Self-etching primer is an adhesive that is used to prevent rust on metal surfaces or fiberglass. This type of primer is more beneficial than regular ones due to the chemical that etches on the surface. Simply, it makes the surface callous like sandpaper. However, because of the chemical of self-etching primer, you need to apply a regular primer over it. The reason why, you have to seal the self-etching primer layer unless the acidic bond can react with the paint layer. But what primer to use over self-etching primer? Refer to the details below to know everything in this regard.
What is a Self Etching Primer?
Your full attempt at painting might be pointless if the new paint starts to peel off. To prevent it, the right preparation with a self-etching primer is key. As its name indicates, self-etching primer itself etches the metal surface. As a result, the surface becomes rough and ready for friction.
Thus, this primer aids the new paint to stick properly on the metal surface without peeling off, running, or bubbling. As the active ingredient, it contains methacrylate phosphoric acid ester and zinc, which helps to etch the face and promote the adhesion of the new paint. When the surface is etched, the topcoat can cling well. These characteristics of self-etching primer are beneficial for sheer surfaces and any material that have minor friction.
If you want to paint a metal surface using an enamel-based paint, a self-etching primer is a must. After stripping the old paint thoroughly, the primer should be applied to prepare the surface before applying the new paint layer. It can also prevent rust which is a result of oxidation.
So, in brief, this simple step of applying a self-etching primer can save you money and time because you do not have to experience future repairs.
Why Apply a Primer Over Self-etching Primer?
Let’s clarify why you need another primer to seal a self-etching primer. Most of the manufacturers instruct there is no need for another primer on self-etching primer. Then you can apply the paint without another layer of primer but make sure to check whether your self-etching primer comes from a reliable brand with the necessary standards.
If there is no such advice, use a regular primer over the self-etching primer because the acids in the self-etching primer can interfere with the layers of paint. The zinc of the primer creates a corrosion-resistant barrier. Therefore, you will need to seal it with a regular primer. Otherwise, the active acids splinter or flake the paint layers.
When it comes to the sealing process, regular primer creates an oxidized layer which helps to enhance the passivity of the surface. At the same time, it protects the surface from rust just as the self-etching primer. Some important insulators are included in regular primers, such as titanium, nickel, tantalum, etc. Therefore, the second coat of priming is highly beneficial to make the overall procedure successful.
What Primer to Use Over Self-etching Primer?
After you apply the self-etching primer on the well-cleaned metal surface, you should wait until it completely dries. After that, you have to apply a compatible primer over it.
There are two types of regular primers, urethane primers and epoxy primers. It would be best to use a urethane primer over a self-etching primer. The reason why, it performs as a shield to the paint layer. Due to the oxidized layer that creates the primer, the acids of the self-etching primer cannot interfere with the paint. In addition, the application is easy when compared with epoxy primers.
It would be better to avoid epoxy primers over self-etching primers because it is not powerful enough to act as a protective coating. The acids do not let the epoxy cure because there is a high moisture content than urethane primers.
Most of the time, the epoxy layer can be dried by the acids in a self-etching primer. In addition, the surface might blister. Thus, you will not be able to get a smooth paint surface. However, you can check the instruction of the manufacturer. If there is a recommendation to use epoxy primer over self-etching primer, it will work.
However, in general, urethane primers are the best option you can go for because they can overcome the issue of self-etching primers and provide extra protection for the surface. If you miss this step, the acids of self-etching primer can seep into the paint layer, so make sure to apply a urethane primer.
If the manufacturer recommends directly applying the paint on it, there is no problem, do it. But remember, some kinds of paints can only be applied on metal surfaces that are specially designed to apply on metal, steel, and aluminium.
Can You Use a Self Etching Primer Over the Paint?
If you have a metal surface or fibreglass to repaint, there are some essential steps to follow. You cannot directly apply self-etching primer over the old paint.
Indeed, it will be pointless because the acids of the self-etching primer are unable to create the powerful chemical bond upon an old paint, and the zinc in it will not form a non-corrosive barrier. Instead, the acids gradually spoil the paint underneath it. As a result, you will see a bumpy metal surface, although you repaint it.
To avoid the above issues, you have to prepare the surface before applying a self-etching primer. Start preparing your metal surface or fiberglass with a proper cleaning, so wipe all the dirt and debris thoroughly.
Secondly, you need low-grit sandpaper to sand the surface. Although the surface is not too bumpy, it would be better to sand the surface before coating anything. It will make the surface even so you can apply the self-etching primer easily.
Next, you have to wipe the surface for the second time since there might be dust after sanding the surface. You can use a mineral spirit here. But make sure to dry the surface well before applying the self-etching primer.
More About What Happens If You Paint Over Self-etching Primer?
Video Credits – Tech WHYS YouTube Channel
Recommended For You:
Applying the Right Primer Over Self-Etching Primer
Enhancing Your Project with Tinted Kilz Primer