Hi again....Ok, this is the tip I got from the Salon I used to buy from, in Dublin [ I live 160 Miles from it near Cork city, so when I had colour-matching issues, in between visits, I needed to be able to do it myself] System hair [normally] is chemically treated at the factory, and the outer layer/skin [can`t think of the exact word] is stripped off [ In the case of Toplace hair this may not be the case....maybe John will enlighten us ! ] but a lot of places do `treat`the hair before venting into the bases.... if you apply colouring products to it, it tends to really `grab`the colour deeply so you shouldn`t leave it on for more than 2 or 3 minutes at most or it will go too deep/dark, whereas your growing hair takes longer to absorb colour as it still has this outer [resistant] layer so you need to leave it in for about 15 minutes or so to get the same depth of colour...... system hair tends to be dryer than growing hair obviously, so even if it hasn`t been chemically treated at the factory, it will still `grab`the colour more quickly than growing. If you want to use something stronger than Back2natural, such as normal colouring products used in Salons, bear those points in mind. I just bought a tube of Black and a bottle of Creme Peroxide, mixed them into a paste and applied carefully while wearing rubber gloves....I have also applied using a comb... my own hair is pretty thin so simply back-combing the colour in, is easy.... I have applied it to system hair too [not my present system] mostly around the perimeter [for a good blend with the growing] and more sparingly in the middle...the trick is not to leave it in long and try to keep it off the base material if at all possible or it will stain it and be noticeable... rinse it off by allowing water run through the base onto/down the hair by holding it upside down under the running water.... hope that`s of interest. Finally I think the Toplace systems are made from `Remy`human hair which is not chemically treated and is the nicest hair..keeps a nice texture...John can tell us anyway, just as a matter of interest... Paul.