Gum prints and humidity

Janessa, I've found that my cyanotype images are stronger (= darker) and punchier (with full highlight detail that is) when printing on thin papers. (Same for other iron processes such as argyrotype, pt/pd...) One good example to such papers is Awagami Masa (weight = something like 80-90 gsm). It's cheap, try and see it for yourself - you absolutely won't regret.