I check the weather forecast obsessively and don't take an H bag out if it sounds like rain/snow. I don't think I would take the chance with using a protectant product. I do use something to periodically clean/moisturize...a little Mustela baby cleansing lotion sparingly, only occasionally, on my black clemence Birkin, as it is used heavily. Have used it on a red clemence bag too. And vintage black box. The others I have left alone and would really only entrust an H store to do maintenance. I have heard of some other products people like...creme saphir? Meltonian? but have no experience with those. I would not put anything on a light-colored leather or Barenia for fear of darkening the leather...and would not put anything on any of the exotics. Amazonia I maintain with the wipes they sell, or a latex spray (don't ask where I bought that!)