Coloring a glass of water

After the last few posts you should all be experts at refilling. Sorry about how long that took, but when I cover a how to, I like to make sure you know as much as possible so you don't make mistakes. Today I want to talk about coloring a glass of water. Back in June I discussed coloring transparent things, and this falls right in line with that post. Later I want to talk about shadows on clear things, so I figured I'd better do a quick tutorial on water and other clear things before I really confuse you (water will also be something I discuss a lot in the future).

Coloring a glass of water
To break it down, a simple glass of water has 3 levels: The glass, the water, and the straw (or ice cubes, or fly that drowned, or whatever else is in the water). I like to color from the outside layer and work my way in- that way it's easier to see how much or how little color you need on the last layers.

Layer 1 - The Glass
My glass is going to be clear, but with a tint of purple. So first I start out by coloring only the edges of the glass with a light purple (it looks more pink on my screen). Notice that I am not using too thin a line, since I need enough color there to blend. Then, I fade the purple out to the edges with a colorless blender. I fade by starting on the inside and pushing my color out almost to the edge. Now my glass looks purple but clear. In hindsight, I probably should have used purple on the back-bottom round edge of the glass as well.

Layer 2 - The Water
My water in real life is clear, but that's boring and doesn't make people think of water. We're going to exaggerate the water, and since most people think that water is blue, we'll use a light blue to do exactly the same steps as we did with the glass. Color the edges, then feather it to clear in the middle. Notice though, where the water meets the edge of the glass I don't go all the way to the black line- I leave a tiny rim of the pure purple. This keeps the glass tinted purple and shows the thickness of the glass.

Layer 3 - the Straw
I wanted to show a bright red straw, but each time the straw passes through a layer it will get lighter since it has that much more "stuff" between it and the light. So my straw will be most vibrant outside the glass at the top, half vibrant where it passes through the cup, and less vibrant still where it enters the water. Again, notice where the straw meets a colored layer-edge I leave a tiny rim of the layer color visible. I also drew in a little line to show you better where the straw enters the surface of the water (really the straw would be visually bent and distorted from the angle of the light reflecting off the surface of the water, but we're not getting into that).

For my final colored piece I blended the straw there at the edges of each layer so it was a softer transition. Then I added a simple shadow made from the two main colors of clear- the purple and the blue faded out. If I really wanted to get detailed then my next step would be to add glints of light and reflections with tiny dabs of Opaque white (more on light and shadows later).