I am so seriously jealous!! You lucky duck! Even if the insides don't work properly, $50 is a STEAL for that container. And if you can get it fired up working right--WOW. Congrats!
There are others that can weigh in here, but my bias is to keep the wood natural. I was mostly just giving my view. I do think that sealing the red wood would be counter to the real value of the breathing quality of redwood. Just my bias is all. I am not a wood worker but frankly think the real value of redwood is it's ability to hold moisture etc.
I guess I have less of a bias about sanding than I do sealing it.
They made these out of redwood for a reason - becase natural redwood and cedar are the only two woods than can handle the humidity. I had just read something the other night about how Leahy started the company in MO and how he was buying redwood by the train load to build these incubators.
I'll try to find the link to the story.
It was pretty interesting. The man knew an aweful lot about incubating and from what I read, he was pretty darn good at building, designing and using incubators.