Paint Coalescence - Causes & Solutions
Paint coalescence, defined as paint clumping together on a surface instead of spreading evenly, is typically caused by several factors. The first and most important one of these is when paint does not properly bond with a surface that is normally ideally suited for it. Often, this is because the surface is too cold.
Cold is problematic
Both latex and oil based paints do not properly bond to a cold surface. In the case of oil based (enamel) paints, this is because condensation forms at colder temperatures, creating a thin film of water. This repels the paint and does not allow it to bond, making it coalesce. In the case of latex paints, which are water based, the paint takes much longer to dry, eventually causing the pigments to separate out, and coalesce into lumps.
Addressing the cold
Perhaps the easiest way to deal with surfaces that are too cold is to simply heat them up. Quite often, professional contractors or painters bring propane or electric heaters into the room in question, and can thus quite effectively perform the painting job and have it dry more quickly. Likewise, if paint coalescence has already occurred, often heating the freshly painted surface causes the paint to properly spread before it dries.
Addressing the moisture
Another possibility is to deal with the moisture directly, rather than the temperature. Options for this include treating the surface in question with drying agents before attempting to paint it, or by using paints specifically designed for slightly moist surfaces. These paints have built in astringent agents that remove the moisture from the surface as the paint bonds and dries.
Ignoring the cold
Some people also choose to simply use paints that are designed for efficiency at temperatures as low as the freezing point. Like the paints designed for use on slightly moist surfaces, many of these have built in astringent agents.
In painting, like in almost every other endeavor, the best advice that anyone can give is that it is far wiser to plan things out ahead of time than to try and solve problems after they occur.
Primers and Finishes
Priming is essential for better adhesion, sheen uniformity, mildew control and durability.
Select a top quality interior paint in the color and sheen of your choice.
Substrates, Primers
Substrate: Various
Primer: Usually None
Finish Coats: 550 Super Latex Interior Flat Wall Paint
1610 Sat-N-Sheen Int. Low Sheen Finish
1650 Acry-Plex Interior Latex Semi-Gloss
1685 Dura-Poxy + Int./Ext. Semi-Gloss Acrylic En.
1680 Dura-Poxy + Int./Ext. Gloss Acrylic En
