How can the overlap marks be avoided during the painting process?

Try not to paint an extensive area at one time. The overlap phenomenon occurs when the fresh sections of paint begin to dry before you start painting the adjacent area. 

When touching up a wall painted with semi-gloss water base paint, ¿how can the shiners, scratches and outlines be avoided without repainting the entire wall? 

First, repair the defects or imperfections in the wall. Sand the area around the area already repaired and then apply a primer type drywall.  For painting, reduce with water some of the original paint in 25%. Apply this paint from the center of the area repaired, using the original application method and start to work toward the perimeter. During the retouch process, minimize the difference between the recently applied paint film and the general appearance of the wall. If the area repaired is still visible, paint the entire wall. 

Which is the best method to carry out a retouch?

To obtain acceptable results, it is important to apply the paint in the retouch process under the same method and the same tools with which the original application was carried out, in order to avoid difference in texture and shine. Make sure to use the same paint that you use in the original application, but reduced with water in 25-50%.  Apply a thin coat. It is also advisable to apply the retouch paint under similar conditions of temperature and humidity as the original application. 

If I am going to paint the interior of a 100m2 house, ¿what is the advantage of using air sprayer vs brush vs roller?

The decision to use a specific tool depends on the availability of space to work, that is, if the space has too much objects and people or, conversely, the place is inhabited and with few objects. Under this consideration, if the house is “empty”, the air sprayer is the fastest tool for the application of the paint. If you have to move or to cover furniture or tape windows, the process becomes larger. With the air sprayer you will have a large quantity of painting that “bounces-off” and falls to the floor. In this case, everything that is not going to be painted must be covered. In the case of the roller, to cover many areas or objects is not required. Additionally, painting with roller can be performed by several people at the same time, reducing the time of for paint installation. Use roller for large areas and brush for small areas. 

What happens to paint if it is applied in conditions of high temperature and moisture?

High temperatures (50°C or more) can cause paint film dries before it adheres correctly to the surface. This phenomenon can represent a risk of flaking or peeling in the future. 

Why is it common that dark colors no touch up, even when the original paint is used and the touching up process is done few days after the original application?

Dark or deep colors are made with pigments that need to stay dispersed in the paint during application. If the painting is not stirred continuously, it could be applying different concentrations of pigment at different times during the application. As a result, when you are going to retouch with a recently agitated paint, you could put more or less pigment in the wall and then the difference in color is seen. When retouch painted surfaces, it is recommended to use the same paint that was used in the original application, but diluting the paint with water in 25-50%. This prevents the film paint accumulates, which is one of the causes in difference of appearance. At the same time, the retouch paint must be applied with the same tool (brush or roller) you used to apply the original application. This prevents differences in texture, which makes the retouches areas more visible. 

What does cause the apparition of paint "bands"?

The phenomenon of paint "bands" appears with more frequency as a stripe at the adjacent edges between the wall and the ceiling. This phenomenon occurs when the wall is painted with roller and “cut-in” with brush. The application with roller and with brush generates a difference in texture. This effect is corrected by applying another coat of paint, but maintaining a wet edge in the areas where the cut-in is done. 

Can mildew be permanently prevented?

Under certain circumstances, is not possible. Water base paints are formulated to prevent mildew growth. But, if moisture condition, in the place where the paint is applied, is high and permanent, the mildew tends to appear. In this case, is recommended to use an additive that acts on the film of the paint, preventing mildew growth.   

Which it is the best way to paint exterior brick? What techniques give the brick a unique texture or finish?

First, let new brick exposed to weather for at least one year before painting it.  It is good idea to wash the brick with pressurized water in order to remove dust or deposits embedded in the pores of the brick. Allow the brick to dry perfectly for several days before painting. Make sure the brick is completely clean. The more used option, is the application of a coat of concrete especially if the brick is very porous; concrete must dry and harder at least 1 month; after concrete has hardened, is recommended to apply a plaster stucco for exteriors and, finally, paint with the final finish product. 

How long should it wait to apply paint over new stucco?

Present technologies in formulation of stuccoes let them to harden quickly. A prudential time of at least 72 hours for drying and hardened is recommended.  After this time, the surface can be painted with final finis paint. 

Is it advisable to apply enamel type paint over a water base paint?

No, it is not. Enamel type paints harden and become brittle with the time, but the latex paint (water base) underneath remains flexible. As time passes, the latex film keeps flexible and moves with the expansion and contraction of the substrate more than enamel film in outer can do. This phenomenon compromises the adhesion of the film enamel and can cause its peel or flaking in long-term. 

There is a discussion about the best method to paint the exterior of a house.  Some people think is better to use a brush; other consider that the application with paint sprayer and retouch with brush is better, while others consider that application only with paint sprayer gives the best finished.  Which is the best method?

Painting with paint sprayer usually gets more paint on the surface in relation to the application with brush. Properly used – keeping the gun 30 cm (approx.) from the surface, at an angle of 90° and with the recommended final film thickness - paint sprayer is the most efficient way to paint large surfaces in exteriors. The application with brush implies more time. For windows and frameworks, it is necessary to use brush. 

Which is the best tool, between brush and roller, to apply paint in exteriors?

The selection of the tool, brush or roller, depends on how wide the surface is.  For very wide surfaces, it is advisable the use of roller instead of brush. For small areas the use of the brush is more advised.  

Is it always not advisable to paint in direct sunlight?

It is better avoid painting with the direct sunlight, especially in very hot periods.  The heat from the solar rays cause the paint dries so quickly, which can lead to several problems like marks of the brush or roller, overlap marks inadequate adhesion, etc.  Paint in different sections of the house in order to avoid direct sunlight. 

How long after it rains should I wait to paint?

It depends specifically on how wet the surface is. Cement or brick surfaces tend to absorb more moisture from a drizzle than a metallic or painted surface. It is advisable to wait at least one day after a strong drizzle. However, make sure the surface is completely dry before painting. 

What usually causes paint to fail prematurely in its performance?

The most frequent causes related to premature failures in the performance of the paint are: inadequate surface preparation; inadequate paint installation; inadequate product preparation; inadequate environmental conditions during the installation.  That’s why the importance to follow carefully the recommendations from the manufacturer at the time you use any product.