Is there any retarder for it?
Do you have any example of a "retarder" for any simple reaction? That's not a common chemical term. Yes, we do change the rates of reactions by changing conditions, for example pH or adding an inhibitor to say a biochemical reaction. But there's no big ol' book of reactions and their rate changers. Why do you include the water of crystallization with the oxalate -- because it will disappear in aqueous solution, unless this isn't an aqueous reaction. in which case, you have to explain it better.
, all members of this board can click on your profile, and read your previous posts. http://www.chemicalforums.com/index.php?action=profile;area=showposts;u=141863
Anyone can find out you're a marble-facing manufacturer, and you're looking to learn more about the chemistry of the various reactions that take place in your manufacturing production. But your application is esoteric, you can't expect that the problems you face are typical orgainic chemistry problems, just because they involve organic compounds. You're going to have to write out the complete problem, and hope someone in your industry understands them, and stops by.