Upload & Sell: Off
I'll usually try shooting ungelled or with a half gel instead of a full gel when shooting off warm wood surfaces. It's still a matter of experimentation. Sometimes it works pretty well. Other times it doesn't look so great. If I have a colored wall which I know will give me a WB problem, I might turn up the iso, open the aperture, but primarily lower the shutter speed so that the ambient light to flash light ratio is increased (i.e. ambient primary with flash fill instead of flash primary with ambient fill). Of course, that's only when the ambient light is sufficient in quantity, looks nice, and is not strangely colored .If you are going to be bouncing off the same wood surface consistently (a succession of photos will have a similar WB), then do your experiment with the flash on while bouncing off that surface, then choose which gel to use. Of course, if you do that you will not be matching the ambient exactly, but trying to match the combination of mixed light. Any gel you add to change the flash will only be partially effective because you are only changing the flash part of the mixture, while the ambient remains unchanged. Really, after a while you just wing it, because you will have a feel for what's needed and what works.