painting. Remove any knots and replace with plugs. Use heat resistant paints for areas that have extreme heat. Select light paint colors as they reflect more heat.
Chalking is a powdery deposit being formed on a dry paint film surface. The powder is unbound pigment. This is caused by painting over surfaces that haven’t been sealed sufficiently, or the paint is deficient in binder, caused by over thinning. When using interior paints on exterior surfaces it can also occur. To prevent this always seal surfaces correctly and only thin paint to the specifications.
Checking, Cracking, Crocodiling, Alligatoring
Checking, Cracking, Crocodiling, Alligatoring are all names for splits that appear in the film of the surface coating. It is caused by the use of excessive dryers or recoating before the under coat is dry. To prevent this paint problem add only a minimum amount of dryers and allow the specified time to dry between coats – don’t rush!
Cissing is globules or misses in the paint film where it has not adhered to the substrate. Painting greasy or very smooth shiny surfaces causes it, or finishing over an oily undercoat. Thoroughly washing and rinsing the substrate can prevent it as well as a light sand to remove the shine.
Flaking is paint or varnish lifting away from the surface in flakes because of a breakdown of the adhesion. It occurs when painting damp surfaces, especially timber, or painting powdery surfaces. To prevent this ensure that all the surfaces are completely dry and that the correct sealer and preparation has occurred.
Flashing is patches of uneven sheen with semi gloss finishes. It is caused by not keeping a wet edge while applying the paint. To prevent this keep a wet edge and ensure that the air temperature and movement meet the specifications and the correct equipment, brushes etc are being used and the coating system is as required.
Rain Spotting, Cratering
Rain Spotting, Cratering is craters or holes on the surface of a dry paint film. It is caused by rain falling on a wet film, condensation or dew on a wet film. To prevent this always check the weather conditions before commencing to paint. Avoid painting in high humidity.
Rivelling is wrinkles occurring in the paint film as it dries. It happens because the paint has been applied too thickly. To prevent it, ensure that the paint is applied to the normal film thickness.
Saponification is a sticky paint film that is oozing with a brown soapy liquid. Applying an oil paint on new alkali surfaces or applying paint to surfaces that are likely to be splashed by alkali solutions causes it. To prevent this seal the substrate with an alkali resistant paint or latex paint or chemically resistant paint.
Sinkage is the failure of a paint or varnish to keep up its original shine or sheen. Applying the paint over insufficiently sealed absorbent surfaces, or using the wrong paint system causes it. A wet paint film may be affected by damp weather or condensation. To prevent this ensure surfaces are properly sealed, use the correct paint system, and apply paint in the conditions specified on the can.
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