From The Collaborative International Dictionary of English v.0.48 :
Rubberize \Rub"ber*ize\, v. t.
To coat or impregnate with rubber or a rubber solution or
preparation, as silk.
[Webster 1913 Suppl.]
From WordNet (r) 3.0 (2006) :
rubberize
v 1: coat or impregnate with rubber; "rubberize fabric for rain
coats" [syn: rubberize, rubberise, rubber]