Well Hello there!
Heard my name, so I figured I'd swing by! lol Just kiddin'....
Anyway Rowantree, there really isn't THAT much of a difference between the two. Sometimes more expensive salon brands use different ingredients/chemicals in their pigments than store bought color. Honestly the only noticable difference is that salon color may seem a bit deeper in color, and may stay in the hair a little longer. Thats about it. Color that is made in Europe tends to be a bit darker than US color. Like for instance, my mom likes an Italian made color cream - her hair is black - but she uses their dark brown, and honestly .. it's black. LOL (Looking at it anyway) The peroxide is the same... in salons the stylist can change the 'volume' of the peroxide, depending on your hair type. The higher the volume, the stronger it is - and more often - less time processing... which can be used on gray, or very resistant hair. Most at home kits are usually a 20 volume, give or take... which is pretty much all most people need... but then again - Its not very strong, which is why many home color kits tell you to leave it on for around 30 mins. Salons usually stock many colors that they can mix together to form a specific shade, where as at home kits are usually designed for one result (the color on the box) and you have to determine what your end result will be by considering your current color, porosity, past color applied etc. Sometimes the colorist at a salon will not determine your color correctly, and you end up with a result that you weren't expecting. Which could be why you weren't happy with the result. There are many things as to why it didn't come out correctly. You have to know colors and base colors and the hair to get what you want out of it. Which is why salon color is more complicated. You can pick "Sunset" off the sample board... thinking you'll end up with a rich red color.. but if it has a base of yellow - you could end up somewhat more orange than red... if you are already a blonde, or someone with gold tones. Home color kits are much more simple. Pretty much what you see is what you'll get. You just have to look at the charts they put on the box that shows before & after photos of the hair - and just consider the amount of red in your hair (if any) and realize that if you have red tones, they may show through along with the end result. Sorry if I'm confusing everyone, it's sometimes hard to explain. All in all, at a salon - the benefit is that the color is very detailed (you can add a 1/2 oz. of color A, 3/4 oz of color B etc) and you know what the base colors are. (So you know that if a person wants to tone down red, you find a color with a base of green... opposites on the color wheel) Negatives are that the stylist has much more room for error. They are pretty much chemists. Lots of ingredients, and to get the desired result, must be correct. Home kits... pro's - ease of use, outcome is generally what you see on the box.. any variations they will tell you about. (Results For red hair, more than 50% gray etc.) Pretty much only downsides are that they might not last as long...or if the person picks a TOTALLY wrong color (if someone w/ black hair buys blonde dye & expects it to actually come out that color - for example) Or if the person misses spots, leaves it on too long, or too short of time - those are pretty much the only downsides... people aren't professionals, and might make small errors. Home kits are good in the fact that most people have dyed their hair before at one time, and they know their hair.... they know how it reacts to colors... and if you get a color at a salon - most likely you will have to go back for the exact color again... being it's basically customized & you usually won't get a perfect match on your own. I would try some of the store dyes if you arent' happy with your salon color. I like the Garnier 100% color - it lasts VERY long.. like a salon color - & the results are great, very true to what is shown on the box. Just pick a color close to your natural color, or a shade darker or lighter. Home kits won't lighten your hair much... it has to be bleached of color first. But you can get some nice undertones by going one shade lighter. You can also use a "golden" color for gold tones, or a color with some auburn or red in it to give you some red hues. But... all in all - if you want one color, or suble undertones or natural highlights.. by all means, try an at-home kit. If you want something drastic - especially going lighter, or salon painted highlights... then I would go to the salon. (Sorry if this was so confusing!)