I used to use lacquer flattening paste, but because of stupid clean air laws, we can no longer buy it here. for reducing epoxy from gloss to a very flat finish I mixed 50/50 flatting paste to epoxy. you will have to experiment with how much you need to get the desired finish, but after you get the flattening paste mixed with your varnish you may want to reduce it a little more and definitely strain it with a very fine strainer(like a piece of old panty hose). there are always little white dried bits of the flattening paste and they will wind up on your bow if you don't strain it after mixing in the flattening agent.