I now have a complete, verbatim map of the Step‑1 phosphate charge for every block numbered 20–30 in the master experiment table (the only document that covers this whole range in one place).

How the P₂O₅ charge varied, batches 20–30 (all Step‑1 "phosphatisation" charges; values verbatim, no unit conversion):

• 20 — Phosphorous pentaoxide 8.24 g (with Butanol EO‑PO HV‑56, 226 g; 68‑75 °C, 4.5 h, N₂)
• 21 — 13.7 g (Butanol EO‑PO, 300 g Sunshield; 65‑75 °C, 4.5 h, N₂)
• 22 — 7.09 g (BEP‑1450, 150 g; 70‑75 °C, 5 h, N₂)
• 23 — 47.16 g (Sun Surfol R‑1400 HV‑56, 1010 g; 70‑75 °C, 4.5 h, N₂)
• 24A — 47.16 g; 24B — 4.5 g; 24C — 22.03 g; 24CR — 39.5 g; 24CR2 — 68.77 g (all P₂O₅ with Sun Surfol R‑1400)
• 25‑I — Polyphosphoric acid (PPA) 5.714 g (AV‑46 matching); 25‑II — PPA 12.39 g ("quantity as per patent" — a patent target, not a measured P₂O₅); 25‑A — PPA : P₂O₅ = 20 : 80, i.e. 1.071 g : 1.98 g; 25‑B — PPA : P₂O₅ = 30 : 70, i.e. 1.578 g : 3.67 g
• 26A — 20.95 g; 26B — 9.94 g (Sun Surfol R‑1400 HV‑59)
• 27A — 64.09 g; 27B — 64.09 g; 27C — 64.09 g; 27D — 64.09 g; 27E — 64.09 g (Vicasurf‑1010, 1700 g each — five repeats at the identical charge)
• 28‑A — 8.67 g; 28‑B — 13.1 g; 28‑C — 14.51 g
• 29‑A — 8.4 g; 29‑B — 8.4 g; 29‑D — 11 g
• 30 — 120 g (largest in the set; Sun Surfol R‑1400 2650 g, 3 kg sample to customer, R‑83)

Trend: No single monotonic pattern — the charge tracks the alcohol type and scale. Butanol‑based batches stay small (7–14 g); moving to Sun Surfol R‑1400 scales it up (4.5–120 g), and batch 30 is the clear maximum at 120 g. Batch 27 is a deliberate 5‑way repeat held constant at 64.09 g. Batches 25‑I/II use PPA rather than pure P₂O₅, and 25‑A/25‑B split the charge between PPA and P₂O₅ by ratio.

Gap note: Batch 24 has no single "24" block — the table lists it as sub‑batches 24A, 24B, 24C, 24CR, 24CR2 (plus a later "24 C‑I" at 20.95 g, which sits between 25‑A and 26A in the sheet and is ambiguous whether it belongs to 24 or 26). If you mean a single "batch 24," that record does not exist in the table.