21D is a sample, not a batch. The record shows it clearly. Let me answer.

## What 21D is

21D (sample ID "LBN 21D") is one of six formulation samples derived from 9076 batch 21 (record exp-9076-021).

• Preparation (verbatim from the summary table): LBN 21 +4% mix xylene — i.e., the batch 21 resin ("LBN 21") with 4% mixed xylene added.
• Parent batch: "21" / "LBN 21". Batch 21's outcome is recorded as unknown (no application-test verdict in this drop).
• Downstream use: It is the direct parent of LBN 21E (LBN 21D +1% MIBK), so 21D feeds into the 21E variant.
• Batch-level remark (applies to the whole batch 21 block, not 21D specifically): "Strength/gloss for C black good/ Resolubility issue."

What the records do NOT contain for 21D: any of its own measured test values (strength, gloss, solubility, or application-test verdict). Only its formulation line and its role as 21E's parent are on record. Note this drop holds only *failed* application-test reports, so the absence of a 21D failure report does not mean it passed. There is no separate ELN/record for 21D — only its summary-table row.