dave...... said...
2) When rolling up to finish, grap both end of the wingtips, especially with one pump systems and then roll up. you roll once, and the sand is rolled up on the outside of the canopy, and not the inside..
Best tip I ever got - and it was from a teuro as well

See - they're not always useless twats. Just mostly
Next best was this one -
Before deflating tap and brush sand off the LE and out of the canopy with the
trailing edge pointing down. This will stop sand being collected in that worst of all places bw the LE & canopy.
So often I see people diligently bashing sand off the leading edge directly into an upturned, upside down canopy = directly into the seam line where it does most damage.

If you do both you will pack up a kite with next to no sand in the inside of the canopy.