Most modern costumers who are trying to be as historically accurate as possible use cane/reed. I’ve got an issue with this, and while I posted briefly about boning here, but I realized that I had most of the discussion on LJ.
Here’s my logic: in the period, whalebone was THE preferred boning. Yes, cane/reed were used, but they were considered a substandard material and generally used on homemade (ie not professionally made) stays. Ask anyone who’s made a corset with reed/cane and had it break on them why!
The best source is: Dorsey, S.. “For neatness, true fitting, shape and fashion”: The craft and consumption of stays in eighteenth century America. M.A. diss., University of Delaware. Anyone with access to a university library can get a PDF copy of this thesis from the database ProQuest Dissertations & Theses.
Dorsey writes: “The most important part, however, were the “stays” themselves: the garments’ main structural support. The rigid inserts were made from a variety of materials such as wood, thread, and whalebone. Whalebone, otherwise known as baleen, was the most common material and the most expensive. Cheaper alternatives included the use of split wood, steel, pack-thread, and pasteboard.(100) Of those, most pairs of surviving American non-baleen stays are boned with wood. The wooden inserts appear to be made out of riven hardwoods (Figures 21 a and b). Wood is also particularly susceptible to fluctuations in humidity and stress. Over time wood becomes brittle and snaps in two at the stress points, usually on the curve of stay tabs. For this reason it was not an ideal material to use and is typically seen on stays made by an amateur.(101) “Packthread” stays are seen in American stay maker advertisements, where they are also noted to have been imported to America. Packthread is a strong cord or twine made of coarse flax or hemp plied together. Baldwin and Hyer, for example, wrote “that they make Stays with Whale-Bone, which are far preferable for Ease and Genteelness, to those imported from England, that are made of Packthread.”(102) Indeed, whalebone was seen as the superior material in stay making.(103)
(100) Rushes are known to have been used in seventeenth-century stays and were likely used in the eighteenth century. However, in the survey of American stays conducted for this thesis, no pairs were found to exhibit them. Some historians note that bone and ivory were used, but as Mark Hutter pointed out, they would have been too rigid and brittle to function as anything else other than busks. Mark Hutter, email with author, 24 March 2008.
(101) There are no advertisements for wooden stays, it is more likely that they were made by persons who could not afford whalebone (baleen) or the services of a professional stay-maker. Haughland, “Common Cotton,” 3.
(102) Baldwin and Hyer, New York Mercury (New York, NY) 20 May 1765.
(103) Sorge-English, ’29 Doz and 11 Best Cutt Hone’, 30.”
(Bolding is mine)
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Norah Waugh in Corsets & Crinolines goes far less into this topic, but she does say briefly, in her appendix on whalebone: “When stiffened bodies and farthingales appeared in the sixteenth century it could not have been long before the superiority of whalebone over wood and cane supports brought it into use wherever available” (168).
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Lynne Sorge-English has two articles that are related & interesting. She mentions that whalebone was by far the most popular boning in the 18th c. in: Lynne Sorge-English, “’29 Doz and II Best Cutt Bone': The Trade in Whalebone and Stays in Eighteenth-Century London.” Textile History v. 36 no. 1 (may 2005): 20-45. The other article, which doesn’t go into this topic but is still very interesting, is: Lynn Sorge, “Eighteenth-Century Stays: Their Origins and Creators.” Costume 32 (1998): 18-32. She’s now come out with a book that I haven’t yet read, but is on my wishlist: Stays and Body Image in London: The Staymaking Trade, 1680-1810 (The Body, Gender and Culture)
(full disclosure: I’m an Amazon Associate and buying from that link will send me a couple of cents).
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So to my logic, yes reed/cane is an historically accurate material that we can still get, while whalebone is not something we can get ethically or practically. Since I was trying to make a pair of stays appropriate to an upper class woman, I needed an equivalent to whalebone, not the boning material that would have been used in substandard stays. The properties of whalebone that made it so popular for corsetry was the fact that you could cut it to any width/length/thickness, and the fact that it molds to the body over time.
Now, we come to our modern boning products, most of which are accurate to the Edwardian era or sometime in the 20th century. For a good rundown, I recommend Sarah’s “Various Boning Options for Historical Corsetry” and Jenny-Rose’s “A Word on Boning.”
The main boning type that neither of them discuss is the plastic boning made by Wissner, a German company and so hence often called “German plastic boning.” I had heard good things about this boning material — that it is very comparable to whalebone in terms of support and its ability to mold to the figure — so I decided to try it out, and used it on the handsewn (green) version of my stays.
So, the report!
In the past I have used spring steel (aka white steel), spiral steel, and the crappy plastic boning sold at Joann’s (don’t even get me started). I haven’t used cable ties or cane/reed or any of the other strange and wonderful things you can use as boning! Now that I’ve made up my stays and worn them for over a a year, I can say that the German plastic gives you way more support than the crappy Joann’s plastic, more support than the spiral, and a little bit less support (but not much) than spring steel. In my stays I decided to reinforce things with spring steel at the CF and CB, as well as at 3 points throughout the front piece. I’m currently working on a corset (more on that soon) and just tried it out with only spring steel at the CF and CB, and I felt like I did want one or two more spring steel bones in front.

Bending spring steel (L) and German plastic (R) -- the German plastic requires less force to bend
The best part about the German plastic is it DOES mold to your form. Here’s one half of my 1780s stays laid flat on my cutting table. You can see how the tabs have formed themselves to the shape of my hips:

In addition to its support qualities, you can buy German plastic boning in a number of widths. It’s sold in thicknesses from 13 to 5 millimeters (1/2″, .4″, 1/4″, and 3/8″) at the place I buy from (more on this in a sec). This means you can make corsets with finer boning channels, like this gorgeous pair of stays made by The Staymaker. Here’s a photo of some of the boning I have on hand:

From L to R: spring steel .5", German plastic .5", spring steel 3/8", spring steel 1/4", German plastic 1/4", German plastic 3/8", crappy Joann's boning 3/8"
It is a bit thicker than spring steel, so you’ll want to add a little bit (maybe 1/8″?) to your boning channels to accomodate this.

L to R: spring steel 1/2", German plastic 1/2"

L to R: spring steel 1/4", German plastic 1/4", German plastic 3/8", crappy Joann's plastic 3/8"
The German plastic comes in rolls, which means you can cut it to size, and unlike steel you don’t have to use complex tools or dip the ends to cut it (a pair of scissors works just fine).
In terms of where to buy it, the main source in the US (and where I order from) is Vogue Fabrics. They sell all the various widths, and you can buy in rolls of 25 meters or 100 meters. Farthingale’s Canada also sells it, but their website is so annoying I’ve never bothered to figure out if it’s more/less expensive. In the UK, you can buy it from Vena Cava Designs.