I'm not telling you to do this, but this is what I do. I'm a #4 but the last hair I received was a 1B/2. I simply dipped it in straight peroxide, laid it on the windowsill in the sun, let it dry and repeated the process 2-3 times until it was the right color.
I have Wags NC, "virgin", so it hasn't been processed already, just steam processed for curls.
Again, this works for ME. If you try this method, please strand test 1st.
I was afraid that hair dye would loosen my curls. Plus, I'm lazy and cheap and couldn't imagine dyeing bundles of hair. It's a pain in the arse to have to dye my own edges every month to cover this gray. lol