Substituting Crystal and Amber Malts in Imperial Stout? And, how old is old?

[teadixon]

I'm looking at doing James Morton's 'Mad Boris Russian Imperial Stout' recipe, but I really want to use up open bags of malt I've got in the cupboard.

The Grain Bill is:

Maris Otter, 7 kg, 80%
Chocolate Malt, 700g, 8%
Crystal Malt, 350g, 4%
Brown Malt, 350g, 4%
Amber Malt, 350g, 4%

Hops: Colmbus CTZ
50g FWH
30g 10 mins

Yeast: US-05

A few questions:

I've not got any Crystal or Amber in, I do have the following - could I substitute any of these?
Roasted Barley, Pilsner Malt, Low Colour Chocolate Malt, Cara Rye, Cara Red, Carafa III, Munich Malt.

I've got some WLP004 Irish Ale Yeast - what would happen if I chucked that in? (I do also have US-05, but that's dry and my WLP004 isn't, so I'm keen to use the WLP004 while it's good.)

How old is old malt? I think my Brown and Chocolate Malts have maybe been open since October. I peg them shut, but they're not air tight. Are they going to be any good? How long is it worth keeping malt for once it's opened? My Maris Otter is all sealed and fresh.

Thanks!

 

[Fil]

afaik the colour and flavour elements of adjunts and specialty grains have a better shelf life than base grains as your not relying on them for enzymes which your base malts provide. So the remaining grains should keep well if you do buy. I dont think your grain stocks include anything comparable and with the 700g of black malt in the mix already your not looking for colour from these grains.. If you dont buy in perhaps simple ommsion is the answer, neither of the missing additions will add much in the way of gravity, but if worried you could simply add more base grain.

 

[MyQul]

You could use the cara red in place of crystal as I afaik think cara red is a low colour crystal. You could probably use munich instead of amber, although it's not really a like for like swap but I think it would be doable as amber malt imparts a biscuity flavour wheras munich is said to add a malty/nutty/biscuity flavour, wheras other sources say it adds a bready flavour

 

[teadixon]

Thanks @MyQul - I'll give that a go and see what happens!