Officially, it is a bodypaint. It is nothing like the textile latex, which you often see on the more 'kinky' pictures. Technically, liquid latex is just that: liquid latex (rubber) that has not been hardened yet ("vulcanised").
Technically, it is latex with colors and a small amount of sulfur and ammonia to keep it liquid in the bottle. When applied to the skin those ingredients will vaporize and its effect is that the latex will dry up into a sturdy but flexible material that remains sticking on the skin.
And yes, the liquid stuff smells bad (but you will get used to that in no-time).
Dried up latex is experienced as a comfortable wear: it is a perfect fit on the body and blocks loss of warmth.
The body will not be fully covered with liquid latex and we will be working in a steady environment with proper ventilation (which is also required for the vaporized sulfur and ammonia).
Liquid latex is applied with a foam brush (well, multiple of them actually). Applying liquid latex has to be done in layers: the first layers draws out the main contour lines. One single layer of liquid latex results is transparent, so multiple layers are required in order to get the proper color visual. So, we start with applying the first layer of liquid latex. The shapes will be drawn roughly. Then we have to let the first layer dry, which takes about 20 minutes on average. Then a second layer will be applied: now the shapes will be filled thicker and lines will be redrawn. Again, this layer has to be dried then, too.
This process of adding new layers will be repeated until the desired color and layer thickness has been reached. When the last filling layer has dried up, the detailed lines and shapes will be drawn on the body. When they have dried up and are considered to be good enough, you will be covered in a special designed liquid latex outfit.
Applying the latex is a very time consuming process. It can easily take 5 to 8 hours for a single session, due to all the layers and drying moments in between. So when you wish to participate in a Liquid Latex session, make sure you have reserved the whole day for it!
When you are allergic to latex, ammonia or sulfur then you probably should not be participating in the Liquid Latex project. So far I have never met a person who has such allergies, but if you are one of them then please reconsider participation in this project (I have other themes to offer)!
Unlike the long duration of appliance, its removal is done within a few minutes. It's very easy to peel off the liquid latex. Do mind though, that if you have a lot of body hair it can be somewhat unpleasant to remove the latex. It is like a wax: the hairs get stuck in the dried latex and when you peel off the latex, you are also pulling all those hairs along with it.
Some models don't feel a thing, but I've also seen models who turned into cursing demonic creatures when the latex got removed.
For avoiding calling in some exorcist, I use a body oil that is applied before the liquid latex is put on. It soothens removing the latex and it makes your skin 'glow' warmly (it also makes you look a bit taller).