Ethereal Curtain

Ethereal curtains, also called curtains of vaporous color, were the barriers between the Deep Ethereal and the various Border Ethereal regions of the Ethereal Plane. Some scholars instead reported a single infinite curtain that separated the two regions of the Ethereal, in which case it was called the Wall of Color.  

Description

 
See!? It does look like a wall of chocolate! Xanxos likes chocolate, especially when it's dribbled over raw Elf. Are you an Elf? Hey, come back here!  
— Xanxos the slaad, showing off the ethereal curtain to the Plane of Ooze before lunch.
    Ethereal curtains appeared like enormous sheets of colored vapor, which continuously were in motion. The motion had been described as the flapping of a world-sized flag. Motes of sparkling Light flickered over their surfaces. Some who had seen ethereal curtains described them as looking something like the northern lights found on some worlds.   The curtain or curtains were only visible from the Deep Ethereal side and never from the Border Ethereal.   Anyone separated by a curtain from the Border Ethereal was completely protected from any Harm by any force or being on the other side, whether on the Border Ethereal or the bordered plane.  
Curtain Colors
The color of an ethereal curtain indicated to which Border Ethereal region it led. To those who believed in a single ethereal curtain, the curtain had separate colors in different areas, which indicated the destination. Trusting in the color of the curtain to Lead you to your desired target, however, was considered risky.   The colors of the curtains to most of the major planes are listed in the table below, along with other methods of planar travel:  
Plane Planar Fork Material Pitch or Chord Color Pool Ethereal Curtain
The Prime Steel C Silver Metallic Silver or Turquoise
The Feywild Emerald green Opalescent white
The Shadowfell Spiraling black Silver or dusky gray
Elemental Planes
Elemental Plane of Fire Copper A Fire Emerald Flickering green or red
Elemental Plane of Earth Zinc A Moss granite Flickering gray or brown
Elemental Plane of Water Lead A Dark blue Flickering blue or green
Elemental Plane of Air Tin A Pale blue Flickering white or blue
Para-Elemental Planes
Smoke Bronze A Pearl
Magma Brass A Maroon
Ooze Zinc/Lead A Chocolate
Ice Pewter A Aquamarine
Quasi-Elemental Planes
Radiance Copper A♯ Shifting rainbow
Mineral Zinc A♯ Milky pink
Steam Lead A♯ Ivory
Lightning Tin A♯ Violet
Ash Copper A♭ Dark gray
Dust Zinc A♭ Dun
Salt Lead A♭ Tan
Vacuum Tin A♭ Ebony
Energy Planes
Positive Energy Plane None known None known Shining white Shining white
Negative Energy Plane None known None known Cold ebony Glossy black
Transitive Planes
Ethereal Plane Glass B Spiraling white
Astral Plane Quartz B Swirling gray
Outer Planes
Outlands Platinum C Leather brown Brown
Cynosure
The Fugue
Mechanus Silver C Diamond White
Arcadia Gold Pale yellow
* Abellio Gold C♯ Saffron Pale yellow
* Buxenus Gold C♯ major Pale yellow
* Layer 3 Gold C♯ minor Pale yellow
Celestia Gold Brilliant yellow
* Lunia Gold D Gold Brilliant yellow
* Mercuria Gold D major Brilliant yellow
* Venya Gold D minor Brilliant yellow
* Other layers Gold Unknown Brilliant yellow
Bytopia Gold Dark yellow
* Dothion Gold E♭ Amber Dark yellow
* Shurrock Gold E♭ major Dark yellow
Elysium Gold Dark green
* Amoria Gold E Opal Dark green
* Eronia Gold E major Dark green
* Belierin Gold E minor Dark green
* Thalasia Gold Dark green
The Beastlands Gold Emerald green
* Krigala Gold F Emerald Emerald green
* Brux Gold F major Emerald green
* Karasuthra Gold F minor Emerald green
Arborea Gold Bright blue
* Arvandor Gold F♯ Sapphire / Dark Green Bright blue
* Aquallor Gold F♯ major Bright blue
* Mithardir Gold F♯ minor Bright blue
Ysgard Gold G Indigo Purple
* Muspelheim Gold G major Purple
* Nidavellir Gold G minor Purple
Limbo Nickel C Jet Swirling black
Pandemonium Iron Crimson
* Pandesmos Iron C♯ Magenta Crimson
* Cocytus Iron C♯ major Crimson
* Phlegethon Iron C♯ minor Crimson
* Agathion Iron Unknown Crimson
The Abyss Iron Swirling red
* Layer 1 Iron D Amethyst Swirling red
* Other layers Iron Unknown Swirling red
Carceri Iron Gray-green
* Orthrys Iron E♭ Olive or red Gray-green
* Cathrys Iron E♭ major Gray-green
* Minethys Iron E♭ minor Gray-green
* Other layers Iron Unknown Gray-green
Hades Iron Dark red
* Oinos Iron E Rust Dark red
* Niflheim Iron E major Dark red
* Pluton Iron E minor Iron gray Dark red
Gehenna Iron Bright red
* Khalas Iron F Russet Bright red
* Chamada Iron F major Bright red
* Mungoth Iron F minor Bright red
* Krangath Iron Unknown Bright red
The Nine Hells Iron Red & black
* Avernus Iron F♯ Ruby Red & black
* Dis Iron F♯ major Red & black
* Minauros Iron F♯ minor Red & black
* Other layers Iron Unknown Red & black
Acheron Iron Metallic red
* Avalas Iron G Flame Metallic red
* Thuldanin Iron G major Metallic red
* Tintibulus Iron G minor Metallic red
* Ocanthus Iron Unknown Metallic red
    ↑ Glass always breaks in casting of spell. ↑ Quartz breaks about half the time in casting of spell. ↑ Precise determination of destination layer not possible. ↑ Lower layers may be reached through random chords.  

Travel

If a traveler faced an ethereal curtain, desire alone was all that was necessary to enter through the curtain and find oneself on the other side, at the border of another plane able to see into it from the Ethereal. (Strangely, something prevented anyone from reaching the Border Ethereal of the Material Plane around Krynnspace; the ethereal curtain to this part of the multiverse was somehow blocked.)  

A diagram depicting ethereal curtains at the barriers between the Deep Etheral and the Border Ethereal regions of an Inner Plane and the Prime.
  Likewise, any planar traveler desiring to leave the Border Ethereal of any plane needed only to will it, and she or he would immediately appear facing an ethereal curtain of the appropriate color. To an observer still remaining on the Border Ethereal, the traveler would appear to vanish in an enveloping, roiling mist. (An exception to this was found on the Border Ethereal of the Demiplane of Dread, from which it was impossible to enter the Deep Ethereal.) Later scholars believed that the only way to enter the Deep Ethereal from the Border Ethereal was with a Plane Shift or Gate spell.   Traveling along a curtain before entering it would allow one to appear at a point overlapping a different location on the bordered plane, but since it was not possible to see through the curtain, it was generally not possible to predict which direction of travel along the curtain would Lead to which location, nor did distances traveled in the Deep Ethereal in any way correspond to distances in the Border Ethereal. Some travelers of The Planes argued that those who were clever enough could recognize patterns in the flashing lights in the curtain to find previous sites of entry.   Traveling to another curtain or area of a curtain could feel like a journey of anywhere from 10 to 1,000 hours, though the time that had actually passed in the Material Plane would not be as long. Traveling to the place where passage through a curtain would take one exactly to the desired destination in the Border Ethereal always took longer than if someone simply had willed to reach a given border in general.   If a visitor to the Deep Ethereal was under the effects of a magic item or spell, such as Etherealness, and the duration of the magic wore off, the traveler would immediately be forced through the nearest ethereal curtain and would materialize on the corresponding plane of existence.
Alternative Name(s)
curtains of vaporous color
Location under