I wouldn't advise doing that unless you keep the aviary cage in a water-proof area with low humidity, as the hollow metal framing will rust out much much faster if you get water in it. Same goes for those who pressure clean their cages with water.
Those finch/canary aviary cages, in my opinion, would not be suitable anyway for a larger bird like a Hahns.
Probably better for you to just buy a roll of GAW aviary wire or stainless steel wire and build a custom aviary yourself. Pretty easy to do for anyone and cost effective too. And if you don't use a whole roll of wire, you will have plenty left to use again when MBS strikes. Or you could also sell the remainder of the roll to another board member who is in your area or driving thru one day.
You can order these rolls of wire in many sizes and you can order all the supplies you will need to construct it, like rings, latches, wire cutters, special pliers to close the rings, etc.
I was looking on ebay today and found this:
actually I bid on one today, a 26 x 20, it should be here this week! Not sure who's gonna go in it yet. 
but I only paid $80 (with shipping! talk about a deal!) 
