Self etching vs epoxy primer

Good morning! I am just looking for a quick basic answer
here. What is the difference between the two? Which should I
be using on my small parts as I clean? Most of my parts I
have cleaned of all grease, oil, and old paint. It just might be a
good year before I paint. I want to protect the parts and prep
for paint in the future. I have been using Rust-oleum self
etching in a rattle can. As always, thank you for your time.

I like the self etching for parts that were formerly oily and greasy even though they are well cleaned I've had adhesion problems with epoxy on those type of parts.

The self etching primer is easier to use but the epoxy primer is more durable. With the etching primer if the paint is scratched down to the metal rust will form and spread out under the paint. With epoxy the rust will be isolated to the scratch. The downside to epoxy primer is it has a recoat window usually around eight hours. This means you would have to either apply the topcoat or apply a filler primer within that window or apply another coat of epoxy primer at a later date.

Thanks! So if I am understanding you correctly, the parts I am self etching today should be ready for top coat even if it is six weeks from now?

Yes, there isn't a recoat window on the self etching primer. You could recoat them anywhere from an hour to years from now.

Hate to go digging up old threads, but I'm just scanning through things a bit. Some of the advice given in this thread is simply not good or untrue.

Etching primers have some amount of acidity to them and thus "etch" into the surface of the metal. They dry fairly fast and are thus still in a lot of use today in the repair industry, however they are considered to be 'old technology.'

Etching primers a lot of the time aren't even recommended to be topcoated and those I have used certainly DO have a recoat window (8 hours, for instance). They also are more likely to have chromates in them which are bad news for health, especially for a hobbyist that may not have clean air supply.

Epoxy is more durable, I can agree with this statement. It is no more difficult to use either. I've heard people say it can be more finicky on a contaminated surface, but I've apparently been doing a good job with surface prep because I have yet to see this issue.

The epoxies which I have used have a 24 hour recoat window.

To the OP - specifics are either on the label or in a TDS (technical data sheet) you can usually find online by punching in the brand/part number of the product you have. It will tell you recoat times and surface prep info.

If you have used etching primer on some parts and are planning to top coat them soon, I would strongly recommend you scuff the surface and apply some form of sealer primer to them before painting.