Test Media
D and G media
| D medium | G medium | |
|---|---|---|
| Home kit | Calcium carbonate powder, passing the #200 sieve (< 75 µm) | Silica (quartz) sand, such as play sand that passes the carbonate check, sieved into two fractions and blended 50/50 by mass: 150–425 µm (passes #40, held on #100) and 425–850 µm (passes #20, held on #40) |
| Lab kit | ISO 12103-1 A1–A2 blend | Same sieved blend as the home kit, from graded silica test sand |
| Preparation | Store sealed; use as supplied after sieving | Oven-dry at 105–110 °C for 1 hour; cool before use |
| Reuse | Discard after each full test | Re-sieve before reuse |
Note (informative): D and G use different materials because sealing (D) depends mainly on particle size, so a soft, low-hazard mineral like calcium carbonate is a reasonable home substitute. Mechanism damage (G) depends on particle hardness as well, so G uses real quartz sand.
Carbonate check
Home-kit sand that is not sold as silica sand shall pass this check before use.
- Drop a pinch of the sand into white vinegar.
- Watch for a steady stream of bubbles.
- Sand that produces a steady stream of bubbles shall not be used.
Note (informative): Some play sand is crushed limestone, marble or coral, which is calcium carbonate. It fizzes in vinegar and is much softer than quartz, so it would understate grit damage.
Ultrafine medium
A home tester who wants an ultrafine D medium (< 10 µm) shall buy a graded powder and record its datasheet particle size in the report.
Note (informative): Particles finer than 75 µm cannot be produced with hand sieves.
UV tracer
When a UV tracer is used, about 1% UV-fluorescent pigment by mass shall be mixed into the D medium. It is optional at the home tier and required for lab-tier D tests (see D: Dust).
The water used for W is defined in W: Water. Handling safety for all media is in Safety.