Here's why:
* Grams (g) measure mass (weight).
* Milliliters (ml) measure volume.
The relationship between mass and volume depends on the density of the substance. Density is the mass per unit volume (Density = Mass / Volume).
Hair color is not pure water, and its density can vary depending on the brand and the specific formulation. Some hair colors might be denser than water, while others might be less dense.
Because of this, you cannot reliably assume that 60g will equal 60ml.
In practice:
* Hair color instructions often provide ratios in grams or milliliters, and it's important to follow those instructions carefully.
* If the instructions specify grams, use a scale to measure the hair color.
* If the instructions specify milliliters, use a measuring cup or syringe to measure the hair color.
* Do not substitute one for the other unless the manufacturer specifically states that the conversion is accurate.
In summary, while the difference may sometimes be negligible, it's always best to measure hair color according to the units specified in the instructions for the best and most predictable results.