HIDDEN Rust Removal: Chelator vs. Phosphoric Acid
We’re dissolving the rust INSIDE the Volvo P1800 frame rails using chelation — not acid, and getting ready for paint. We talk about why chelators like Rust911 or Evaporust instead of phosphoric acid rust removal.
This is all in a DIY home shop, I run Rust911 in a heated, closed-loop pump to strip oxide from deep cavities, then show the after shots.
Why chelators? They don’t “eat” base metal like acids. They bind oxidized iron (rust) into water-soluble complexes that rinse away, leaving clean, etched steel ready for paint. Rust911 mixes 1 gal 16 gal working solution, is non-toxic, won’t burn concrete if you spill it, and has been the most effective remover I’ve tested for this job.
Critical: fully rinse while still wet. If residue dries, it forms a sticky film and PAINT WILL NOT STICK.
My flash-rust prevention rinse sequence:
1) Dump catch basin → quick hose rinse.
2) Pump clean water through pump, filter, and cavities.
3) Ammonia/water rinse (raise pH 9, no residue after it evaporates).
4) Alcohol flush (displaces water, no residue).
5) Compressed air until bone dry. Let parts sit ~24 h before coating.
Chemistry notes:
• Chelation (think EDTA/gluconates) targets Fe³⁺/Fe²⁺ in rust first; gentle on sound steel.
• Left circulating a long time it can etch bare steel, but much slower than acids.
• Brass nozzles were unaffected; black iron fittings slowly thinned at the threads after ~30 gal of solution.
▶ Watch Part 1 (Cleaning & Paint Removal): [ • HIDDEN Rust Removal: Cleaning ]
▶ Next: Part 3 (Cavity Coating with Moisture-Cured Urethane): [link when live]
Chapters
00:00 Intro
00:42 Starting Point
01:15 Why Rust911
01:51 Chelators vs. Phosphoric Acid
02:22 What's in Rust911
03:03 Chelators will dissolve steel if given enough time
04:07 Protecting the steel
04:51 Lets start pumping
06:30 Whats inside during pumping
07:55 Look again whats inside
05:30 Rinse protocol to prevent flash rust
07:10 Bore-scope results – ready for paint
08:20 Hitting stubborn rust with the spinning flail of death
09:19 Results of spinning flail of death
10:13 Dumping the used Rust911
10:50 Results and how to clean residue
13:20 Next time: painting
Materials used (today):
• Rust911 (1:16 working mix)
• Closed-loop pump + heater + whole-house filter
• Long-reach spray wand with DIY 360° nozzle
• Ammonia/water, isopropyl alcohol, compressed air
• PPE: gloves, eye protection, ventilation
Disclaimers:
• Follow product SDS instructions. Avoid mixing with acids or bleach. Test on a small area first.
• My setup is for educational purposes; use at your own risk.
If this helped, drop a comment with your questions. Like & subscribe so Part 3 finds you.
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