As I've written about previously, much of the symbolism we associate with the KKK was the creation of fiction, not coming to us not from the original Klan of the immediate post-Civil War era, but rather consciously adopted by the Second Klan in the early 20th century in emulation of the romanticized and ahistorical portrayal in Thomas F. Dixon, Jr.'s The Clansman: A Historical Romance of the Ku Klux Klan, which was in turn adopted as the early film epic The Birth of a Nation by D.W. Griffith.
Now, to be sure, unlike the burning cross which I discuss in the linked answer, the constuming wasn't created entirely out of whole cloth. The original Klan absolutely did dress in elaborate disguises, although there is little credence of the idea that they honestly believed doing to would cause the Freedmen they terrorized to believe them to be otherworldly. To be sure, it added to the fear, no doubt, but ascribing such simplistic superstitions gives credence to the stories passed along by the Klan themselves rather than its victims.
In part the disguises of course were simply for practical purposes, to prevent identification during the commission of their crimes. It was also performative, however, and leaned into traditions that would have been understood by the public at the time and which they hoped would influence how other white persons interpreted their actions. In her study of the First Klan, Elaine Parsons sums up their purpose in this regards thusly:
As a conquered people trying to determine how far they could reassert white Democratic political and economic control, wary that northerners would suppress any direct display of organized violence, Ku-Klux had everything to gain by encouraging northerners to read their attacks as theatrical rather than political or military. By couching their attacks within often-elaborate performances derived both from mid-nineteenth-century commercial popular culture and from the long folk tradition of “rough music” or charivari, Ku-Klux adopted a time- tested strategy of the weak. As James Scott has argued, “Actual rebels mimic carnival—they dress as women or mask themselves when breaking machinery or making political demands; their threats use the features and symbolism of carnival” to “conceal their intentions” from those in power, who delay their response while attempting to determine whether the rebels are “playing or in earnest.”
The costumes were hardly uniform, however, and while some wore white, and some wore pointed hoods, but it was hardly a standard uniform, and the costumes often diverged quite far from such a description, and could be quite elaborate, such as this mask which was used by John Campbell Van Hook, Jr., a former Confederate Colonel, which well speaks to the carnival feel that many Klansmen chose to emulate. Horns were very popular, as were fake beards and animal inspired accoutrements, and a popular sentiment expressed was that they were 'the ghosts of the Confederate dead', although it ought to again be noted this was a self-identification, and we ought not give credence to victimized African-Americans widley believing that to be the case. Similar can be said for the self-identification as 'coming from hell'.
So in short, the main takeaway here as regards the First Klan is that their manner of dress should be understood as costuming. Although some bands sought uniformity, even in a single group wide diversity could be found. In comparison, the Second Klan did not dress in costumes but rather in uniforms, which the well known image of the white robes and pointed mask being the expected dress of most members. While some descriptions, and surviving examples, of dress from the First Klan resembled this, it simply wasn't all that common, and there was wide from for individuality.
In the Second Klan though, there was a strong sense of hierarchy and order that precluded such forms of self-expression, and the wearing of standardized uniforms was almost to be expected - Klan literature made dubious claims about how it made everyone equal in the brotherhood. And what better than the then current pop-culture image of the First Klan? The simple white, hooded robe - the white a symbol of the racial, sexual, and religious purity that they sought to uphold - was standard for all basic members, while higher officers were given more colorful and decorated robes as befit their rank. To be sure, there is also the amusing fact behind the whole matter, namely that it wasn't just that everyone had to dress the same, but they had to dress exactly the same, with the robes manufactured by Edward Young Clarke, a early leader of the group, and sold at significant mark-up for a hefty profit. In any case though, the hidden identity and costuming still carried with in a performative aspect as it had with the First, but also in a much more constrained and controlled manner. An exoticism but only to a limit.
Internally the Klan lore attached a great depth of meaning to the robes, just as they did to the wide array of ritual and symbolism that characterized the Klan. The whiteness especially was steeped in the various pillars of Klanhood, perhaps most obviously being tied to the racial ideals that the Klan advances, but it also carried with it deep religious symbolism as well, in line with the Klan's self-image as defenders of the Protestant faith. The white robe was a sign of their righteous cause, and at least one affiliated Reverand took that even further in his declaration that:
I think Jesus would have worn a robe such as they [the Klan] use, but because He did not wear a robe a mob came and took Him and crucified Him.
Again though, none of this can be attached to the First Klan, and indeed the connections between the two are tenuous. The similarities are not simple coincidence, but are something of a game of telephone. If we look at Dixon's novel, for instance, he describes the garb of his fictional Klan at several points, such as this passage:
The men, who gathered in the woods, dismounted, removed their saddles, and from the folds of the blankets took a white disguise for horse and man. In a moment it was fitted on each horse, with buckles at the throat, breast, and tail, and the saddles replaced. The white robe for the man was made in the form of an ulster overcoat with cape, the skirt extending to the top of the shoes. From the red belt at the waist were swung two revolvers which had been concealed in their pockets. On each man's breast was a scarlet circle within which shone a white cross. The same scarlet circle and cross appeared on the horse's breast, while on his flanks flamed the three red mystic letters, K. K. K. Each man wore a white cap, from the edges of which fell a piece of cloth extending to the shoulders. Beneath the visor was an opening for the eyes and lower down one for the mouth. On the front of the caps of two of the men appeared the red wings of a hawk as the ensign of rank. From the top of each cap rose eighteen inches high a single spike held erect by a twisted wire. The disguises for man and horse were made of cheap unbleached domestic and weighed less than three pounds.
It is much more clearly a description of the Klan of the future than that of the past! And that, again, is no mistake, since as we return to where we started, while the First Klan the inspiration for Dixon's novel, there is little in his work of fiction that reflects the reality of the domestic terrorist organization. The story of romantic freedom fighters was popular, but is best remembered for its portrayal on screen, which in turn inspired the reforming of the KKK. in 1915. And thus the Second Klan in many ways wasn't a reforming of the First, but rather a bringing to life a false image from a work of fiction that had never existed in the first place. Although carrying with it much of the same strains of racism and white supremacy, even if carried out in very different manners, they were taking cues from pop culture, not history.
Sources
Baker, Kelly J. Gospel According to the Klan the KKK’s Appeal to Protestant America, 1915-1930. University Press of Kansas, 2017.
Dixon, Jr., Thomas F. The Clansman, an Historical Romance of the Ku Klux Klan. University of North Carolina at Chapel Hill, 1997.
Gordon, Linda. The Second Coming of the KKK: The Ku Klux
MacLean, Nancy. Behind the Mask of Chivalry: The Making of the Second KKK. OUP, 1994.
Parsons, Elaine Frantz. Ku-Klux: The Birth of the Klan during Reconstruction. The University of North Carolina Press, 2015.