I need to make some Nason (dupont) ful-thane arcylic urethane into semi-gloss. The p-sheet does not mention adding a flattening agent and there is not a flattening agent available in the Nason paint line. Dupont makes a flattening agent #4531s for imron and chroma 1. Will this work or am I just asking for trouble if I try it? The guy at the dupont distributor did not know. Has anybody ever had any trouble with flattening agents?