Italian tubular glue is typically enough for mounting two tubular tires.
Packaged similar to toothpaste it is easy to apply and dries clear.
It is advised when mounting tubulars for the first time on a pair of
new rims to put a base coat on the rim. This will effectively cause you
to use more than on 2nd or 3rd mountings but reduce the chances of a
tubular slipping off. We Keep You Cycling recommends you
purchase 2 tubes of glue.