IS 303 and IS 710: what the markings on a sheet actually tell you
How to read the ISI stamp on a panel, and why a licence number matters more than the word 'marine'.
Two standards cover most plywood in Indian supply. IS 303 covers moisture resistant and boiling water resistant grades — the ordinary interior panels. IS 710 covers marine grade, tested to a stricter regime of prolonged boiling.
The distinction matters because 'marine' is a word anyone can print on a sheet. A genuine marine panel carries an ISI mark showing IS 710 and a CM/L licence number tied to the manufacturer. If the sheet says marine but carries no IS 710 mark, it is a description rather than a certification.
The stamp usually also records grade, bonding type, thickness, sheet size, batch number and manufacturing date. That is your traceability: if a query arises two years later, the batch number is what makes it answerable.
It is worth photographing the stamp on delivery. It takes ten seconds and it is the only record of what was actually supplied, as opposed to what was ordered.
