Conversion of Peroxide Volume
Q: Could you please tell me the volume of developers converted into the percentages of peroxide (eg 3% = 10vol)?
For every 1% of peroxide in a reaction, 3.3 volumes of oxygen are released. So, if the solution of peroxide contains 3% hydrogen peroxide, its chemical decomposition will release 9.9 volumes of oxygen. We round this number up to 10.
Knowing this, we can convert the other standard developer strengths to their measure of peroxide percentages by simple division. Take the volume of the developer, and divide by 3.3. The result will give you the percentage of hydrogen peroxide in the developer.
For instance: 30-volume developer has 9.09% hydrogen peroxide in its solution. (40-volume = 12.12%; 20-volume = 6.06%; etc.) The formula for conversion does require some rounding off of the resulting numbers, but it gives you enough knowledge with which to work.
How to color hair
What does the developer do?
The formula to mix peroxide