Saturated salt (vis-a-vis Boveda) cigar humidifier, 75% RH (when used w/table salt)

thingiverse

A reusable saturated salt humidifier (vis-a-vis Boveda) utilizes the humidification properties of a saturated salt solution in equilibrium. **Important update 7/11/2019**: I believe I traced down the source of the leaking at what I had assumed was the bottle cap. Upon closer inspection, I determined that the leak was coming from the very base of the thread where it attaches to the main body. To combat potential leaks in this area, I've reinforced this area with a raised boss. While this change reduces the thread capacity, it still leaves plenty of room for a standard bottle cap. However, if absolute water tightness is required, I do advise the use of a 28mm "sealed for your protection" bottle-cap seal (as found on vitamin bottles). They should be pressed into the bottle cap first, then tightened where it will activate the adhesive. They are slightly oversized for the purpose, but this has been the best size to ensure a good seal. After some long-term testing, I have two points of caution: * **Please test each of your prints** for at least a week, preferably two. Out of the 13 test units I printed, four of them developed slow to major leaks. Three of them were non-obvious and would've passed a visual inspection, and the fourth was a result of poor layer adhesion. * Even if you believe you do not need a water-tight seal at the cap, **I'd still recommend the precautionary use of a bottle cap seal**. Three out of my 13 test units developed "salt-creep" during long-term testing, where salt climbs up the vessel and outside of it. **Features:** * Maintains 75% RH across a wide range of temperatures * Uses only salt and water * Uses a standard bottle cap to service * Deep well below cap allows easy inspection for undissolved salt * Easy to gauge maximum water fill - proper water fill level maximizes surface area for responsive RH regulation * Gore Tex fabric frame elevated to keep above the surface of the salt solution * Tested to be watertight when left upside-down overnight (keeping right side up recommended) * Designed to be printed with internal support that's easy to remove **To use:** * Remove cap and fill w/water to bottom rim of fill hole (exception: use less for humid climates) * Add salt through fill hole and totally dissolve; repeat until salt no longer can be dissolved * Add additional salt to provide "a backup charge"; the added salt should settle to the bottom and be visible through the fill hole - for proper operation, always maintain some amount of undissolved salt * Replace cap **To maintain:** * Simply open cap and ensure there is both: + Sufficient water (though no higher than the bottom rim of fill hole) + Undissolved salt in the salt well (the deep well directly below the cap) * Add either as needed to maintain water level and presence of undissolved salt, though other than loss through spillage you shouldn't need to add any additional salt beyond the initial charge when first setting up **Table of RH w/various saturated salt solutions:** - https://bio.groups.et.byu.net/EquilibriumSS.phtml Bottle thread was based upon Vijit's 25_bolt.stl https://www.thingiverse.com/thing:3533967