Just finished up my first run of house paint prints. Turned out great! I used a flat base but have read in various threads that a gloss or semi gloss is preferred. Why? Pure looks or for function? I did add about 25% speedball acrylic to darken and thicken things up. Did 130 prints 19"X25" with no gumming or clogging...without floetrol. Anyone else ever leave out the additives?