The 2-1/4 gal of wort at 1.083, blended with 2-3/4 gal of the original raspberry brown ale (starting gravity of 1.070) in effect gives the equivalent of a wort with an original gravity of 1.076 -- definitely up to bock standards.
Notice that the 2-1/4 gal of blending wort was purposely lightly hopped. The grains were decoction-mashed with a high conversion temperature (158 degrees F/70 degrees C) to yield a dextrinous, malty wort. By itself, the beer resulting from this recipe would have been exceedingly rich, sweet, and full-bodied.
The resulting beer was wonderful! Rich and smooth with good body and a fantastic raspberry aroma. The flavors blended very well, the sweet malt perfectly balancing the fruity acids. The hopping rate, too, was right on, leaving little discernable hop bitterness and flavor. The hops were there, but definitely in the background, as they should be for the style.
The second wort was intended to deliver a raspberry porter (see box). I fermented 3-1/4 gal of finished wort for 17 days, then blended with 1-3/4 gal of raspberry brown ale. I bottled 1/2 gal of the original raspberry straight. The blend conditioned in glass at cool temperatures for another 12 days.
The 3-1/4 gal of wort at 1.063, blended with the 1-3/4 gal of raspberry brown ale (1.070) would yield the equivalent of 1.065 -- definitely high for a porter (by today's standards), but this recipe had to do double duty. Not only did this beer have to balance the acidity of the fruit, it also had to offset the sharp, coffee-like acids found in abundance in the dark malts. I kept the hopping rate low and again sought to achieve a dextrinous, sweetish mash. I used my modified step mash, resting at 156 degrees F (69 degrees C) for starch conversion.
The resulting blended porter was very nice. The black malts contributed a rich, roasty depth that beautifully complemented the fresh, raspberry flavors. The malty, underhopped sweetness was essential to successfully balancing the tartness of the brown ale.
Being naturally curious and always open to experimentation, I took advantage of the opportunity to test my theory further. I didn't have to make 5 gal of each of the two new beers. In fact it was more difficult to do so, requiring me to brew two blending beers in one weekend. It was important that the two beers be blended simultaneously, so as not to expose the original beer to more oxygen than necessary. I could have easily made a single 10-gal blend. The point is that volumes were not the most important thing -- preparing an appropriate blending beer was.
THE SALVAGE BLEND
Blending gave me the answer I needed. You don't necessarily have to settle for that disappointing brew. Monitoring your brew, catching an out-of-balance beer before bottling, and using the art of blending can produce a beer as fine as any other you can brew.
Blending is an art. I know of no way to use equations, mathematics, or measures (other than those used every day in recipe formulation calculations). The secret lies in tasting, evaluating, and using a little imagination. Identify the problem, design a beer with a complementary "problem," and blend the two beers into a harmonious whole.