Slime Time

  • Software:Photoshop CS6  ·
  • Difficulty:Beginner

Rules of the Exercise

  • 1
    Download and open the practice worksheet for this exercise.
  • 2
    Observe and analyze the subject matter. Follow the guides of the instructor's notes.
  • 3
    Submit your work for this exercise under the "Submissions" tab for grading!


  Sometimes creature designs call for things to get a bit slimy, gooey and downright messy. With this exercise our goal is to understand how we can paint slime!There are several different ways to render out slime so feel free to take your own references. Go out and create slime from borax and Elmer's glue! Crack open a few eggs! Or just take a bit of shower body wash gel and snap a picture or two! If you can get your hands on a physical resource and play around with it, the better you’ll understand that slime can come in all shapes, densities, colors, and sizes.Caution: Mess may be created during the process of creating slime. Majority of “slime” is often not hard, but instead “melty” and gravity usually creates its new form. Study how gravity can affect slime on a surface, for instance if it's hanging off something. The great thing about studying slime is that it’s between a solid and a liquid. Along with it being translucent, it can appear to be a challenging material to understand.  Caution: Mess may be created during the process of creating slime. Majority of “slime” is often not hard, but instead “melty” and gravity usually creates its new form. Study how gravity can affect slime on a surface, for instance, if it's hanging off something. The great thing about studying slime is that it’s between a solid and a liquid. Along with it being translucent, it can appear to be a challenging material to understand. Below is the practice worksheet that you can download. You can find this on the “Downloads” tab under the header image near the top of this exercise.Exercise_44_SlimeTime


  • Create your own References!
  • Remember that the center of slime is usually more dense and opaque than thin strips and the outer ridges, as represented by the soft green color on the practice sheet.
  • Since slime is often times reflective, be aware of the reflection of light in the room and keep it consistent. 
  • Don’t be afraid to use multiple / screen / overlay layers when working with slime, it will come in handy when working with objects that are underneath the slime as well!

Below are some of the reference pictures I took after making green and blue slime! I made it from watching this video and used clear Elmer’s glue instead of white glue!Exercise_44_SlimeRef


  This exercise was extremely useful for understanding light through translucent objects, along with how some materials may wrap or hang around an object. The difficulties I ran into were understanding that it's often times not just one bright white highlight on an object to make it look like goo. Instead it's the accent lights and the soft highlights that help sell a good goop; that and bubbles... Lots and lots of bubbles. Eventually, I started thinking about how these forms aren't just two dimensional paintings, but instead in reality they have mass to them, and you can clearly see it by what's laying inside of them. When working with goo or slime, it's always important to remember that the center of the mass is more dense and thicker in opacity along with darker. When gravity takes effect of drips of goo that hangs, it shows that thinning of slime can cause it to pick up the color of the object it sits in-front or lays on-top of. Color/density of ooze will also factor into how clear you can see underneath the object such as the dark green, compared to the light blue. Creating a Goo Monster Now while I used my self-made reference pictures for understanding the slime, I came to our friend Otis, the Ooze, who is the third object on our worksheet. I didn't want him to read exactly like a realistic goo monster, but instead be a bit fantastical along with being extremely adorable. Another thing I would like to point out is the other objects that aren't really the focus of this study, such as the fingers and hands. While I could spend more time rendering them, their usage wasn't so much about rendering them out to be perfect, but instead to understand what's going on under the surface of the slime. Step-by-Step Guide Below is a step-by-step guide on how I went about this process as well as studying. While most goo isn't represented on these extremes, say in animation, it was important for me to try and get as real as possible all while not making an exact copy of the reference. I hope that this guide can help show you guys how to render and think about goo, whether it be hyper-realistic or for something cel-shaded.

  1. Line Art - The line art layer is pretty straight forward, what I can recommend is keeping it simple, don't over detail all the little highlights. As you can see with the skull example, it just got out of hand and eventually the layer got taken away. It's great for building upon, but don't get lost with all the highlights going on.
  2. Base Color - The base color will depend on if you enjoy working from dark to light or the reverse. I try and find something darker and not overly saturated. When working with the hands and other objects, don't worry too much about doing fancy over-lay layers just yet, keep it simple and just color over to help you get started.
  3. Block Out Colors and Initial Detail Pass - This is the time to have fun and just throw colors around. I'm keeping in mind basic ideas of light sources and with goo, this is transparent when it thins out. With the skull, I've color-picked from the skull and painted it on top of the blue slime area. Block things out in this phase, and if you need to set highlight place holders to help guide the direction of light, go for it!
  4. Refine Pass and Soft Light - Thinking about goo as a form helps here; there is a center mass and its density will not be completely covered up, but soft highlights help show that there is mass. I clean up edges at this point and start to take into account the time spent on painting these. It hit me at this point to be meditative and just feel it out as opposed to driving myself crazy and trying to match things one for one. Keep in mind the ideas of the subject matter with what's going on and play with them at your own leisure.
  5. Remove Outline and Add Bubbles! - This phase was my favorite. The lines are removed and the shape and form is starting to come together nicely. I'm pushing highlights subtly still, and focusing on big bubbles! The bubbles were becoming a pain, not only physically taxing on my hands, but mentally driving me crazy. I created a few brushes for myself, based on studying the reference pictures I took. I noticed a pattern in the bubbles and that those bubbles in fact created their own shadows and highlights inside the mass. The bubbles sit like air-pockets inside the goo and move in a direction that the slime is going.
  6. Final Detail and Strong Highlights - The Pièce de résistance comes with adding the final stronger highlights through the goo! While the previous version shows some highlights, this is oftentimes the last strong light. Goo/slime seems to have a film-like surface that's wet and highly reflective and you can achieve this look by adding a new layer and changing it to screen layer mode. I also like to erase away at the edges of the strong highlight slightly to not make it a strictly white blaring highlight. Tiny bubbles also get their own little shadows and stronger highlights, and adding a shadow base with a hint of the object's color in the shadow helps sell its translucency .

Exercise-44-Step-by-Step-Process This exercise took a lot of time and patience for myself, but I sure did learn a lot. Slime can be one of the more difficult materials to render and understand, but don't give up, take it slow and be patient because in the end it will pay off. When you finish the exercise, remember to submit the result to the “Submissions” tab near the top of this exercise. You can see other submissions alongside your own.