SECTION 1 - DETERMINATION OF TOTAL ASH
Scope
This method is to be used for the determination of total ash of waxes, wax blends, rosins, and similar materials. (Alternative method is with microwave ashing unit see test procedure Microwave Ash Furnace Method)
Definition
Total ash is defined as a percentage weight of residue after complete combustion.
Equipment and Materials
  • a. Crucibles: High form quartz crucible (Figure 1) or Coors High Form Porcelain Crucible #230, size 1A or 2
  • b. Analytical Balance - Any suitable balance having a sensitivity of 0.1 mg
  • c. Muffle furnace capable of reaching and maintaining 1800°F ±25°F or Meeker Blast Bunsen Burner
  • d. Desiccator with suitable desiccant
  • e. Crucible Tongs
  • f. Clay Stem Triangle, and Ring Stand
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Figure 1 - High Form Quartz Crucible
Safety
This test requires extreme care due to the use of open flame burners and a high temperature muffle furnace. Proper PPE is required (heat resistant gloves, eye protection and protective clothing when handling hot crucibles, and molten wax). Use proper ventilation. Have a properly rated fire extinguisher nearby.
Sample Preparation
  • 1. The sample shall be thoroughly representative of the material under test. (Three tests required per determination.)
  • 2. The sample shall consist of freshly broken small lumps, pastilles, flakes, or powdered material.
Procedure
  1. Determine the tare weight of the crucible, either quartz or porcelain by:
    1. Heating it to 1800°F on the Meeker Burner for 20 minutes.
    2. Cool in the desiccator to room temperature.
    3. Weigh on the analytical balance to nearest 0.1 mg.
    4. Repeat 1–3 until two consecutive weighing agree within 0.1 mg. (CW1)
  2. Place the sample in crucible, weighed to nearest 0.1 mg in porcelain or quartz crucible. The sample weight is 10–20 g. (WS) (Figure 2)
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Figure 2 - 10–20g Sample in Quartz Crucible
Procedure(Continued)
  • 3. In an exhaust-ventilated fume hood, place the crucible on a clay stem triangle on a ring stand, and heat with a Meeker Blast Bunsen Burner until vapors continue to bum spontaneously. Protect from drafts and allow to burn until all volatiles are burned off. (Figure 3)
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Figure 3 - Crucible on a Clay Stem Triangle on a Ring Stand Diagram
Procedure(Continued)
  • 4. When all volatiles are burned off, either: Transfer the crucible to a muffle furnace which is heated to 1800°F and hold at this temperature for 20-30 minutes until ignition is complete or tilt the crucible on the clay stem triangle to 45° and heat with the Meeker Blast Burner until ignition is complete.
  • 5. After ignition is completed, transfer crucible to the desiccator. Allow it to cool to room temperature. Weigh to the nearest 0.1 mg. CW2
Calculation
Percent Total Ash = (CW2-CW1) / WS x 100%
WS = Weight of Sample
CW1 = Tare Weight of Crucible
CW2 = Weight of Crucible + Ash
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