<div dir="ltr">I often use phosphoric acid to clean and de-rust fuel tanks before coating with an epoxy sealer. I find it works great for getting ALL that last rust out and etching the surface nicely. As I am sure you recall, you must clean and paint immediately. Steel etched with acid will be highly susceptible to corrosion if not coated right away. I like to clean with water to neutralize the acid then immediately rinse with solvent to get rid of the water. Denatured alcohol works great to dry the water, but might not be compatible with all types of primer. <br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Nov 13, 2022 at 3:31 PM Jim Stone <<a href="mailto:1789alpine@gmail.com">1789alpine@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="overflow-wrap: break-word;">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><br></div><div>I have a gallon of this sitting around: <a href="https://www.amazon.com/Klean-Strip-GKPA30220-Gallon-Phosphoric/dp/B00945D15I" target="_blank">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="color:rgb(34,34,34);font-family:"Helvetica Neue",Helvetica,Arial">Rust-Oleum Rust Reformer (</span><a href="https://www.rustoleum.com/product-catalog/consumer-brands/auto/removers-and-chemicals/rust-reformer-spray/" target="_blank">https://www.rustoleum.com/product-catalog/consumer-brands/auto/removers-and-chemicals/rust-reformer-spray/</a>) and call it a day?</div></div>_______________________________________________<br>
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