Don't know how accurate this is but I have seen a few posts on the net about making your own salt solutions to create a fixed humidity (curing your stuff)
The ones Ive seen seem to use distilled H2O sugar (dissolve into water first and salt (add 2nd).
Straight up saturated brine puts you at around 75% RH (too high).
Here's a copy of what I read. I flat out copied this it's not my work but it comes from another site so I'm not posting a link cause I'm not sure if that's a big no no here. I feel bad not giving him credit but what can ya do so thanks to
Jermamma420 for this work.
100 grams (ml) of distilled water
17.5 grams Sugar
70 grams of Non iodized salt.
Container (ball jar with outer threaded ring) with barrier. (Jar/Tyvek where the inner seal goes)
Completely dissolve sugar into 100 mL water. Add salt to create a saturated solution (still will be salt at bottom). Mark jar to show finished water level to give reference level.
The more sugar the lower the RH.
20g sugar= 51% RH
18g sugar= 60% RH
17.5g sugar= 62% RH
My thought is build a desiccator/Humidor with shelves and store your curing stuff in it letting the mason jar of this solution control the humidity.
Kinda like this but way way less fancy. Maybe a frame outta ripped down strapping with 1/8" luan/underlayment for sides and framed acrylic for a door???