Paint colour conversions

There are often colour conversion charts in books, there is a software package (TCS) dedicated to colour conversion and several conversion books. Americana offer an online conversion, and Jo Sonja recently published one in Artists Journal magazine. make a collection...However, while all these are useful I still find that they are not always satisfactory, and you can often mix 2-3 colours in one brand to match a colour in another. The colours will be similar or a close match, but never exactly the same. Sometimes all that mixing may well have been avoided by simply substituting a near match straight from a jar or tube. For example a conversion for Jo Sonja Teal green to Americana is Hauser Green dark and deep teal. Depending on the project I will often use just either the Hauser green drak or he Dep teal. The problems get further complicated when a project may mix teal green with another colour to make a different green...you could then end up with 4-5 colours in your conversion mix! So...I tend to look at the conversion and check that with my eye...is that the colour I want for there or can I substitute it? So...conversion (closest Match) are great and sometimes very useful...but substitution (a replacement colour) can also be a way around buying another bottle or tube just for that little bit there.