10-14-2012 07:32 PM
We finished painting the exterior of our house with Behr paint. The house is 10 years old and this is the first paint job since it was new. We have composite lap siding. The process we used was to lightly sand, then wash with just water. Let the house dry for a week. Primed the house, and let it dry for a few days. Applied the first coat with roller and brush and let it dry for a few days. Applied the top coat with a roller and brush.
Now basically every wall of the house has blotches. And I don't mean just a few, it is the entire house down the length of every board and it is getting worse by the day. The paint looked great when it was applied, and now every wall of the house looks like crap.
I was hoping this was just part of the drying process, but I am guessing that is just wishful thinking. Anyone else have this problem, and if so what did you end up doing? I am thinking my only option is to repaint the house with a different brand of paint.
10-15-2012 11:31 AM - edited 10-15-2012 11:32 AM
Hello C-E. Sorry for the bad experience...let me see if I can shed some light on the situation.
The cause of the "blotchy" painted surface can be from several different possibilities - none of which were directly caused by all your hard work.
Paint Sheen: All paints react to inconsistencies in application. For example; when satin finish paint is applied with a brush and roller, there will be areas where one stops and then is continued. Those overlapping areas have a slightly larger concentration of paint and as a result will dry slower and/or be somewhat shinier. When this is viewed on a large wall – it gives the appearance of splotchy inconsistent sheen. Just giving the paint some time to “cure” (or harden through) will solve this. It may take several weeks depending on weather conditions.
Surfactants (in Emulsion Polymerization): A fancy word that simply describes the slow curing process of chemicals in paint (Emulsion). Surfactants are detergents that are designed to slowly work their way to the surface of the paint film – carrying moisture and other chemicals with them to aid in evaporation. When certain conditions occur like sudden bouts of high humidity or extreme rapid temperature change…the process excels. So in essence, those chemicals are drawn to the surface and just sit there. This will add to the inconsistent surface appearance and blotches will appear. This is most commonly found with darker colors and will eventually go away, but could take several months. You can get rid of them in a much faster way by simply rinsing down the siding with a garden hose. Test an area to see what pans out.
Mildew: You said in your question that you rinsed the existing surface with water before priming and painting. Water alone is not the best way to prepare a house for painting…A cleaning solution that kills surface mildew and loosens dirt/grime is what is recommended. It is possible that some mildew or contaminant has influenced the paint performance, but is unlikely. It would take months for the reaction to take effect.
Please let me know how it works out. You certainly have worked hard on this project and I would hate for you to put much more work into it than is necessary.
10-15-2012 02:25 PM
I would concur with Paint Pro's comments. There are many factors which can affect paint sheen, some result due to painting technique, and some due to the nature of acrylic paints.
Keeping a "wet edge" is extremely important in avoiding lap marks. Continuing along the entire length of lap siding until some natural cut-off point is reached is important. Unfortunately, this is often difficult for homeowners who don't possess the scaffolding that the pro does. Water borne paints set up extremely fast.
Working out of the sun and in cool temperatures is also important in getting the paint to set slowly. More than once, I would get to the job very early and work furiously to get a true southern exposure done befor the sun hit the wall at about 8:30 AM. A pro painter will follow the shade around the house, often squaring off and returning to a side the next day to continue in the shade.
Another problem as we go into Fall is to stop early enough in the afternoon to allow the paint sufficient time to set before the coolness and possible dew of the evening. If heavy dew forms overnight, "flashing" could affect the sheen of the paint. The homeowner will be able to see where every wall stud is on his house.The studs are warmer than the well insulated wall cavities and therefore do not show dew.
Finally, acrylic paints can take up to a month to fully cure and reach their inherent sheen level. I have personally used the Behr Ultra Flat Exterior paint and noticed that it took several days to fully dull down to its ultimate flat sheen.
Obviously, I am not aware of all the factors which might have taken place. However, I would state that if all variables were kept constant. it is doubtful that any other manufacturers' paint would have given a different result. I have been using Behr products for several years on my own house and have had only positive results. I have brushed and rolled my own Hardi-Plank siding with great results. Fortunately, owning a ranch house, it is fairly easy to maintain proper wet-edge techniques.