30vol vs 20vol for roots

Peroxide vol is indicative of how active the oxygen in the mixture is--so 20vol is active less than 30vol, etc.  So the higher the volume, the more active it is, the more lift you ultimately get because the chemical reaction is stronger.

Also, as a rule liquid peroxide is more active than cream peroxide--but this also means it is much  more difficult to work with (particularly if you want to limit it to one area of your hair) and it has a strong reaction, so you have to work quickly with it.

Ahhh I see. Looks like I'll just have to speed up my application technique then! Thanks 🙂

If you're slow and the final bits aren't getting light enough before your time is up you can do half your head at a time. Do e.g. the lower half, wash out the bleach and start again with the top. You will wash out the coconut oil though so re-oil and wait an hour. This also gives you more time to section finely and make sure you get enough coverage, this alone can give you a lighter result.

For most people, 20/30 vol on roots actually has the same results since you have the heat from your head to speed it up.

Slightly unrelated, another reason that I've recently discovered is that hair gets stuck in the gold stage for the longest part of the lightening process. So even if you go a bit stronger, it takes so long to break through gold it doesn't make that much difference. This is why a lot of people going from black think that their hair stops going lighter! It really slows down when you get to gold.

My hair is naturally about a 7 ash blonde, and my roots go very pale yellow/white with 20 vol for 30 minutes. I'd give it a go and see what happens - it should go quite light. If you're getting any patchy processing, you can always warm that area a little (medium hairdryer over a towel for a very brief time, or sit near a radiator).

My next experiment will be trying the ammonia-free platinum paste on my roots to see if that will lift sufficiently without me having to use a conventional bleach. I'm going to do the bottom half first so if it all goes wrong I can cover it up :p: