There is nothing in the product itself to turn the hair yellow or orange, but blonde or white hair - either bleached or unbleached - has been known to turn yellow or orange for a variety of reasons. This could occur during the treatment and it may be outside your control. Causes could include type of color or treatments that are already in your hair, type of water, medication—even an aspirin can affect hair color! Another thing that can cause a problem is a flat iron that was too hot for delicate white or blonde hair. That is why the directions recommend starting at the lowest temperature on your flat iron.  Remember the goal is to get the hair silky.  It is simply a matter of adjusting the temperature only to the point where the hair gets easily silky. It is not necessary to do a lot of passes, generally no more than 3. If you elect to do the treatment again and if you should see the hair getting yellow or orange, STOP and turn the temperature down. DO NOT over flat iron the hair. Silky is the key word. Once it is silky there is no reason to continue to flat iron. If you should experience this issue, stylists with whom we discussed this question suggest that blue/violet based shampoo can reduce/eliminate discoloration as can a toner. Color or Toner may be applied immediately after the treatment and can be applied on the flat ironed hair if your hair feels light and silky.  Should your hair feel heavy or like it has extra residue after the treatment, simply wash your hair before you color it or apply a toner.