Dilution and Mixing Log

Educational guidance on registers and logs — what each records, who maintains it, what it typically contains and how long it is generally kept. Informational only — template examples, not official documents or legal advice; a register documents activity, it does not by itself prove compliance, and employers remain responsible.

What a dilution and mixing log is

A dilution and mixing log records when concentrated chemicals — cleaners, disinfectants, treatment chemicals — are diluted or mixed to a working strength, capturing the product, the ratio and who prepared it, because getting concentration wrong can be unsafe or ineffective.

This page is an educational overview with a simplified example. It is not an official template, not jurisdiction-specific and not legal advice — safe dilution, mixing and incompatibility controls depend on the products and the applicable law.

Purpose

• Record dilutions and mixes prepared for use.
• Support consistent, correct working strengths.
• Help prevent dangerous incompatible mixing.
• Provide a record where preparation must be controlled.

Who maintains it

• The person preparing the dilution or mix records it.
• A supervisor or safety lead oversees the process.
• The method follows the safety data sheet and assessment.
• The employer decides the process and who is authorised.

When it is used

• Each time a concentrate is diluted or chemicals are mixed.
• When a new product or ratio is introduced.
• During assessments and inspections of chemical use.
• When verifying working strengths.

Typical fields

• Product and its linked safety data sheet.
• Concentration or ratio and the resulting strength.
• Quantities prepared and any batch reference.
• Controls — PPE, ventilation, no incompatible mixing.
• Who prepared it, date and sign-off.
• Example columns only — adapt to your products and the applicable law.

Common mistakes

• Mixing incompatible chemicals, creating a dangerous reaction.
• Guessing ratios instead of following the instructions.
• Decanting into unlabelled containers.
• Preparing chemicals without the required PPE or ventilation.

Document workflow

A dilution and mixing log works with the substance chain: the chemical and COSHH registers cover the product and controls, preparation is recorded here, and any spill or reaction feeds the spill and incident records completed afterwards. Decanted solutions should be labelled.

See the related documents below for what is commonly required before and used with a dilution and mixing entry.

Retention (high level)

A dilution and mixing log is generally kept for a period set by the employer’s process and any applicable rules, long enough to support traceability. This page does not state a required period — confirm with the applicable law and the official authority.

Completing and sharing as a PDF

The log is often held on forms or in a system and exported to PDF. Exporting to PDF supports the record; it does not make it official or prove compliance.

Employer checklist

• Provide clear dilution instructions and prevent incompatible mixing.
• Require PPE and ventilation for preparation.
• Ensure decanted solutions are labelled.
• Keep the log linked to the safety data sheet and assessment.

Worker notes

• Follow the dilution ratio and never mix incompatible chemicals.
• Wear the PPE and use the ventilation specified.
• Label any container you decant a solution into.

Country considerations

Chemical handling, labelling and control rules vary by country and product, and the official authority differs. This page is general and high-level — not a statement of any country’s law and not legal advice.

Confirm current requirements with the official authority for your country and a qualified professional.

Who is responsible

The employer is responsible for the safe preparation of chemicals and for compliance. This page is an educational overview with a template example; it does not make a workplace compliant and does not transfer responsibility.