I steam bent some green ash chair parts yesterday. A set of turned rails for the back, and the back legs - shaved with drawknife and curved spokeshave.
Almost all went rather well, the only trouble I have is the presence of blue/black staining on the pieces after they come out of the steamer. This looks to me like the reaction of tannin in the wood with the steel from the tools, somehow "developed" during the warm wet steaming. It was not through contact with anything whilst in the steamer.
Although unsightly, it isn't very deep, and can mostly be removed by another working over with the spokeshave and a concave card scraper. Fortunately the back legs I had left slightly chunky to clean up after they were bent.
Do other people get this staining ? Is there any way of avoiding it, or is the clean up afterwards the best option ?