RUŌOD Lab

Level 8 · Performance Engineering and Evaluation

Longevity and Tenacity: Study Guide

Read our guide to tenacity on a blotter, then run a tenacity log on ten materials over a month and compare what you find with what the suppliers state.

Advanced 15 min study By the RUŌOD Lab team Updated

In short

Tenacity is how long a material stays perceptible, usually on a strip. The reference guide explains how to record it and what affects it. This study guide sets up a longer log than you have run so far, and it asks you to compare your findings with what suppliers state, which is often revealing.

What you will learn

  • Run a long-term tenacity log
  • Compare your own findings with published statements

Before this lesson: Projection, Sillage and Diffusion: Measuring the Unmeasurable

What to look for as you read

  • What the guide controls: dilution, dose, paper and storage.
  • Why a single number for tenacity should be treated with care.
  • How tenacity differs from longevity on skin.

Practical exercise: A one-month tenacity log

About 30 minutes · You will have: a tenacity log for at least ten materials over a month, with notes on where it disagrees with published statements

  1. Prepare strips of ten materials at the same dilution and dose, and clip them away from one another in a clean place.
  2. Smell them at 1 hour, 1 day, 3 days, 1 week, 2 weeks and 4 weeks. Record strength from 0 to 5.
  3. Note when each reaches 0 for you.
  4. Compare with any tenacity figures in the supplier documents or the encyclopedia.
  5. Note any disagreement, and suggest why.

You have done this well if your log states its conditions, and you treat your result as one person's observation under those conditions.

Knowledge check

1. What is tenacity usually taken to mean on a strip?
Show the answer

How long a material stays perceptible on the strip. Duration on a strip is the common working definition. Skin may differ.

2. A material vanishes for you on day 2, but a supplier says it lasts 300 hours. Why might that be?
Show the answer

Your sensitivity, the dose, the paper or a different definition of 'lasting'. Published tenacity values are method-dependent, and your nose differs.

3. What should you control in this log?
Show the answer

Strength, dose, strip type and storage. Those variables all affect how long the strip seems to last.

Further reading and materials

Written and reviewed by the RUŌOD Lab team. This is general education, not legal, regulatory, medical or safety advice. Example dilutions and exercises are for learning, are not validated products, and have not been safety-assessed. Completing a lesson confers no qualification. How we check these lessons.