So, I want to make a red beer, what is the best malt to get this color?
One or two ounces of roasted barley is what I use to get that red color. My basic red ale has a crystal 60 and 120 in it as well. But its really the roasted barley in combo with those that gets you there.
EDIT: Here is a Red Ale recipe from Zymurgy magazine you can try. I don't know if you can get these ingredients or not however.
7lb Maris Otter Pale malt
3lb Munich 10L
0.5lb carared 20L
0.33lb Crystal 120L
0.25lb Roasted barley
1.25oz fuggles hops 45min
1.0oz EKG hops 15min
If all-grain isn't your thing; I suppose you could substitute ~5lb English LME for the Maris Otter and ~2lb of Munich LME for the munich.
Dark malts will give you that color. The problem is that you have to be very careful or you'll add too much roast/chocolate/bitter grain flavor. 1.5 - 3% of the grainbill to start out with; two or three ounces in a 5 gallon batch. Try pale chocolate or dehusked/debittered roast barley .
There's always food coloring too.
Trivia: All beer is red.
More information than you ever may want to know about beer color is in the 2009-11-16 episode of BrewStrong.
In first place it's very hard to get a blood-red beer. The beers that are said to be red are actually ruby, copper or reddish brown in color. Just to make it clear because you are probably aware of that.
My favorite malt for red color is Roasted Barley (in very small amounts - maximum 2% of your grist). Munich is probably one of the best too, and Vienna will create orange hues. There is one special malt called Red X that was created specially for its color.
Other caramel, crystal and dark malts may result in either red or brown color so be careful on your choice. Carared is okay for example.
Some alternatives are using food coloring, fruits or even beet.
I've used C90 for an ESB and the colour was a beautiful ruby. Also small amounts of Special B or C120.
All those answers above used to be the way to go. Since then, Best Malz has introduced Red X malt. It gives you the reddest color I've ever seen, especially if you use it as 100% of your grist.
Red X malt may give you that red color you're looking for, but it is way too malty,IMO. I've tried it in multiple quantities, from the whole base malt, to a few pounds of the grist, to a few ounces in the grain bill. Never been satisfied with the results. Personally I'd rather take my chances elsewhere
For the sake of completeness,
Consider using Melanoidin malt in your bill (used at 5-10% depending on the flavour you're aiming at).
Melanoidin will contribute rich malty sweetness to your brew and will help with that red colour you're looking for (but not on its own).