The HSL separation techniques use hue, saturation and lightness values to mask areas in the design. The HSL window is located in the Window Menu. It should be opened before you attempt to use any of the listed methods.

HSL separator brush

This feature is particularly useful for masking out specific areas.

1. Open a tonal design and go to Window Menu > HSL. A small window will open.
   
2. Add a layer to your design which will become the mask layer, and activate it in the Layers Palette.
3. Using the Pipette Tool, click on the colour you want to create a mask for. This colour will appear in the colour box in the HSL Window.
   
   When this window is open, all brush and pipette actions are overridden. The Pipette Tool picks colours directly into the colour chip in the HSL Window, rather than into the normal foreground colour box in the Tools Palette.
   The HSL numbers automatically default to 10. These numbers control the amount of colour and tone that are included when painting to separate on a layer and can all be adjusted manually.
   
   
4. Begin to paint on the 1 bit layer and you will see that it will only allow you to paint within the set parameters, according to the colour in the HSL Window.
   
5. Experiment by changing the HSL values. Press ⮐ (return key) on the keyboard after changing any of the numbers to confirm the change. The higher the values, the more colours will be included, the lower the numbers, the smaller the range of colour and tone which are masked as you paint over the design.
   
   You are only able to paint on colours that fall within the selected percentage tolerance of the chosen colour that is being painted. For example, if you select a blue colour, when you paint over yellow colours, no paint will be transferred.
   
   
6. Finally, if you are working on a large design, just use the separator brush on a small area and choose Separate Menu > HSL to create the mask over the whole design.

Delta HSL: Set the values in the HSL Window

This variation of HSL makes it easier to accurately set the values in the HSL Window. You often have to experiment with values until you find the right numbers to use for the separation, so delta HSL is designed to find the right values for you. It works by identifying the different colours you want to include in your mask.

The HSL Window has a button on it, labelled ‘0’. If you click on it, the values are set to zero. This is the starting point for creating your delta HSL range.

1. Go to Window Menu > HSL.
2. Select a colour with the Pipette Tool to set it as the starting colour in the HSL Window.
3. Click on the ‘0’ button to set the HSL values to zero.
   
4. Hold down ⇧ (shift key) and click with the Pipette Tool on another colour. This adjusts the values to display the difference between the original colour and the one you have just clicked on. Similar colours will produce small numbers and very different colours will result in high numbers.
   
5. Test the effectiveness of the new values by painting over the area with the Brush Tool on the mask layer.

6. If the desired area is still not being included, repeat Steps 4 and 5 until the values are high enough to include it all.
   

This method stores the maximum values in the HSL fields. Therefore, the numbers never go down. This is so you can select multiple colours if required, but only record one value which will include them all.