Painting Primer: Their Importance And How many Coat Of Primer Are Needed
The goal of pretty much all painting projects is to finish everything quickly and neatly without wasting too much paint. To reach that goal, many people consider priming the painting surface so the paint could bond easier and last longer than normal. However, you have to know exactly how many coats of primer to use.
Applying too many coats is a waste of effort and money but if you apply too few coats, the surface will not be prepared properly. There are different primers with different characteristics as well which mean you cannot do as you please without risking the paint integrity. Fortunately, this article could provide you with a quick summary of primers along with their applications to help you achieve the desired result.
What is a painting primer?
Generally speaking, a primer is considered to be a type of preparatory coating which improves paint adhesion and its durability. Painting primer also serves as a protection layer for the material being painted since it prevents the growth of mold. In practice, people often use primers when the painting surfaces consist of porous materials (Concrete, wood, …) or not water resistant.
To achieve maximum performance, depending on the primer type and composition, the painter needs to paint over the primer within a certain amount of time. The timeframe could be as short as 24 hours or up to 2 weeks but painting over the primer after this period could cause several performance issues. Most painters usually apply the finish coat of paint before the primer coat cure completely to strengthen the overall adhesion.
Common types of painting primers
Shellac based primers
While shellac based primers are smelly and not exactly easy to use, they are the best when it comes to blocking stains. Whether stains are caused by water, smoke or rust, shellac based primers would take care of them with no problem. These primers could be used to stop tannin bleedings and leaks as well though you need to use them wisely.
Good at filling pores on bare wood, oil-based primers are able to provide the painting surface with a smooth finish without raising grain. They also act as a barrier that keeps the tannins from a couple types of wood to simply bleed through. Oil-based primers release volatile compounds into the surrounding space and you have to use mineral agents to clean.
For most of the time, people tend to use oil-based primer when it comes to unfinished woods, varnished woods, heavy weathered woods and alike. These primers perform rather well on woods that often bleed tannins such as cedar, redwood and others. If needed, you could even apply layers of oil-based primers directly on failing or cracking paint coats.
Latex based primers
Available in low and no-VOC formulas, latex based primers as not as brittle as their oil-based and shellac based counterparts. Products in the category are able to provide the painting surface with a flexible finish which is resistant to cracking. As a result, latex based primers are commonly used on bare softwood but you probably need to conduct a reaction test first to see whether they raise the grain or not.
In most of the case, latex based primers are utilized when the painting surface is drywall because they are capable of spreading the texture evenly. Primers of this type also permit water vapor to pass through so they are not going to peel too easily.
Numbers of primer coats needed.
How many coats of primer on new drywall are needed?
Due to the difference in absorption rate, you could experience an annoying issue called “flashing” when you paint bare drywall. To prevent “flashing”, you should use a minimum of 2 primer coats on new drywalls to be on the safe side. In any case, you should always use high-quality primers from reputable brands such as Benjamin Moore, Zinnser and Muralo.
How many coats of primer on wood are needed?
In the case you paint bare untreated wood, you definitely need to use painting primer due to the porous surface. You need to prime the wood as well if you attempt to dramatically change the color of an already painted wood wall. Generally speaking, to paint the average wooden surface, you have to apply between 1 and 2 coats of high-quality primers along with 2 coats of paints.
How many coats of primer on masonry are needed?
Although primers that are designed for drywall and other surfaces should perform adequately on masonry, it’s advised that you go after masonry oriented products. Oil-based and latex-based primers work well on masonry surfaces, you only need to use 1 coat of primer for most of the time. Of course, you could apply additional coats if you want to but remember to leave the previous coat to dry before applying the next coat.