Reupholster Emeco Navy 1011 chair?  

You can do it!
I've reupholstered a dozen or so of these chairs. It's pretty easy to do.
The seats are attached to the frame with clips and screws. Once you get the seat off, you'll see that the vinyl is secured on the underside with metal tabs that are just punched out of the seat metal. Pry them up with a slot-head screwdriver just enough to get the vinyl out. They will snap off if stressed too much so just don't bend them up too far.
You'll probably have to replace the foam padding. It's usually dry and crumbly and even if it's not, it's on its way to becoming that way so just get rid of it and prolong the period of time until the next reupholstering.
Cut the new covering a little bigger than necessary. Center it on the seat and slip it under a couple of tabs on one side, tap them down with a hammer, then do the same on the other side after pulling the cover taut. Repeat on the opposite two sides and work your way around, going back and forth and checking to make sure the cover is smooth and taut.
Trim the edges as needed. I found that sometimes the tabs held the fabric better if the edge of the fabric was folded. Other times it had to be cut just to fit under the tab.
Corners can be tricky. Do neat, even tucks and catch as much of the fabric as possible under the tabs. This is where you'll need to trim the edges to just fit. I think adhesive was used on the originals but I never resorted to that.
I had more trouble with the backs. They consist of a metal plate with tabs at top and bottom. The top ones fit into slots in the chair frame. The bottom ones have holes that line up with holes in the frame, through which screws go. The tricky part is getting it all lined up and getting the top tabs jammed in far enough to be able to fit the bottom tabs in. Do not add ANY more bulk to the upholstery than what is there already! I think most of my problems were from adding slightly heavier materials.
And even then I had to use C-clamps to force the back panel into place so that I could get the screws in. The originals were probably assembled with clamps made for that purpose.
Some chairs have back panels with fabric on both sides. The back of the panel is just a piece of thin cardboard with fabric glued to it. The edges are trimmed even with the cardboard. You will probably have to cut a new piece of cardboard for this. Just use the old one as a pattern and make the snips for the tabs exactly where they are in the old piece. Use an acid-free adhesive that will not discolor the fabric over time. I think with leather you can use anything. Rubber cement is good.
On the front side of the back panel, wrap the fabric to the back and clip the curves as needed, just don't go too close to the edge. You'll see how it's done on the original.

more on materials choices
Jeez, I do run on---didn't realize there was a limit on length for these posts. Here's the rest:
I don't think you have to stick to vinyl for reupholstering. I did mine in a Unika Vaev fabric that looks really great with the aluminum. I have also considered leather and the only reason I didn't use it is because I liked the fabric even more. These chairs are a great design but I don't think they're something that has to be true to the original to have any value.
Leather is a great choice. If others are reading and considering redoing these chairs in fabric---I advise strongly to stick to thin, sturdy fabrics with a tight weave. The metal is tough on fabric and there's no room for any bulk at all on the backs. If your backs don't have fabric panels, you have more leeway. I learned this the hard way---I used an inappropriate fabric on five chairs and then had to redo them when it wore out within a couple of years. It was also much harder to work with than the Unika Vaev fabric. Leather would be very easy to work with.

Wow! Thanks spanky...
...you're my hero! You even provided me with some instructions on how to tackle this project...way cool!
I noticed that the upholstered parts of the chair are pretty simply put together and I saw those metal seat tabs when I flipped up the chair to look for labels and how it was constructed etc.
So I thought I might be capable of doing the seat reupholstery myself, but I wanted to ask before I went for it. I'd hate to ruin such a cool chair and I had no idea that repros of the Navy chairs are so pricey...or that Emeco still makes them...or for that matter that my free cool looking metal chair was in fact an aluminum Emeco Navy 1011 semi-upholstered arm chair...I literally just got this chair yesterday so I've been doing research online from the info I found on its underside (I think it is likely a surplus piece from some government institution somewhere).
Any advice on where I should pick up the padding and the leather (i.e. what am I looking for when I ask for the padding and how much leather would it take to do the seat, the back and the arms?)? Are there good sources online and how much should I expect to pay for the materials? I'm in the USA so I'd be most interested in US upholstery sources.
Thanks again y'all. I'm so glad I found this forum.
FYI I live out in the countryside in Virginia and am doing my home in 'country modern' using a lot of found things from the midcentury modern era when I find 'em cheap or free - lots of metals, some red & white enamelware, the odd bit of modern pottery or wooden bowls, etc...no 'log cabin' looks for me in my interiors.

Glad I can help!
I am all for people learning to do things themselves. It's fun (most of the time) and saves money that you can then spend on more cool stuff!
I get leather from kysonleather on ebay (link below). I have gotten three hides from them so far and all have been very nice quailty. I paid around $100-130 per hide with shipping---those are for full hides of 45-55 square feet each. You could easily get by with 15 square feet or even less. If you have to buy a bigger piece, you can always save the excess for the next Emeco chair you rescue from the dump!
As for padding, just get some 1" thick green high density foam from Joann fabrics. They sell it by the foot, I think. They usually have a 40% off coupon in the Sunday papers if you are looking to save money.
On the back, just use some thin batting or 1/2" thick foam but don't wrap it around the edges because that will add too much bulk.
I got all my Goodform chairs (very similar to Emeco) at local auctions but they rarely show up. I have found six in six years. My daughter is a social worker for the state and she says she sees them all the time in government offices! I think the problem is that they last forever and government agencies are not big on replacing furnishings if they are still functional. Someday they'll all decide that they need new chairs and then there'll be a flood of them on the market. I hope. I want another armchair. My hubby is very hard on chairs and I know that he can't do anything to hurt one of these chairs.
Plus, they just look so good!
http://stores.ebay.com/kyson-leather_W0QQssPageNameZstrkQ3amefsQ3amesstQ...

Thanks again spanky...
...I really appreciate all your advice. I am sure it will save me a ton of time, money, effort and aggravation in the reupholstering.
The link to the ebaY seller of the leather hides is also really helpful and so is the info on the type of padding you got at Joann Fabrics. Is there anything I need to know re: the thickness of the leather hides? I am a little worried that I might buy something that is too thick, especially for that back piece and the arms.
I noticed while surfing around on the Internet how similar the Goodform chairs look to the Emecos. I also noticed that practically every TV cop show (such as all 3 Law & Order series) uses the all aluminum Navy side chairs in their interrogation rooms! LOL! I wonder if the shows' prop masters rescue old ones or buy the new reproduction chairs?
Have you ever thought of looking for government surplus auctions in your area for more chairs and such? I am about 2 hours away from Washington DC and I know that all the federal government agencies constantly are dumping things (your tax dollars and mine at work...so maybe my chair wasn't as 'free' as I think it was after all!). I figured this one was cast off by some bureaucrat's office when they upgraded to having computers and somebody probably ditched this diamond in the rough for a lesser quality chair with wheels and all kinds of supposedly ergonomic adjustments...sigh.
I haven't taken a before pic of my chair yet...the after will look something like this but in black
http://www.emeco.net/pdf/1011oo.pdf

My Goodform armchair was the...
My Goodform armchair was the same as that but with a solid back, no spindles. I've done those little upper backs on side chairs, though.
You might find that the armrests are solid vinyl under the fabric. I had one chair with fabric glued to the vinyl--I just took it off and cleaned off the adhesive with paint thinner and put them back on. They were a very dark greenish black. I've seen brown ones, too. And black.
On the leather---Kyson always gives the weight of the hide---I think it's ounces per square foot, maybe. I've gotten medium weight hides that I think would work fine on these chairs. She will send swatches, too, though they're cut from the edges of the hide and might be thicker or thinner than the rest of the hide. But you can get a pretty good idea. The colors vary, too. Not all blacks are the same! I got a bunch of dark browns and one or two had no depth of color and the rest were very rich looking. So it's a good idea to get a few swatches. There's also texture and gloss to consider---pebbled or smooth, matte or low gloss or glossy.
I'll have to keep an eye out for government surplus auctions. I'm in Baltimore so I wouldn't have far to go. I see Goodform & Emeco chairs on tv and movies all the time! In fact, we call them "submarine chairs" in our house because they were used in the submarine scenes in one of the Austin Powers movies.
I also like the big clunky steel Goodform desks when they're stripped and buffed. I got one for $2 and it sat around for a long time until I read up on how much work it would be to strip and buff it. It is no more, sad to say.

Hmmm, I think...
that my arms are like the ones you described...solid and no padding at all. I also think that the back of the chair is either solid or has very little padding to speak of. But it's still a super comfortable chair.
I think what I may do is send Kyson a swatch of the old vinyl so that they can get me leather in the right thickness and weight. I'm not sure what kind of texture I'll want, but I think I'll want a matte or low gloss leather to contrast with that shiny aluminum. The current black vinyl is low gloss and pebbled and has tiny round perforations (like sports car upholstery of the 1960s and 1970s)
I have seen what those stripped and buffed old steel desks and pieces of office furniture look like...if I could get a few pieces with nice lines that at are well build and in decent shape for free or for a cheap price, I think I'd find an auto body shop to do the stripping and buffing. I'm thinking that trying to do that yourself could be very difficult, probably beyond me in terms of the required tools, materials and effort.
What a trip to learn you're in Baltimore! You probably missed out on the great Homicide: Life On The Streets prop sale of 2000 that was open to the public in Baltimore -- I am sure that had you been able to go, you could have scored a couple of chairs and some metal office furniture there...I know they sold off the interrogation room table (complete with a set of attached handcuffs)! Of course since one of my other hobbies is TV & Movie prop & costume collecting (and yes I have a few pieces from Homicide bought straight from the props guys private stashes), I wouldn't have done a thing to anything bought from that kind of source...it would hurt the value to a Movie/TV collector. But anything from an auction like the GSA's or a flea market/yard sale or the dump...well that I guess is okay to tinker around with. I might also mess with anything that came from the Ellis Prop House sale (they went out of business at about the same time Homicide went off the air and they had tons of anonymous period things for sale like old dishes and glasses...it would be hard to attribute anything from them to a specific film or show). There's tons of that stuff on ebay all the time.
What is the Unika Vaev fabric you used like? Also did you take any pics of your Goodforms after you reupholstered them? If you have pics, I'd love to see 'em.
Thanks again spanky!