I’m brewing Russian Imperial Stout tomorrow. I’ve got 4 lbs of specially grains to steep before the boil. Do you think I would get more dark roasted flavor/color by cold steeping all night and then heating up to 155 tomorrow and holding for 30 minutes, or would that be too much and lead to tannin extraction? I did not buy extra grain to cold steep only.
I am not sure if you would get a lot more out of an overnight cold steep followed by a hot steep than you would with just a hot steep. The idea of the cold steep is to extract color only without any roasty character. Tannin extraction is a whole different animal and probably not a problem you will contend with in this brew
Steep 'em before the boil at ~155F.
In RIS (and in all stouts, IMO) you want that added acidity and acrid roast character.
Since you have so much to steep, I would either split them into 4 separate bags or (ideally) use a BIAB-style bag.