This is a professional back-bar developer for licensed colorists handling standard gray-coverage and moderate-lift permanent or demi-permanent color services — the strength that covers most everyday color formulas rather than services requiring heavier lightening.

It is not intended for at-home or DIY box-color use; Matrix sells and markets its cream developers for professional salon use alongside its own color lines.

The case for 20 volume over a stronger developer is proportional oxidation: it's engineered to give up to 2 levels of lift, which covers the bulk of routine gray-coverage and tone-refresh work without the extra lightening (and extra hair stress) that 30 or 40 volume would add where it isn't needed. It's the default strength, not the specialty one — 30 and 40 volume are reserved for services that specifically call for more lift.

Select the Matrix color line being used (e.g. SoColor) and mix it with 20 Volume developer in the ratio that line's instructions call for — commonly 1:1 for SoColor, though this varies by line and should always be confirmed against current instructions. Apply using standard professional sectioning technique and process at room temperature; Matrix's general guidance for SoColor-based formulas is 30-45 minutes, though exact timing depends on the specific formula and desired result. Always follow the packaged instructions for the color line in use.

• Confirm the mixing ratio specified for the Matrix color line being used
• Mix color and 20 Volume developer to that ratio in a non-metallic bowl
• Apply with standard sectioning technique
• Process at room temperature (typically 30-45 minutes, per the color line's instructions)
• Rinse, then shampoo and condition as directed

Pros:

• The most commonly used strength on a salon's back bar — handles the majority of gray-coverage and same-level-to-moderate color formulas
• Gentler oxidation than 30 or 40 volume, so less risk of over-lightening or unnecessary hair/scalp stress when only mild lift is actually needed
• Buffered, stabilized cream base gives consistent, controlled application

Cons:

• Not strong enough for services requiring more than 2 levels of lift — those need 30 or 40 volume instead
• Not interchangeable with other brands' developers — Matrix states substitutions can produce unpredictable results
• Requires correct professional pairing (color line and its specified mixing ratio) rather than a single universal ratio