Well-prepared and applied coatings of paint under normal circumstances should last for up to seven years. To prevent paint from deteriorating sooner than this its normal lifespan, there are prevention steps that can be taken.
Paint problems such as those listed below will allow you to diagnose causes and avoid future problems.
Most paint problems show up outdoors rather than indoors because exterior surfaces are subject to extremes in temperature and are exposed to rainfall. However, moisture seepage behind paint, a common cause of flaking, can also happen indoors. So can problems associated with incompatible primers and paint, poor surface preparation or inferior paint.
Alligatoring or checking — Paint can have many reptilian-appearing interconnected cracks. In this instance, the outer coat may not have adhered properly to the paint beneath. It could have been applied to an incompatible paint or an improperly prepared surface or the first coat may not have dried before the second coat was applied or too many layers of paint may have built up over time.
The solution is to strip the surface down to the raw wood and reapply primer and paint.
Wrinkling, running and sagging — The paint puckers, drops or lumps which is often the result of applying
too thick a coat of paint or using a poor painting technique. Another cause is painting over an undercoat that is not yet dry.
The solution is to strip the surface and repaint. Use a thinner paint and brush it thoroughly as you apply the paint. Let the paint dry completely between coats.
Flaking and peeling — The paint simply doesn’t stick to the surface. The surface may be dirty, it may have too many layers of paint already applied or the wrong type of paint may have been applied. On masonry, flaking can be caused by alkalis leaching into the paint.
The solution is to strip the surface, clean it carefully and reapply an appropriate coating.
Masonry cleaning is best left to a
Mildew — Paint appears dirty or sooty but cleans up quickly with a bleach solution. This problem is usually found in shady, protected areas that don’t get enough sun or air to prevent fungal growth.
The solution is to scrape down the area, scrub it with a three-to-one chlorine bleach solution with water or a commercial fungicide and then let the surface
dry thoroughly. Paint the surface with a mildew-resistant coating and then re-paint.
Tackiness — Paint remains sticky to the touch long after if should have dried, thus collection lint and dust. This is sometimes caused by painting over a coat of paint that has not dried or by applying alkyds in damp weather. But, more often this problem is caused by poor quality paint.
The solution is to strip the paint with a heat gun or chemical remover and re-paint the surface with a better grade of paint.
Blistering — Bubbles form under the paint. If raw wood is revealed when a blister is opened, moisture has worked its way under the paint. If a blister reveals paint, the temperature was too high when the topcoat was applied.
The solution is to check for sources of water such as leaky eavestroughs, missing caulking or winter ice dams and fix the problem before reapplying paint. If the blister showed paint beneath, then sand the affected area and repaint the surface.
Chalking — Most exterior paints are formulated so that the surface gradually breaks down into a powdery chalk that takes grit and grime away with it when rain washes it away. This feature keeps the painted surface looking clean, but surfaces that are chalking cannot hold new paint.
The solution is to scrub a chalking surface with detergent and rinse it off before repainting.
Cracking and scaling — Fissures open up in the painted surface, allowing moisture to enter which lifts off the paint. This is usually caused when
paint ages and has lost its elasticity that had allowed it to cope with temperature and humidity changes. It can also result from moisture seepage or air
The solution is to fix the moisture problem, strip the surface and then
repaint. Wash newly painted surfaces periodically.
Points to remember — Good surface preparation is the key to coating performance. Proper application techniques under the correct conditions are essential to preventing coating failures.
Each paint product is a unique blend of raw materials with specific characteristics. Understanding these characteristics is important when selecting the right paint for the right application.