CAUSTIC SODA 25%
Liquid Caustic Soda

An aqueous solution of sodium hydroxide containing 25% by weight anhydrous sodium hydroxide, NaOH; the chemical name and formula of caustic soda. Caustic soda 25% HAS A FREEZING POINT OF 0°F; this permits shipping and storage under normal conditions whereas caustic soda 50% freezes at 58°F.

Caustic Soda 25%, used with Cardite #170, is recommended for many cleaning applications; see green data page on Cardite #170. For aluminum etching, see green data page on Cardite #1211.

Properties & DOT Class
Caustic Soda 25%

State @ 70°F	liquid	Freeze Point	0°F
Turbidity slight	Freeze-Thaw	Recovery	complete
Odor	none	Viscosity @ 70°F	6.4 cp
Specific Gravity	1.278	Fire Hazard	noncombustible
Solution Weight, #/G	10.66	DOT-Hazard Label	corrosive
Caustic Soda, #/G	2.66	Solubility, in water	miscible
pH, as is	14	Solubility, in hydrocarbons	negligible

Properties of Caustic Soda Solutions
based on international critical tables volume 3 page 79

NaOH	Freeze Point		NaOH	Solution Weight	Specific Gravity
by weight	°F	°C	#/gal	#/gal	60/60°F
1%	30	-1	0.08	8.44	1.012
5%	25	-4	0.44	8.81	1.056
10%	18	-8	0.93	9.27	1.112
15%	0	-18	1.46	9.73	1.167
20%	-12	-24	2.04	10.20	1.223
25%	0	-18	2.66	10.66	1.278
30%	36	2	3.33	11.11	1.332
40%	60	16	4.78	11.96	1.434
50%	58	14	6.38	12.76	1.530
60%	120	49	7.94	13.24	1.590
70%	147	64	9.85	14.08	1.690

Personal Precautions

DANGER! Causes IMMEDIATE damage when it contacts the body. For eye contact, start washing with water in less than 10 seconds to prevent permanent injury. For skin contact, start washing with water immediately to prevent slow-healing skin injury. Users should ALWAYS wear chemical workers' safety goggles and a wide-brim hat. Depending on probability of exposure additional protection may be needed, including: full face shield, neoprene or rubber gloves and apron, rubber boots, respirator if air-borne particles are possible, complete suit of neoprene, rubber, or plastic coated fabric, buttoned at neck, pants outside boots, sleeves over gloves.

FIRST AID: EYES: Wash IMMEDIATELY with water at low pressure and continue washing for AT LEAST 15 minutes, holding eyelids open. Call physician at once; continue washing until told to stop by a physician. Do NOT attempt to neutralize chemically.

FIRST AID: SKIN: For small areas, as hands, wash thoroughly with water for at least 15 minutes. Remove clothing in shower. Do not remove goggles at first since caustic could run into eyes. Wash thoroughly, then close eyes and remove goggles, then continue washing. Wash clothing before reuse. Discard shoes.

FIRST AID: INGESTION: If swallowed, immediately drink large quantities of water, or preferably milk, and call aphysician. Do NOT induce vomiting.