How long to become waterproof again?

[catroo]

I took my little hairies to a show last weekend so they had a full bath, how long before their coats become water proof again? They don't normally wear rugs but as it's been raining really hard they've had a rainsheet on to stop them getting water logged but it's a bit warm for that really.

 

[WelshRuby]

I think they should be waterproof now as it's been almost 7 days since their baths. After mine has been bathed his coat is usually starting to feel a bit greasy and look a bit "dusty" after 4 or 5 days.