After bleaching my hair and ending up with too much yellow, I went to Sally's and bought the recommended Toner ( Wella ColorCharm T14) and Wella Cream Developer vol 20. Just before mixing I glanced at the ingredients of the developer and found that it contains an ingredient- Salicylic Acid- which I am extremely allergic to.
My question- Since I have already bleached my hair and basically only need toning, can I use something like a small amount of hydrogen peroxide to activate the toner?
yes, you can use a 10 vol peroxide instead. The only reason they recommend the cream developers is because they are supposed to be more gentle but a low level peroxide should be fine. I would say 20 vol is too high for a toner.