I used this workflow.
1.scan an existing barcode on a third party list to create barcode number on an item using iPhone and adding number directly to a barcode field
2. Set up print list using blocks page designer
3. Added barcode field to list to be printed by clicking to add. No change in dimensions of field thereby added
4. Printed and tried to scan printed barcode with iPhone in the relevant table and view
5. Fails as barcode will not scan
Further test show barcode MUST be printed at 100% ( which it was) AND (this is much worse) stretched to a larger size in order to scan.
Result is a barcode printed output twice the size as the original barcode used to input into Airtable