I bought a Hawthorne (Montgomery Ward) Hercules 3 speed after initially passing it over because of flaking chrome on the rear wheel which is a 26 x 1 3/8 rim laced to a 40 hole S-A AW 3 speed. I thought I had a donor and bought the bike but it was a Schwinn with the 597 size wheels, which rub the fenders on the Hercules. I decided to try a brass brush and a dremel to tackle the rust, and it looks like I'm down to bare steel on the flaking chrome plate.

Steel appears duller than surviving chrome along tire bead.

I might be able to snag a donor set, presumably newer and still steel, but I'd like to try to keep the set, because they're B.C.C. 26 x 1 ⅜ rims.

"26x1⅜ B.C.C. - F

I know, I know. Alloy rims are better in about every way. I've always liked the look of chrome, and I'd like to spend time rather than money. I could use Fluid Film lanolin spray to keep the rust at bay, or Ospho to stabilize it (and likely turn it a metallic black). If you tried this, how did it work out for you?

Electrolysis will work a treat on these. Google electrolytic rust removal (I would post a link but I don't have enough posts yet).
all you need is a container to dunk your rusty object (for a wheel I did recently I used one of those flexible builders buckets, just moved the rim round once the section that was immersed in the solution was clean), fill the container with solution (water and bicarbonate of soda works for me) - then attach lowish DC current (I'm using a 14v wall brick type power supply from some long defunct appliance) to the item (-ve lead) and the +ve lead to a chunk of iron or steel. Leave to bubble. The joy of this approach is that nothing but rust is removed. And your arm doesn't ache after hours of scrubbing. After a few hours I wipe / brush the residue away and rinse. Definitely worth looking into.

Sorry to burst your bubble, but there is no way to 'restore' rusted chrome short of having the parts professionally refinished. Be warned: Chrome plating is very expensive. Unless we're talking about some rare collector model, I would not even consider having bicycle parts re-chromed.

Safety first... And those aren't safe. Get some polished Sun CR-18's, then you can polish those to a mirror shine and be safe.
I have the same issue on a Raleigh Sports I want to rehab. You can salvage chrome up to a point, after that the base metal is gone along with the chrome.

From what I remember, useing electrolysis on chromed parts is bad juju. Carcinogenics are produced, and the waste water is super fund material.

Yeah, the chrome is gone, at least on the top picture. The rust underneath could be removed chemically (or by electrolysis), but in the end there will be bare steel with little bits of chrome remnants randomly stuck here or there. IMO the only choice here is to fully restore by taking it to a chromer, or sandblasting them and finishing with primer and paint instead. I the rim isn't something crazy rare, it makes more economic sense to rebuild the wheels with new rims.

IME the rust replacers make everything look like a medieval farm implement. Not the right look for a bicycle.

The bottom picture looks salvageable. OTOH if if is the mate of the first one then maybe not... I suggest treating it with a chemical rust remover like evaporust, and then polishing with chrome polish. It may turn out surprisingly well. A few coats of wax should keep rust mostly at bay if it's stored inside.

Some 26 x 1 3/8" EA3 (290) vintage replacement rims should be reasonably easy to find. Gazillions were made. If you get some new alloy CR18 rims, they could be hand polished until they are as bright as chrome. Just takes elbow grease.

Thanks for the input. Looks like I'll try to snag a donor wheel.

The bottom picture is the other side of the rim. Same wheel. The corrosion is bad on ⅛th of the wheel, while the rest is salvageable. Since I'm not going to paint it, it's probably prudent to go with the donor wheels.

Nothing is burst, I was only hoping to use these wheels. I haven't even seen if the nipples can be turned! I guess I'll take the hub and junk the rim and spokes.
... After I refurbish the hub.
S-A AW hubs from the 60's must be worth something.

Not really a lot of value except for the fact they remain steadfastly reliable when used.
I've probably got a very nice, maybe NOS, EA3 40 hole rim if you need to go down that road. PM if you'd like.

No, that's exactly the hub I have. I'd be looking to sell one.

Sorry I thought you wanted to rebuild your hub on another rim. Good luck.

I've read that S-A AW were top quality until the mid '60s, then quality went downhill.

Been there, done that. The cost quickly approaches a brand new wheel. Completed sales for 50s and 60s 40 hole hubs, especially refurbished, seem to be in the $10-20 range. Not terrible if I'm refurbishing these anyway.

I"d say get the surface rust off, get something to seal the exposed metal, then ride them, patina and all, until you start popping spokes. Maybe just limit the 60 MPH descents.

Why should I take advice from a guy that looks like Ted Bundy?
😄
edited to say that a squashed tiny Carl Sagan resembles Ted Bundy.

The spoke nipples turn freely. I guess that's what brass nipples and zinc-coated spokes are good for? I'm not going to worry much about the brake track, you're not supposed to brake with the back wheel much anyway.

Just make sure there's still enough sound steel under that bubbling chrome and rust.

Here's the inside of the most corroded area:

Not bad.

This one looks the worst.

degan 's advice doesn't seem too crazy (and I have yet to hit 60 mph on a downhill descent on anything with two wheels). I'll update as this progresses.

The wheel is likely sound, but ugly. The rest of the bike doesn't look that great either, but I hope to clean it up enough to get a few heads to turn.

To end the thread, I'll just say that I didn't complete this, and wrote the wheelset off after finding a younger set of chromed 26" wheels with a SA 3 speed hub. I got into the front hub and saw that the cones were really pitted, and the replacement cones sold for too much. Bad rims and bad hubs = scrap. I'll keep the SA 3 speed hub from the original set, though I've been using it for parts. I'll gladly accept a low gear pawl, pin, and spring, and a right side windowed axle nut, if anyone has a few laying around!