Painting Translucent liquids (Patreon)

So! One of the tutorials requested in the last $10+ Patron request post was how to paint translucent liquids, such as for potions. I think the best approach on this is moreso "teach a man to fish" rather than to just say "here is the exact and only way to do it." 

All original reference comes back to real life. If you're not sure how to paint something, find something that demonstrates what you're trying to replicate.

 So let's talk about juice. 

What makes juice/tea/liquor/coffee such a good potion reference is that it is that there is an infinite range of color, opacity, amount of pulp, bubbles, etc. You just have to find the right reference! From there, you're just interpreting the common denominators: how shiny is the glass? How opaque is the liquid? Where is the light source and is it tinted? How thick is the glass? And so forth.

(All images above are CC0 Creative Commons to the best of my knowledge since I am using these on a paid post. You can find links to royalty-free photos in this article or find simpler images just with Google.)

For more traditional fantasy container shapes, Google search "larp potions," "boiling flask" (which has the traditional round potion shape), or "ren faire potions." This can help with painting the highlights on the glass.

I primarily want to explain painting the liquid itself, which is a step often overlooked. For each image below, the light source is a soft white light coming from the upper left.

The first thing to keep in mind is opacity. If the liquid is very opaque, painting the form will be light painting a sphere with the top sliced off. This is pretty easy once you've practiced painting basic forms. The more transparent the liquid is, the more the light can bounce around within it, and the more that the background color is visible through it. 

And the version without captions:

If the background was blue, instead of the highlights being very pure white, they would be blue more like this to reflect the light around it:

But we'll stick to the white background for demonstration's sake.

I want to show the difference between painting with and without ambient light. Ambient light is light that bounces around in a space- jumping off of walls and particles/atoms in the air. It curves around forms, which creates a great sense of depth as you can see in the image below. I add ambient light around the rim of almost all my paintings. This was painted with one brushstroke around the outer edge with the default soft round brush:

The next step to painting believable liquids is to add imperfections, bubbles, and reflections. Adding these one at a time really takes this to the next level.

Methods:

• Bubbles, which I gently lay down with a textured spotted brush and a very bright, saturated color. Bubbles should vary in size and softness. I then erase away at them with the default soft round brush to make them more subtle at the edges.
• Edge highlight. Where the liquid surface touches the container, there is a bright, uneven, vivid highlight that circles the glass. This can be painted with the hard round brush with opacity AND size adjusting to pressure.
• Small surface bubbles form around that edge highlight (default hard round brush) and vary in size/density depending on how frothy you want the liquid to be
• Dark and light hard-edged reflections on top of all of the other layers are truly what make the liquid feel like it's in a glass or other shiny container
• Then I boosted the contrast at the end and did a tiny bit of polish

Ta-da!!

These steps can be applied to any variety of colors once you know how to break them down into a consistent workflow :) I hope it helps!