Compare production use rather than box price
Confirm the pad count and product identity first. Then track how many pads were issued, used, discarded or replaced during an agreed observation period. Keep startup trials separate from normal production so the comparison is not distorted.
A minimal batch worksheet
| Column | Entry |
|---|---|
| Identity | Supplier, SKU, lot and receipt date |
| Configuration | Lens / coating range, equipment and layer sequence |
| Quantity | Confirmed pack count and pads issued |
| Outcome | Completed work, repeated operations and observed failures |
| Commercial | Net price, freight, currency and delivery terms |
For a local cost comparison, divide the comparable delivered consumable cost by the number of acceptable completed jobs in that observation period. Record which other costs were excluded. Do not publish the resulting figure as a general performance claim for the brand.
Investigate changes before reordering
If outcomes differ from the accepted trial, check whether the lot, storage, preparation, lens mix or process changed. Do not attribute every failure to adhesive performance without evidence. Preserve failed-sample details for discussion with the relevant supplier.
State the reorder specification
Quote the approved SKU, outline, opening, pack count and configuration scope. Ask for available lot identification, shelf-life / storage guidance and notice of changes. Do not invent a universal shelf life; use documentation applicable to the actual consumable. Keep a small retained reference where your lab's procedure permits it.