I'm not familiar with those creels, however I am familiar with caned chairs= .
Unless someone, here, knows for sure....
A gentle washing with a soft brush, mild soapy water and rinse well shouldn= 't bother the bamboo. I would suppose it gets wet when fishing, anyway. T= he water may soften the bamboo, as it does with caning. If it softens too = much, you might want to stuff the creel with bundled news print to maintain= the form/shape of the creel, while drying.
Caned chairs are finished with shellac, usually. Maybe test a small area w= ith a more water resistant finish, should you decide to put a finish on the= creel. I have no idea if creels would have a finish on them, or not.
I use Frank's Cane and Rush Supply for my supplies -
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inquire of them or a supplier near you, for expert advice specific fo= r bamboo. A good sporting goods outlet may know, also.
Sonny