Preparation of Saturated Salt Solutions - W/O Being Wasteful

**Question**


What is the most cost effective way to prepare saturated solutions of each of these compounds? LiCl, K2CO3, and NaCl. 


**Background**


I am trying to create a rudimentary controlled humidity device within my lab. I am essentially taking a desiccator, removing the desiccant, cleaning thoroughly, and inserting various saturated salt solutions in order to have a controlled vapor pressure of water above the surface of the saturated solution; assuming there is a constant temperature.


I have included a temporary link to the two journal articles I am using to try and accomplish this goal, but I will try and give all the relevant information here as well so people don't have to go and check out my shadylinks.[Dropbox w/ journal articles](https://www.dropbox.com/sh/mtp3vlw0lepb5wp/AACv6qzu0YOXSwrS-cI8G15Aa?dl=0)


I have the salts needed to make up solutions of LiCl, K2CO3, and NaCl. They were quite expensive for our small research group though and I don't want to waste any materials. The volume in the bottom of the desiccator is about 200mL and I have 100g of each salt to use for the course of the short experiment.


I know that a saturated solution in general chemistry is simply prepared by dissolving as much salt as is possible into a heated solution and then cooling it. However, as I have been reading some of these papers there are many reports of non-diffusing barrier layers on the surface of many saturated salt solutions. This means that the relative humidity of these solutions changes a significant amount over time. Some papers report the use of "slurries" or "sludges" in which just enough water is added to a pile of salt in order to make it appear damp.


I have also read that the preparation of a saturated salt solution is very dependent on the relative humidity which is established by that salt solution. More specifically, that low rel. humidity saturated solutions might need the slurry approach and higher rel. humidity solutions favor the standard saturation techniques. However, I have no idea what the cuttoff for "low" and "high" is and I am left to assume it's whatever the atmospheric humidity is. 


I am more than happy to do the legwork and read up on as much as need be, and I am still doing so as this post sits. I just don't know where to go or how to approach the question of how much saturated solution, or how much slurry, will be enough to control the humidity inside of about a 1L container. I can't afford really to go about preparing the solutions in order to find the best method experimentally and I was really hoping there were some experienced people out there who could point me in the right direction.


Thank you for all of your time reading this regardless of response! It is much appreciated!


