I have been a member of

for some time now, and as such, I am called upon daily to help decide what enters the group, and what does not.
It has been made clear by the submissions, that many folks just plain don't understand what Golden Age illustration actually IS. It is not just any illustration, any drawing or any piece of concept art. Rather, it is a defined style set, and there are certain parameters that one can judge how well it fits the title "golden age."
First, a brief history: The Golden Age of illustration occurred in the late 1800's through the early to mid 1900's, and was primarily an art phenomenon found in children's books. It's influences stem heavily from the arts and crafts movement, as well as the Pre-Raphaelite and art nouveau movements, with a heavy dash of eastern and oriental influence. These works were almost always done in conjunction with a story, hence, "illustration," and despite their rather adult themes (often containing violence, and nudity to the point where it could have been considered nearly pornographic) these artists most often had their work popularized in children's tales.
The first example I'll use is my personal favorite artist, Arthur Rackham. In addition to his work for children's stories (most notably Peter Pan, the Wind in the Willows and Alice in Wonderland) he also did some personal artwork and portraits, magazine work early on in his career, and many illustrations done for more adult works, such as his suite for Wagner's opera, Ring of the Nibelung.
Rackham's work became popular for it's beautiful, intricate line work, it's subtle sense of the lurking darkness, and for the expressiveness of the figures. Not to mention, the muted color palate he stuck to was perfectly suited to the limited color capabilities of the printing presses of the time, and as such they could be more easily reproduced. His work can be seen here:
[link]For a more Art Nouveau approach to illustration, we come to Aubrey Beardsley. Beardsley was more of an ADULT artist than anything else, and much of his work is highly erotic and downright pornographic, even by today's standards. (Note: Do not Google Aubrey Beardsley at work or school.) His work was mostly devoid of color, and revolved around flowing, expressive linework, mostly in human and floral forms with limited animal forms, in keeping with the style (art nouveau typically doesn't include animals.) Some of his linework can be seen here:
[link][link]Another such artist, considered to be one of the 'greats' of the movement, is Edmund Dulac. Much like Rackham, he relies on beautiful expressive lines and figures, but unlike Rackham, he tends to use more color and lighting to set the tone of his pictures, and as such they tend to be much brighter and lack some of the "creepy" element Rackham tends to have. The two are often compared and it can be hard for their fans to play favorites.
[link][link]Lastly, we come to Warwick Gobles, who is best known for work on the tales of the Arabian Nights. His work displays much of the same dedication to linework as the rest, with a bright color scheme, and the art nouveau love of plant and floral forms. Unusual for Art nouveau, however, his work also displays a lot of animal forms, other than the occasional fish.
[link][link]That being said, how do we decide what is "Golden Illustration," and what is not? How does one decide how to sort the artwork submitted to the group? Well, let us look at some of the themes present:
Linework: Golden Age illustrators nearly always pay close attention to the linework. Color and painting and lighting are often secondary aspects that the drawing doesn't really "need," but that make the drawing more interesting.
Color: Even the brightest of colors have something of a dull edge to them. Even though this may be the result of the equipment of the time not being able to recreate vibrant colors, or that they would be too expensive to print; the relatively muted color palates definitely play a big part in the style. It would be very difficult to include a vibrant, digital neon green in a picture and still have it look the part of "golden age."
Content: This is more important than some people realize. While it is perfectly POSSIBLE to fit the style criteria with ANY subject matter, content plays a large role in the style. There were a few pictures here and there of personal work by the aforementioned artists, but mainly, the work that made the style popular was illustrative. Illustrative work means that there is a STORY behind it. Remember the portrait Rackham did of his daughter? No, you probably don't, because those portraits were never very popular. But remember the image of Ondine in the river? or the more iconic scenes of Alice in her wonderland? Those images became more famous because of the story associated with them. This is illustrative art, and on some level, it should be actually be ILLUSTRATING something. Mythical beings and creatures, such as Djinns, goblins and of course fairies played a huge role in the artwork of the time.
Media: It is perfectly possible to create something in the style of "Golden Illustration" digitally. It has been done before and done beautifully by artists on DA such as

. However, they obviously did not have photoshop in the late 1800's, and as such the effect is often best realized by using traditional means. Pen and ink, watercolor, and oils were usually used for the original artwork, and then there were color prints made into plates. Golden Age artwork, even if it is made digitally, should at least emulate the traditional media used to make them.
Style: "Style" can be hard to define, but what I mean is that it in general tends towards semi-realism, with the figures tending to have believable anatomy based on real forms, and are for the most part not surreal. Special attention is usually given to plant forms, and human figures tend to be mostly realistic, with goblins and fairies tending more towards caricature.
Now, don't get me wrong, one can create something that fits the 'label' without meeting each of these criteria. It's possible to fit the criteria without tedious linework, or without muted colors, or without using watercolors; however, these are the criteria most easily associated with the style.
I am by no means an expert on this topic. I'm merely a fan of the artists listed, like their work, and joined the group to find work by modern artists who also like the style. I'd never go pester someone and tell them that they're "doing it wrong" because they're missing one of my narrow little bullet points up there. However, these are the things I usually look for when approving artwork to the group.
Hopefully, this clears up a little of the confusion surrounding the

group, and now you know that it is not just a posting ground for any old photorealistic pencil sketch of your grandmother, or any piece of illustration in general, but a defined set with definite criteria that should be met to qualify for a spot in the group.
I hope this little tirade was informative, and I hope I don't sound terribly ignorant or pretentious with my saying so. Again, I am hardly an expert, and if you have anything to add, or to correct, do not hesitate to let me know.