Understanding beer color and SRM

Have you ever had an argument or maybe better to say difference in opinion over the colour of a beer? That this or that beer is or isn't actually a dark beer? If so we may have a solution; SRM.

SRM is the standard reference measure. A way of quantifying the colour of beer. More accurately how dark beer is. Both visually and in numbers.

The way this is done uses either photo light spectroscopy or a reference chart.

In the former case you have a pallet or swatch of sample colours. These are visually compared to the sample of beer and you get a match. That tells you what the SRM is is.

The former involves more advanced work and machinery but still reasonably available to even the average person.

You need a spectrophotometer and cuvette to to hold a sample of your beer.

Once in the machine you shine blue light at 430nm at the sample. The sample absorbs some light bt not all. The amount getting through is quantified. That is the base number needed. Now plug that into the relevant formula and you get the SRM.

SRM can also be converted into the European equivalent. In this case it is the European Brewing Convention. This is a reasonably easy conversion that only needs to be multiplied by a factor. To get SRM from EBC you just divide by the same factor.

Each kind of beer you brew will have certain SRM value relevant to the style you are making. Not a hard value but a range. Sometimes small and sometimes quite wide.