The EVA pads on inflatable SUPs that are PVC tend to peel off. To re-glue it, you must use flexible PVC or Polyurethane glue.
Flexible PVC glues can be found at ship chandlers, swimming pool specialists or DIY stores. Consult the instructions for the PVC glue, to validate the ventilation and drying times:
1. Deflate the board
2. Clean the glue residue on the board and on the pads with a cloth and a little methylated spirit.
3. Pre-gluing: Apply a thin, even film of glue on both sides
4. Leave to dry
5. Coat both sides to be bonded again
6. Leave to dry for 2 to 5 minutes
7. Bring the 2 surfaces into contact and press
8. Put some old telephone books or other fillers on the pads to maintain pressure for the time of complete drying
9. Wait 24 hours before inflating the board