A carefully conceived and implemented disc pressing procedure should give the analyst few difficulties. However, it is flying in the face of experience to assume that nothing can go wrong. The following pointers are essentially an index to this section of the Handbook, indexed by problem:

If the sample disc comes out of the die smoothly, but breaks. . .
• increase pressure, hold time, and/or bleed time (see “Technique for Pressing a Sample Disk,” p. 167).
• use Spec-Caps (see “Proper Use of the SPEX Certi-Prep Spec-Cap,” p. 161).
• use a binder (see “Binders,” p. 162).
• grind the sample finer (see “Key Points About Grinding,” p. 122).
• evacuate the die during pressing (see “The Use of the Vacuum in Pellet Pressing,” p. 168) .

If the sample disc is hard to remove from the die. . .
• use Spec-Caps (see “Proper Use of the SPEX Certi-Prep Spec-Cap,” p. 161).
• use a lubricant (see “Anti-Sticking Agents,” p. 166).
• prepare discs with a binder matrix (see “Sleeve-and-Plunger Technique: Binder as Disc Matrix”, p. 165).
• check that the bore of the die and the polished pellets are clean and undamaged; maintain or repair as necessary (see “Care and Maintenance of the SPEX SamplePrep Evacuable Pellet Die,”p. 159).

If the sample disc sticks to the polished pellet. . .
• put a thin sheet of SPEX SamplePrep Mylar, polypropylene, etc. between the sample and the polished pellet, before pressing (see “Anti-Sticking Agents,” p. 166).

If sample discs degrade rapidly in use. . .
• use a binder (see “Binders,” p. 162).
• evacuate the die during pressing (see “The Use of the Vacuum in Pellet Pressing,” p. 168).
• protect the spectrometer with SPEX SamplePrep XRF Window Film (see “Sample Disc Handling and Care,” p. 169).
• store the sample disc in a desiccator if it is to be retained.

If the polished steel pellets become scratched in normal usage. . .
• grind the sample finer (see “Key Points About Grinding,” p. 122).
• use polished tungsten carbide pellets, e.g. SPEX SamplePrep 3623C.

If the polished pellets become chipped or jammed. . .
• STOP IMMEDIATELY, and take corrective action to avoid
making matters worse (see “Care and Maintenance of the SPEX SamplePrep Evacuable Pellet Die,” p. 159).

To prevent further damage, always remember. . .
Never drop the pellets, or allow the edges to become dented.
Never tilt the pellets so that they become jammed when being placed
in the die. (If they become jammed, free them as gently as possible.)
Always put the squared-off end of the plunger into the die; if the
stepped/beveled end of the plunger contacts a polished pellet under pressure, the pellet can chip.