It's a little bit straighter forward. There are no induction times with Self-Etching primer. There are 1K products that work well for corrosion protection, that are also available in spray cans. So, if you have just a small area and you're wanting to apply such corrosion protection to, a Self-Etching primer in a spray can may be the way to go. Very simple. There are a lot of ways to do this.
If you have a bigger area, let's say bigger than a gold dollar coin, you can mix up some epoxy and use that. If it's smaller than that, you could use a spray can of Self-Etch primer. This is a primer surfacer, so you get your standability with it. But it also has some acid in it, which acts like a Self-Etching primer. DTM can be applied directly to steel and then sanded just like a primer surface.
Important Notes: On epoxies, some have an induction time. Think of it as they have to kind of get to know each other a little bit before they bond.
Good luck! Joined: Feb 10, Posts: Profile Page. Napa carries MS Joined: Feb 1, Posts: Profile Page. We keep a pint can of etch primer mixed up with a small hole in the lid for a acid brush ,to touch up welds and bare metal edges. It also works great if you let drip in between two welded panels after welding for corrosion protection. The brush marks will sand out before you finish prime,as pimpin paint said. Both Spies and PPG had out tests that showed their etch primers out performed epoxies in corrosion protection.
They took chips painted with each and simply put them through weather conditions. Spies etch which used to be available in cans was probably one of the best out there. No matter what tests prove I do not think any paint mfg's recommend any of their products except top coats be left out uncoated where moisture is an issue. The adhesion with an etch primer is way off the chart compared to epoxy. Both have their applications. Etch primers need a barrier between them and final coat. Kind of the the early 80's GM paint failures.
They were trying to save costs by skipping a step. Paint flaked off. Etch primer is almost fogged on with minimal mil build up. Their are preferrences to each product. Probably one of the best all around products for resto work. Joined: Nov 17, Posts: 3, Profile Page. The Sherman-Williams self-etch in a spray can is the best I've ever used.
It's about the only good product that S-W makes. It bites much better than the SEM stuff does. Bugman , Sep 12, Joined: Aug 3, Posts: Profile Page. This is because the primer compound possesses a chemical that is responsible for bonding and etching onto the metal.
The self-etching primers contain a small concentration of phosphoric acid , which chemically burns into the metal. This creates strong adhesion between the future paint topcoat and the existing surface. Since self-etching primers are concocted with low volume solids, they result in low film builds, owing to their thin coats.
Even though they require only a thin coat, they get the job done effectively, by maximizing adhesion. Since they contain zinc phosphate pigments that place a seal, the self-etching primers also boast good protection against corrosion. Note that etch primers also have a very short curing time, when compared to other primers such as latex and epoxy primers.
The metal surface has to be cleaned thoroughly beforehand, using mineral spirits. Then you may choose to sand the surface to make it smooth, using sandpaper that is either wet or dry. Wetting the sandpaper offers a better and smoother finish. Re: Can epoxy primer be sprayed over self - etching primer without ill effects?
It's fine to spray epoxy over self etching. But self etching is mainly to slow down rust before you lay down your filler or other high build primers. Note self etch primer is out of fashion. Most people these days will use an epoxy primer instead which sticks well and is waterproof so you don't need to apply top coat quite so quickly.
Self etch primer was recommended for bare steel, aluminium or GRP, and it won't flake off like a filler primer can. After you remove the rust scales from the metal on your car, you need to apply self etching primer. It's a mix of phosphoric acid and zinc. It's purely a surface coating, and it doesn't stop the rust. It does , however, prevent the rust problem from worsening.
They will stop any rust from adhering to the surface or will kill the rust. Filler primers In most cases, the filler primer or high-build primer is also a urethane product. Because it has the texture to fill pits and imperfections in the sheet metal, an unsanded primer coat would be too rough to paint over without further preparation, which includes a sealing primer.
However, with so many different types of aftermarket paint available lacquer, enamel, urethane, water-based. We recommend that all paint be removed where filler is to be applied. You can coat epoxy or urethane primers over old paint. I personally would not, but you can. It won't craze the paint like spraying laquer on old enamel. But you would really be better off just sanding it down to the factory primer , at least.
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