Wine Tannin will improve the flavor of a dull wine. Tannin can be used with white wines that have not been exposed to oak to add astringency. Wine tannin can also add an earthy flavor to red wines. Use in conjunction with gelatin or isinglass for later fining as well.
It has work very well so far
I prefer this tannin to give a little backbone to dark fruit melomels like black currant, blueberry, and blackberry...easy to use.
The Tannin additive, not only adds a new palatable dimension to my wines, (Cab, Rose, and Pino Gris) it also balances the wine's characteristics. Note that, as always in alchemy, that it is advisable to do trials in order to determine the optimal amount to add.