I know it is kinda weird question but,

[Bassguitar man]

Few months ago I used some bleach on bed mattress and will it damage to my bass finishes?
Just curious. I'm sure it is dried.
My bass finishes tyed is gloss poly and matt finish.

 

[bholder]

When a bleach solution is completely dry, the active ingredient (chlorine) is gone (evaporated). Should be safe enough. Don't sue me if I'm wrong.