Argo Gloss Laundry Starch is ideal for priming translucent drops as it does not opaque the fabric the way paint will.
Dissolve one pound starch in one gallon of cold water. Then slowly pour the starch into three gallons of boiling water, stirring constantly. Dip fabric to be primed into warm starch solution. 4 gallons covers approxiately 400 sq ft of muslin.