<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">The last time I painted a car was in the 1980’s, which I’m pretty sure is before the invention of self-etching primer. If it was around then, I didn’t know about it. I learned everything I knew from reading DIY books and used a phosphoric acid solution to etch bare metal before priming. I haven’t heard of anyone doing that anymore, but need to prime a trunk lid and am thinking it might be worth a phosphoric acid wash first. I had the lid dipped about 10 years ago and it was left untreated all this time. (Not by me, but that is a different and longer story.) The lid has been sitting on the car and the underside still looks nearly perfect. The car with has always been garaged but the top had a light coating of rust. I’ve removed that now but there are some pits here and there (probably from before the dipping) and I would like to be 100% sure it is rust free before priming it. <div class=""><br class=""></div><div class="">I have a gallon of this sitting around: <a href="https://www.amazon.com/Klean-Strip-GKPA30220-Gallon-Phosphoric/dp/B00945D15I" class="">https://www.amazon.com/Klean-Strip-GKPA30220-Gallon-Phosphoric/dp/B00945D15I</a> Is there any reason not to wash the surface with a diluted solution before priming? Or, should I just use something like <span style="caret-color: rgb(34, 34, 34); color: rgb(34, 34, 34); font-family: "Helvetica Neue", Helvetica, Arial;" class="">Rust-Oleum Rust Reformer (</span><a href="https://www.rustoleum.com/product-catalog/consumer-brands/auto/removers-and-chemicals/rust-reformer-spray/" class="">https://www.rustoleum.com/product-catalog/consumer-brands/auto/removers-and-chemicals/rust-reformer-spray/</a>) and call it a day?</div></body></html>