
Here's the base illustration of a mermaid and her friend Mr Fishy that I created in Photoshop. Miss Mermaid needs some scales on her tail but I'm too lazy to paint them in by hand, so what can I do to make life easier? Make a brush of course!
For convenience I have the tail painted on a separate layer so we can easily make a clipping mask of the scales over it.
1. How to Create a Brush
Step 1
Create a New Document by going to File > New or Control-N on the keyboard. As the illustration is in CMYK we will have to make the brush in CMYK, so make sure your Color Mode matches the document you will be using it in.
Step 2
Create a New Layer by pressing Control-Shift-N.
Create a circle with the Ellipse Tool (U) and stroke the outside with black. Copy and Paste to create three circles aligned horizontally. Copy and Paste the circle again, and offset these two circles between the top three.
Next move the layer with the two circles below the top row of circles in the Layers panel. Repeat this process until you have four rows that go 3-2-3-2 and resemble basic scales. It can be useful to set up guides to make aligning the circles easier. Press Control-R to bring up Rulers and drag out Guides from the Rulers by using the Move Tool (V).
Step 3
Paint in a circle over the first scale using a hard brush and a medium grey. To quickly select the BrushTool, press B on the keyboard.
Step 4
Lock the pixels by pressing the small chess board next to the word Lock on the Layers panel. The reason we do this is so that we only effect the pixels we have already painted. Next, using a soft brush, paint in a darker grey at the top and add in some light dots for detail.

Step 5
Copy this painted scale by having the Move Tool selected (V) and holding down Alt. Then drag the circle across the document and release. This will create another instance of the circle on its own layer in the Photoshop document.
Arrange the layers so that they overlap. If you are unsure which layer you are on, either hold Alt and click on a circle and it will select the layer you are on, or hold Alt and click on a thumbnail in the Layers panel to show the marching ants on whatever is on that layer.

Step 6
On a few of the scales, play with the Levels to add some variety. You can quickly bring up the layers dialogue by pressing Control-L.

As you can see on the image below, I have made the darks punchier. This breaks up the repetitiveness of the brush, which makes it more natural. Carry on this process over a few random scales.

Step 7
Select all the layers with scales by holding Shift and clicking the desired layers. Merge the layers by pressing Control-E. Then bring up the Levels dialogue box by pressing Control-L, and slide the white triangle to over-expose the whole image. Turn off the layer with the circle outlines.

Step 8
Taking the Eraser Tool (E) and using a soft brush, soften edges so that when the scale brush is used there won't be crisp, curved edges on the periphery of the design.

Step 9
Save the base brush shape by going to Edit > Define Brush Preset and give it a memorable name.
2. How to Use the Brush
Step 1
Test out the brush as is, with no brush dynamics set up. Notice how we can create a seamless design by using the scale brush as a stamp.
Step 2
In this example I have duplicated the layer with the scales, pressed Control-T to Transform, and selected the Warp icon in the toolbar, which looks like a curved window. As you can see, we can warp the form to fit curved shapes—perfect for the mermaid's tail!

3. Applying Simple Scales to the Tail
Step 1
Rotate the document 90 degrees Counter Clockwise by going to Image > Image Rotation > 90° CCW. I have done this so that the scales flow in the right direction. The rounded edges should point towards the tail tip.
Step 2
Select a purple that is darker than the darkest part of the tail.
Step 3
Stamp scales all over the tail, varying the size. This can be done by pressing the square brackets in your keyboard, [ or ].
Step 4
Press Control-T to bring up the Transform controls.
Step 5
In the toolbar there is an icon that looks like a curved window; this is the Warp Tool. The Warp Tool can also be accessed by going to Edit > Transform > Warp. With Transform active, press this. This will release handles in your Transform controls. You can use this to move the artwork around more fluidly. This can be done by pulling or pushing the handles or by moving the horizontal and vertical lines inside the selection.
Move the scales until they look as if they follow the form. This may take a little getting used to, and if you wish to start again then press the Escape key.
Here's the simple scale version where I have painted in some highlights with some very pale purple. We can take it a step further if you'd like some colour variation across the tail.
4. Applying Multi-Coloured Scales to the Tail
For this we will be moving on from the simple scales to a coloured version, and it couldn't be easier!
Step 1
Create a New Layer by pressing Control-Shift-N and paint in colours from the illustration palette with a soft brush so that they blend together.
Step 2
Move the colour layer below the modified scales from earlier.
Step 3
Select the scales by holding Control and clicking on the scales thumbnail in the Layers panel.
Step 4
While on the coloured layer and with the scales selected, press the Add Layer Mask button at the bottom of the Layers panel. This looks like a rectangle with a circle.
Step 5
Unlink the colours layer and the mask by clicking on the chain "link" between them. This is so that when we move the colours layer, the mask will not move. Transform the colour layer by pressing Control-T so that the colours lie along the tail in a pleasing fashion.
Step 6
Once we are happy with the colour placement, set the colour layer to clipping mask by right clicking on the layer and selecting Create Clipping Mask. Next play with the Layer Blending Modes. Here I found that Color Dodge was the most pleasing. Your results may vary.

Here is the lovely Miss Mermaid and her gorgeous scaled tail!
That is all you need to create a quick and easy mermaid tail! This is a great way to work. If you or your client decide the tail should be a different colour, it's a simple fix to change one layer rather than repainting the entire tail.
Conclusion
In this lesson you'll have learned how to create a simple scale brush and how to convincingly apply it to any aquatic creature, reptile, dinosaur or dragon. I hope you enjoyed this quick tip.
Feel free to check out the Mermaid Scale Brush I have uploaded with this tutorial. See you again soon!