Oh and Maude - thanks for top advice!
yeh, Steve at Manchester Guitar Tech had good instructions about cold wet weather blooms... and you know in the end I’ve risked doing it indoors. I get a good seal on the door in the room (bed sheet wrapped around it and a blanket across the bottom), windows wide open, I have a proper vapour mask which is 100% effective... and all the junk in the room (including vintage basses 😱), well it’s only dust. They are getting a little dusting but it is dry and brushes off.
My wife ain’t that happy but she’s putting up with me... so long as I don’t spray in the evening. There is a bit of a whiff for 20mins after I’ve opened the door, but it’s very slight.