Litmus Paper - Correct Use | Professional beer line cleaning |Beer Saver

Check the Paper First Required

• Expiry date: Don’t use past shelf life.

• Storage: Keep dry

• Quick control test: Dip in a known alkaline solution (e.g., 0.1% KOH or a drop of weak NaOH cleaning solution). Paper must turn pink. If not, discard batch.

Correct Use Required

• Moistened test: Always wet the surface with clean water before applying paper (dry caustic residue won’t show).

• Dip test: When testing rinse water

• Avoid contamination: Don’t touch strip ends with fingers — oils/acids can neutralize the reaction.

Know the Detection Limits Required

• Phenolphthalein only shows pink at pH > 8.2.

o Below that, small traces of KOH may still be present but invisible.

o If your acceptance criteria are “zero caustic”, confirm with pH or conductivity.

Watch for Interference Required

• Buffers present? (e.g.

• CO₂ exposure: If rinse water sits exposed to air

• Dirty or oily surfaces: Can block the wetting of the strip — always swab with clean water first.

Confirm with Secondary Test (Best Practice) Required

• pH meter: More sensitive than strips for borderline results.

• Conductivity: Picks up very low residues quickly.

• Titration: For formal documentation of “mg/L as KOH.”

Action Plan if Paper Doesn’t Work Required

• Run the control test (step 1).

• If still no pink in a known alkaline

• If the paper works in control solution but not on site

Practical rule: Required

Use phenolphthalein paper as a fast “yes/no” check — any pink = re-rinse required. If no pink but you need proof of absence, back it up with a pH or titration test.

LITMUS PAPER INFORMATION GUIDE