>>Polyurethane is safe AFTER it has completely cured and is not producing any detectable fumes. Try closing the cage and wait an hour and then open it and put your head in and see if you can small fumes. If you can you need to wait for it to cure longer.
>>
I would even wait longer. With the heat on to help cure the finish, cover any vents, wait several hours and if you can smell the slightest smell of the polyurethane, it still needs to cure longer. Open the vents, wait a day, cover them again for a few hours and smell again. Repeat as many times as necessary until you don't smell anything, then open all the vents to let it cure another day or two just to be safe.
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Thanks,
Dave Colling

www.rainbows-r-us-reptiles.com
0.1 Wife (WC and still very fiesty)
0.2 kids (CBB, a big part of our selective breeding program)
LOL, to many snakes to list, last count (02/01/2010):
42.61 BRB
27.40 BCI
And those are only the breeders 
lots.lots.lots feeder mice and rats 

