Cast Iron Rust Prevention?

My wife bought this bird bath that is made out of cast iron. Not really sure if it is meant to be a "practical" bird bath or not....it rusts almost instantaneously when it gets wet (of course...especially the bowl where the water collects...)
I tried putting like 3 coats of clear laquer on it...and that seemed to have absolutely no affect whatsoever. Is there a rust prevention product I could use in this case...one that is clear so as not to change to appearance of the bird bath?
Todd

Todd Rearick wrote:
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Fill the bath with phosphoric acid?

Todd Rearick wrote: (clip) Is there a rust prevention product I could use in this case...one that is clear so as not to change to appearance of the bird bath? (clip) ^^^^^^^^^^^^ I don't know about clear, but this is what I suggest. Line the bowl with fibreglass/resin, like you would use on a boat. You might add some lampblack to the resin so it does not look like a fibreglass lining. I would prime the rest with a good rust resistant primer, and paint it black. A flat or satin finish would probably look more natural on cast iron than gloss.