https://sims4studio.com/thread/386/add-swatch-existing-hair-beginners?page=1

Introduction

This tutorial will show you how to add a new swatch to a hair.package. It can be used to add a new one to a hair you have created or one that someone else created. Please note that if you use this tutorial to add a swatch to someone else's hair it will not create a whole new .package. Instead it will simply add a swatch to the existing one. This means that it will overwrite the original when you place it in your mods folder. For this reason it is recommended that you do this for your own personal use only and, if you must share a .package like this, that you gain permission from the original creator before you share it.

What you will need

Sims 4 Studio

A 2D editor capable of managing .dds images. Photoshop, GIMP, and Paint.net are popular choices. Photoshop and GIMP both require a plugin in order to work correctly with .dds images.

Instructions

  1. Open Sims 4 Studio and enter your creator name if you have not already done so.

  1. A navigation box will appear. Browse to where you have saved the hair you wish to add a swatch to and select it.

  1. Click the Add Swatch button.

  1. You will see a white square appear at the end of the other colored squares in the Swatch thumbnails box.

  1. Open the image you just saved in your 2D editor. It will look something like the image below. Note that the hair texture only occupies a small part of the large image.

It is located in the upper left corner. When you recolor a hair you must be sure that your new hair texture is located in the exact same place.

  1. Paste the texture you want to use as a new layer. I am using a texture I found at Jennisims Hair - Textures for this tutorial. You can see that this square is larger than the area covered