No, it really isn't what pro's ues for a car that will sit waiting for completion. They topcoat that product very soon if they use etch or they seal the job in epoxy. It surely don't sit out in the rain. Etch is porous. It lets rust form on the metal beneath if it sets wet for too long. And you can't even see the rust beneath until later when it causes paint failure. We have all seen this. Rust pushes off the etch primer on projects set out in the weather. It is a great product for metal that has minor questionable rust flash, (if flash rust is very minor, maybe a color cast on the metal) but it won't hold out rust when a car sits in the weather or sits in humidity waiting completion. I've bought a few panels covered with etch and I always bring them back down to bare steel, because this product, as good as it is, is porous and it won't hold out water for a stored project.
Additionally, this product is unsatisfactory over body fillers, old paint, or any other substrate other than bare steel. It is unsuited over any OEM finish, even the tiny amounts you might have missed while preparing the car. On the other hand, epoxy is suited over dman near any clean substrate that is solid. It won't peel back off of a minor glitch of OEM finish left behind and it works over fillers just fine.
Chemical stripping of etch primed parts I have bought shows rust forming on panels covered with etch. Some you see rust bleeding though on lots of "driver" projects that are work in progress. You won't find any reputable restoration shop using etch for projects that encounter months of delays. Etch is a fine product for adhesion to bare steel when it receives a prompt refinish. But it doesn't hold out moisture over the long term anywhere like epoxy will. Use over anything other than bare steel is not supported in the product data sheet. A project that has no OEM finish remaining anywhere would be rare, perhaps dipped in chemicals or media blasted like my own project.
Since we are posting product photos, I'll post the only primer trust my project with.
