@ClintC
I covered a lot of this stuff in depth (lot of pages - scan through the parts that don't apply) in this thread:
https://www.arboristsite.com/community/threads/philberts-chain-salvage-challenge.245369/
Couple of key things to keep in mind:
- Removing rust does not replace lost metal. Removing heavy rust leaves a weaker chain.
- Some acids dissolve metal as well as rust, and can actually embrittle the metal. Avoid inorganic acids (hydrochloric, sulfuric, nitric, etc.).
- Some rust removers / methods can also damage the chrome plating on cutters.
- Some acids / treatments will discolor the chains (if that is important).
- Products like Evapo-Rust (WD-40 Rust Remover Soak, et,) work best on surface rust, and require a covered container for best results.
- You need to really clean the chain well first, to remove any loose rust, dirt, grease, oil, etc., so that chemical treatments can reach the rust.
- Some 'seized' links on old chains are due to dried up oil / grease around the rivets, not rust: cleaning them (see referenced thread) and working in some light oil (3-In-One, etc.) will often free up frozen links.
- After cleaning and rust removal, dry and re-lube everything throughly to prevent additional rust.
If I had to choose a simple recommendation it would be:
- clean chain using commercial, water-based degreaser containing sodium hydroxide / lye (home center);
- soak in a weak citric acid solution (Amazon);
- clean off with fine, stainless steel 'scratch' brush (welding supply store);
- dry thoroughly (oven) and re-lube liberally.
Details are in the referenced thread. Please post your results there too!
Philbert