I have a fender and inner fender that have significant amounts of surface rust. So I am looking for the best way to remove the rust before priming and painting... (it's not Mopar but don't tell anyone, hydrated iron oxide is the same compound for all manufacturers)

I've got 5 gals of Evaporust but nothing big enough to put the parts in and keep them wet. Also available are: angle grinder with flap disc; wire cup brush; air sander with pad and 80-grit discs. The inner fender appears to be 16-ga (.050) and I'm concerned that blasting would warp it.

Suggestions please?

Sandpaper and those black 3M paint stripping discs in a drill.

I would knock the heavy rust off with a brush . Then use the evaporust by putting it in a cheap plastic little kids swimming pool . You could tilt it for more depth , move the part around , keep it wet by brushing / splashing it on in the pool . I have kept the part wet using scotch brite pad . I love the evaporust ! Non toxic mild on bare hands !

Bag it. You're familiar with marinating meat right? This is just really tough piece of meat.

I would run a scraper or wire brush over it first, then bag it and evaporust it.

Blasting would be ok as this isn't an exposed panel, warping wouldn't be noticeable.

I think you'll find that evapo rust works on small parts that are not. heavily rusted. I've tried soaking, pumped stream and maintaining temps over 70* for both the solution and the part. Removes rust but not fast enough or completely. Forgot to mention the price$$$. I did a back to back evaporust and phosphoric acid(that you can get from Lowes). I cleaned the parts(removal of any dirt/grease) and placed them completely submerged and covered in the appropriate products. For the record, phosphoric acid only removes rust and not the metal. Rusted metal was the same piece cut down the middle. 12 hrs later, evaporust removed surface rust and did not begin to start on some the heavier areas. Phosphoric acid removed the surface rust and was working on the heavier areas. After the 12hrs, I used a green scotchbrite and SS wire brush 1/2 X 1" and scrubbed all the surfaces. More rust came off the acid bath than the evapo bath. 24 hrs later, heavy rusted areas were mostly rust free in the acid bath and evapo was slowly work and the solution seemed to be very saturated with iron oxide. The phosphoric acid costed $18.97, the Evapo $43.99. I don't use evapo anymore.

Thanks everyone. I've used Evaporust before (that's why I bought 5 gal when Amazon had a sale)... but I agree, it is slow especially on heavy rust and cooler temps. Good idea on the bagging, but I'd have to keep turning and agitating it too.

I ended up sanding it with a DA and 40-grit discs, and a pistol-grip sander with a flap disc for the tighter and more curved areas. I tried to stay upwind, and blow off the rust frequently, but I can still taste it...

I also remade the rusted piece, welded it in, cleaned everything and gave it two coats of Rustoleum Rusty Metal Primer, inside and out. Now trying to decide whether to paint the wheel side or just use undercoating on that side (we have lots of gravel roads around here).

The dent is there because it clears the a/c bracket that came from a car with the same engine.