Colour B4, does it work on dreadlocks?

Hey!

So I bought some Colour B4 to use on my hair. I'm naturally blonde but I currently have dark brown hair, that I've had for a couple years or so, though I haven't dyed it for about a year now and my roots are very long. I've previously dyed my hair bright red using XXL, for several years prior, if that's helpful at all. My issue is, I have dreadlocks.

For the past eleven months I've been working on my dreads. Which is why I haven't dyed or done anything to my hair since. I decided after I started my journey that I wanted to just go natural so I wouldn't have to keep dying my dreads. I've never used bleach or anything of the sort before, so the thought was a bit nervewracking for me, particularly for use on dreadlocks (not being able to condition or anything afterwards). Then I heard about Colour B4. Today I did a strand test, coating a couple of dreads with it to see what would happen. After washing it off, nothing has changed. I'm thinking I maybe didn't use enough of the product, and tomorrow I'll be giving it another go and just covering as much of my hair as I can, and hopefully it'll go to plan. But I'm just a little worried.

I'm also curious about the 'Buffer' that comes with the product, wondering if that's safe to use on dreadlocks, since I only use residue-free shampoo on my hair, no conditioner, no wax, nothing. And if it is part of the colour removal process or is it simply a shampoo, and can I just cut it out. So I don't want to put anything unnecessary on my hair if I don't have to.

TL;DR my main question is simply, does anyone have any experience with using Colour B4 on dreadlocks?
I'm wondering if it's doable, safe, and will be effective on dreads, or am I just wasting my time?

Thanks for reading, I'd appreciate any help!