Dry = not sweet. Is this what you mean?
Aftertaste = the remaining taste that lingers after you're done swallowing the sip of beer. Is this what you mean?
My guess is that you're trying to tell us that there's a harsh quality to the flavor that lingers in the finish and aftertaste.
When I started with extract and partial mash brewing, my beers brewed with tap water often suffered from a sourish, tart, or harsh, astringent taste that lingered in the finish and aftertaste. My water profile was the problem (too alkaline, too much bicarbonate and sulfates). If you use your tap water, be sure to eliminate the chlorine and chloramines by using campden tablets and filter the water with an activated charcoal filter (very slow flow rates). Better yet, just use reverse osmosis water and brew salt additions. Also, don't excessively sparge the steeping grain bag. Soak it once, rinse it once (if at all). You may be picking up tannins from over-sparged grains. And don't use bleach to sanitize--the chlorophenols really can ruin your beer.
