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中文 Glossary of defined terms

p-needle-penetration

P-04 needle penetration at 25 C

2026-10-09 · By The Candle Bench · Repeats 5×

The hardness number that decides a wick series. A weighted needle is dropped into a conditioned wax surface and the depth after five seconds is read in tenths of a millimetre. Five drops per specimen, spread at least 15 mm apart.

MethodWeighted needle penetration into a conditioned cast disc, median of five dropsRepeats5×equip4Quantities produced3Environment controlConditioned chamber at 25.0 +/-0.5 C; a second pass at 35.0 +/-0.5 C

Procedure

  1. 01

    Cast a 60 mm disc of the wax 12 mm deep in a flat aluminium dish and condition it at 25 C for four hours. The surface must be untouched and level.

  2. 02

    Bring the penetrometer needle to the surface so it just touches, with no deflection of the gauge, and zero the dial.

  3. 03

    Release for exactly five seconds, lock the needle, and read the depth in tenths of a millimetre. Wipe the needle with solvent between drops.

  4. 04

    Take five drops at least 15 mm apart and 15 mm from the dish wall. Report the median and the spread; a spread above 4 units means the disc cooled unevenly and is re-cast.

  5. 05

    Repeat the whole sequence at 35 C to give the high-temperature figure used in the wick sizing table.

Hardness is not one number; it is a temperature-dependent one, and the industry convention is 25 C. Two waxes at 25 C can reverse order at 35 C, which is why the burn log records the mushrooming rating separately: that rating is the practical hardness where it actually matters.

Needle mass针荷重
Drop time下落时间
Drops per specimen每牌号测点数

Instruments used

  • Penetrometer with 100 g loaded needleKoehler K19500
  • Aluminium casting dishes, 60 mm, level baseno brand
  • Conditioned chamber, +/-0.5 CMemmert IN30
  • Solvent wipes, low lintno brand

Sampling table

Disc diameter 60 mm
Conditioning before first drop 4 h at 25 C
Minimum drop spacing 15 mm

Quantities produced

  • Needle penetration at 25 C, 0.1 mmmedian of five
  • Drop spread, 0.1 mmover 4 units triggers a re-cast
  • Needle penetration at 35 C, 0.1 mmused for wick sizing

Environment: Conditioned chamber at 25.0 +/-0.5 C; a second pass at 35.0 +/-0.5 C

Protocols cited

No published burn report cites this protocol yet.