Boxed semi-permanent colour or low volume peroxide?

I think the only difference between the box dyes at the drugstores and colour + peroxide you'd get at Sally's is the "arbitrary" comment you got from L'Oreal... I've heard that box dyes use a much higher volume peroxide than you actually need with the dye, so they cause much more damage than if you buy separately and control the strength of peroxide.

I agree though, it's much cheaper to pick up a box dye, and I don't have a Sally's card either!  But if L'Oreal won't tell you, or they don't know for sure, then it's definitely safer to pick the strength yourself and know what you're using.  Sadly, the difference between 20-v and 30-v is quite a lot in terms of the damage it can do to your hair.

Thank you, I feel a little better about spending so much money!  I'm wondering if I should go with the 10 volume peroxide instead instead of 20.  I don't need much lift though I have some grey and my roots are a level or two darker.  Is it the volume of the developer that makes a colour permanent vs semi- permanent? 

I contacted Loreal to ask what their peroxide volume was but they wouldn't tell me.  They said the amount of peroxide was arbitrary, whatever that means!

It sounds like the person you spoke to thought you meant volume as a measure of space, not strength, so the amount of peroxide in each bottle is arbitrary (random).

Demis tend to be 10 or 20 volume in boxes, boxed permanents tend to be 20-40 volume, depending on the shade.

If you just want to deposit colour (ie tone on tone) you only need 10 vol peroxide tops. In Sallys etc you can get even lower volume peroxide called 'colour releasers' that are designed for these types of dye. No lift and minimal damage, they are much safer on bleached/damaged hair.

Thank you everyone.  I went to Sally's today and picked up a bottle of 10 vol peroxide.  When I'm ready to dye I'll test a piece of hair using 10 and another using 20 and see how it goes. 

Stingle,
What you pay at Sally's as a non-trade customer is still worthwhile, I know it sounds a bit pricey, but you have the control on what the product you choose does to your hair now, and it's worth paying that bit extra to save your hair. I used to buy Sally's own branded products and when I moved on to more expensive stuff the difference was clear. It's always worth doing some research on products and paying that bit more for peace of mind and minimal damage.

If L'Oreal are being vague about their products and don't have the confidence to tell you what they have used, you have to question whether their product is worth using.

Ok I tested two pieces of hair, one with my hair colour mixed with 10 volume and one with 20 volume.  It's not a huge colour change on my lengths so I didn't see much difference either way, but on my roots the 10 volume barely did anything at all.  I could see a difference with the 20 volume.  I'm not exactly sure what to do now!  My roots are a couple shades darker than the rest of my hair.

Update - I went ahead and dyed my hair with the 10% volume peroxide.  I used Goldwell Topchic in medium copper gold mixed with berry - all a level 7.    It took 3 tubes of colour!  When I did my test piece I must not have used enough product because the 10% lifted my roots like a treat and the rest of my hair is a pretty even colour.  I didn't apply the colour to the ends and the more damaged bits till the last 10 minutes.  I can use Adore dyes like Cajun Spice to keep the colour bright - all in all I'm pretty happy with my hair for the first time in months!

So glad that it turned out well!