Sat Oct 02, 2010 7:33 am
Color can be a complicated subject but in fact the basic principal is quite simple. All beer is inherently red because it transmits light of long wavelength more than light of short wavelength. The more color absorbing material the light interacts with, the redder the beer appears. Thus even pils looks reddish if you put a light source on one side of a carboy and look at it from the other. And, by the same principal, stout, even the "blackest" looks red if you shine a flashlight through an inch or less in the bottom of your glass. This works because beer optical absorption spectra are, regardless of the intensity of the color (darkness of the beer) all essentially shaped the same.
So to make beer look redder, you add coloring material. This can be done by using dark malts or by longer boiling or by using decoction mashing... The ultimate in color control is, I suppose, Sinamar, a product sold by Weyerman which is an extraction of the coloring material from roast malt. It is now sold in the US in small quantities (and a little goes a long way). To get redder beer you make darker beer by adding more dark malt or more Sinamar. The trick is to get it dark enough that it is red but not so dark that the red can't be seen. I mentioned stout earlier. It looks black even though it is, in reality, red. I guess I'd say beers between 10 and 20 SRM could be considered "red" so I'd shoot for something in that range bearing in mind that you can't rely on the various color models to tell you exactly what color you will hit anymore than you can rely on them to tell you how bitter your beer will be. What the models are good for is getting a starting point around which you will have to experiment to get exactly what you seek.
Now is it possible to have two beers with the same SRM and have one redder than the other? Yes, it is. Fullers ESB and Boom Kriek have the same SRM but the Kriek looks much redder. This is, of course, an extreme example. The redness of the Kriek comes from the cherry juice. In all malt beers there is some variation as well but it is not nearly as dramatic. I have no idea as to what one should do if he wants to redden beer at a given SRM so that it is redder than typical. I saw somewhere that residual bicarbonate tends to produce redder beers but I have no supporting data. Few people actually measure color and when they do it is usually only at the one wavelength (that determines the SRM) whereas a complete color description requires additional measurements.
