Below is how I apply my semi-permanent hair color on my sisterlocks. I didn't have a bonnet hair dryer so I apply this color during a sunny day in Florida, and I sat under the sunlight for about 15min. Before I continue further, please note that most semi-permanent hair coloring is DEPOSIT ONLY, especially if you get the semi-permanent hair color that has no PEROXIDE (Lightening agent), and no AMMONIA (open the hair shaft). Look at a semi-permanent as a way to enrich the color you currently have, and not as a color dye. So to make sure we are on the same page, don't expect this dye to change your black/dark brown hair to a rich red or blond. I highly recommend doing this color refresh a couple days before your schedule retighten, this is due to the possibility of unraveling locks.

Material Needed
Cheap Shower Cap
Semi-Permanent Hair Color  
Towels
Gloves
Old Shirt

Steps 1 - Make sure your locks are clean. You may need to do a clarify wash since this semi hair color requires clean hair to work effectively. Note: Please read the instructions of your semi-permanent product if yours is something other than Adore.
Step 2 - Separate your locks into four sections and proceed to tie them down with a rubber band of your choice.
Step 3 - Use a protective cream around the hair line. A protective cream can be petroleum jelly for example. Note: Petroleum jelly prevent hair coloring form showing up on your skin after you rinse out your color.
Step 4- Apply the color to each section, try to avoid the scalp as much as possible. Note: I focus mostly from the tips and on (new growth area was just extra). The new growths didn't really need as much coloring since my new growth is naturally black.  Cover with a plastic cap and sit under a heat generated source for up to 15 min.
Step 5 - Rinse, Shampoo, and Condition (if needed). Optional but highly recommend is to use another glove to rinse out your hair. The reason I noted this as a optional is if you plan on going out that day, the color rinse will appear on your nails, if you don't plan on going out, then you can disregard the second set of gloves. Note: I highly recommend using a moisturizing shampoo and conditioner, and not a clarify shampoo. You want to retain as much of the color deposit as you can, as well retain moisture.

You can find the final result of my coloring here. The hair coloring I used was Adore Jet Black 121 and you can check out my review here. Final Note: If you are unsure about anything at all, PLEASE seek a professional in applying any sort of hair coloring to your locks. Coloring is only for settle lock ONLY!