Sallyann1234,
Do you know any technical details about the stuff (I don't, which is why I ask)?
How much would you need for a really big stain that persists for a couple of days in a heavy swell?
And wouldn't it be affected by wind and current in the same way as debris?
And talking debris, how often does an aircraft end up in the water without leaving at least some debris on the surface anyway?
In the case of AF447 there was an entire tailplane... it still did not help in finding the sunken wreckage, leave alone the FDR and CVR.
CJ