My down sleeping bag and down jacket have a conditioner built in to help the down repel moisture. Does anyone know if I can treat the outer shell with a rain guard like Camp Dry? I don't know if the spray just sits on the outside or actually permeates the down. I don't want to compromise the insulating values but would like to help protect them from condensation (sleeping bag ) and light mist, rain and the condensation of a rain coat (jacket).
Items advertising use of fully waterproof down are filled with a material that has been treated via a nanomolecular or hydrophobic coating that allows each tuft of down to resist moisture. I wouldn't worry about a spray-on treatment of the shell material having any effect. I might avoid a full wash treatment, however.
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