I thoroughly messed up my sleep schedule this weekend making cold brewed coffee, so I thought I may as well share in what I learned the hard way.
1. Most recipes are for lighter, or at most medium, coffee. On day 1, all I had in my cupboard was dark roasted, which produces an absurdly powerful concentrate when you follow the same recipe.
2. I hate mixing mass and volume, so my master ratios are (for now) 150g of light roasted coffee per liter of water, or 100g/L of dark.
3. Two-stage filtration works the best, because there is going to be a LOT of sludge at the bottom. Pour through a fine sieve to capture the grounds first, then through a coffee filter to get the silt.
4. Too much coffee grounds will clog your sink. Wipe up excess with a paper towel and throw it in the trash.
5. Don't use the cone-shaped coffee filters. I thought that would be perfect for pouring through a funnel into a soda bottle, but it turns out the coffee sludge clogs up conical filters way too quickly.
6. Rinse out the sieve you used in #3 above, then lay a large coffee filter inside of it and pour through in spurts. You may have to go through 2-3 filters for a liter, because the coffee sludge will clog up even a large filter.
7. Don't try to squeeze the sludge through the filter as it clogs up. You might tear the filter and have to start over from the beginning.
8. 12 hours of steeping is sufficient, but 18-24 is better, even for the dark roast.
9. Dilute the concentrate at least by 1:1 with water or milk; you can use less cream, but I didn't have a good measurement.
10. Based on my physical reaction, I'd say the cold brew has plenty of caffeine. I stayed up 41 consecutive hours after testing my first batch.
Still to be determined: I usually see steel or glass containers recommended for steeping, but I used plastic water/Gatorade bottles without ill effect. I did not test if the coffee flavor leeched into the plastic, though one of them did stain slightly brown after steeping, so it seems plausible.
That's all, folks. Now excuse me while I bounce off the walls for a bit.
"I've always thought pastrami was the most sensuous of the salted cured meats."