Saturated salt solutions

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Description

In a closed environment, saturated salt solutions can maintain an equilibrium with the moisture in the air. At low humidity, fully hydrated (liquid) salts can volatilize water. The solid salts can absorb moisture when the humidity is high. Saturated salt solutions are a low maintenance method to provide a constant humidity level within a display case (Eggert 2022). Unlike silica gel, which requires reconditioning, the saturated salt solutions only need supplemental distilled water added once a year.

Relative Humidity % at Selected Temperatures

Saturated Salt Solution Chemical Formula 68°F 77°F 86°F
Lithium chloride LiCl H2O 12. 4% 12. 0% 11.8%
Potassium acetate CH3CO2K 23. 3% 22. 7% 22.0%
Magnesium chloride MgCl2 6H2O 33. 6% 33. 2% 32.8%
Potassium carbonate K2CO3 2H2O 44. 0% 43. 8% 43.5%
Potassium nitrate KNO3 49. 0% 48. 1% 47.2%
Magnesium nitrate Mg(NO3)2 6H20 54. 9% 53. 4% 52.0%
Sodium nitrate NaNO3 65. 3% 64. 3% 63.3%
Sodium chloride NaCl 75. 5% 75. 8% 75.6%
Ammonium sulfate (NH4)2SO4 80. 6% 80. 3% 80.0%
Potassium nitrate KNO3 93. 2% 92. 0% 90.7%
Potassium sulfate K2SO4 97. 2% 96. 9% 96.6%

Table obtained from Technical Bulletin No. 5, Creating and Maintaining Humidities by Salt Solutions. Hygrodynamics, Inc.

Synonyms and Related Terms

salt solutions

Resources and Citations

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