EducationJuly 25, 2026by Chase2,603 reads

How to Read a Reagent Test: The Complete Visual Guide to Interpreting Results

Reading a reagent test correctly requires more than matching a swatch. Reaction speed, lighting, sample size, and reagent age all affect your results. Learn how to get reliable readings every time.

Three Dimensions of a Test

  1. Color, what shade appeared
  2. Speed, how quickly it developed
  3. Progression, how it changed over time

A slow Marquis reaction tells a different story than an instant one.

Reading Color

Use a white ceramic plate, white LED flashlight, and wait the full development time. Screen colors never match exactly, look for reaction categories instead of exact shades.

Speed Reference

Instant (<5s): high concentration. Fast (5-30s): typical. Slow (30s-5min): low concentration or degraded reagent. No reaction after 5min: not present.

Color Progressions

Marquis on MDMA: Purple to black. Mecke on MDMA: Green to dark blue. Ehrlich on LSD: Pink to purple (3-5 min). Froehde on MDMA: Greenish to blue-black. Always wait the full time.

Common Mistakes

Too much sample, wrong surface (ceramic only), poor lighting, not recording results immediately, testing mixtures without expecting combined reactions.

Photographing Results

White background, white LED light, include reference card, shoot at 10s/30s/2min/5min, include reagent bottle in frame.

Trust Guide

Fresh reagent + textbook color = high confidence. Old reagent + unusual color = replace reagent. First time using reagent? Practice on a known sample first.

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