Catt - you and I will perennially have some level of disagreement on this, I suppose. I'm not saying that's a bad thing - a matter of degree only. In this case, I have to ask that if urea is so good of an orchid fertilizer, why is it not commonly used?

Now, to contrast that, I know a superb paph grower in Canada who swears his plants do better when a tiny amount of urea is added to his nitrate/ammonium stock... I have no basis to agree or disagree with his assessment, but his watering does include leaves, so what I've read about urea and its preferential absorption through leaves might apply there..

You are correct - the articles I have read stated ionic in character, not strictly a matter of polarity - both of which, of course, vary in degree...