Question about Kenyan sand boa humidity box

[Richtenhoffen]

Hello,

This is my first post on this web site and I just bought my second snake a wee Kenyan sand boa and I can tell its going to be a great snake (I dont know its gender yet people at the pet shop said its to small at the moment to check).

I have a question about humidity boxes in the cage and what kind of substrate I can use. Currently I have cypress mulch and plantation soil. Will any of these substrates work in a humidity box for the little guy?

Thanks