RH boven verzadigd zout

How to use saturated salts for calibrating instruments
The dry salt is spread about 3 mm deep in a shallow tray that occupies most of the bottom of an airtight box. Water is added to moisten the salt. Do not add more water than is needed to make the salt look damp. The instrument is then laid on a grid supported above the tray. Electronic sensors can be inserted through a hole in the box which is made reasonably airtight with a split rubber bung. Allow one hour for equilibration when the instrument is bulky. 20 minutes for small sensors.
Note that saturated salts that have equilibrium RH below ambient will continue to absorb water indefinitely and overflow. The 98% RH calibration can only be done in a room with constant temperature.

Salt/T	5.0	10.0	15.0	20.0	25.0
Lithium chloride	11.3	11.3	11.3	11.3	11.3
Magnesium chloride	33.6	33.5	33.3	33.1	32.8
Potassium carbonate	43.1	43.1	43.1	43.2	43.2
Sodium bromide	63.5	62.2	60.7	59.1	57.6
Sodium chloride	75.7	75.7	75.6	75.7	75.3
Potassium chloride	87.7	86.8	85.9	85.1	84.3
Potassium sulphate	98.5	98.2	97.9	97.6	97.3

Salt	Temperature ^oC
	15	20	25	30	35	40	50	60
	Relative Humidity %
Potassium sulphate	97	97	97	96	96	96	96	96
Potassium nitrate	94	93	92	91	89	88	85	82
Potassium chloride	87	86	85	84	83	82	81	80
Ammonium sulphate	81	81	80	80	80	79	79	78
Sodium chloride	76	76	75	75	75	75	75	75
Sodium nitrite	-	66	65	63	62	62	59	59
Ammonium nitrate	69	65	62	59	55	53	47	42
Sodium dichromate	56	55	54	52	51	50	47	-
Magnesium nitrate	56	55	53	52	50	49	46	43
Potassium carbonate	44	44	43	43	43	42	-	-
Magnesium chloride	34	33	33	33	32	32	31	30
Potassium acetate	23	23	22	22	21	20	-	-