Peroxide strength

[donna hair]

If I'm asking a totally stupid question please feel free to say so, but here goes anyway.

I've never understood how wella and Schwartzkopf offer 4% for tone on tone yet 3% is offered for permanent colours.

Like i say if it's a stupid question let me know but it's something that has always puzzled me

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[hairyh]

I have never understood that either,always wanted to know. Sorry cant be any help but interested to know as well. X

 

[hairyh]

I have never understood that either,always wanted to know. Sorry cant be any help but interested to know as well. X