521-A Hot Spray Stripper

521-A is a high alkaline cleaning system formulated to remove heavy oily soils from ferrous metals in spray application cleaning operations. It has been extensively used in the automotive rebuilding industry. Potent wetting and dispersing agents are combined with a specifically blended alkaline build in order to maximize cleaning and extend cleaning solution life.

  • Efficiently penetrates a wide range of oily soils.
  • Excellent dispersion properties prevent redeposition.
  • Especially well suited for low carbon steel.
  • Gives maximum solution life.
  • Low foaming.

Physical Properties

Appearance: Off-white free-flowing powder
pH @ 1% Solution: 12.45
Odor: Mild
Foaming Action: Very Low
Solubility in water: Excellent
Rinsing Action: Good
Metal Safety: Ferrous Metals
Standard Container: 400 lb. drum
Refer to our Material Safety Data Sheet for additional information.

Usage and Dilution Instructions

For parts washers use 4 to 8 ounces per gallon. Periodic adds of 1 to 2 ounces per gallon will extend cleaning solution life. Solution temperatures should be maintained between 160 and 190 degrees F. For ferrous metals only! Due to high alkalinity, this product may darken, pit or damage non-ferrous metals.

Handling and Storage

This is a highly alkaline product. It contains Sodium Hydroxide. Use good industrial hygiene practices such as wearing chemical safety goggles, rubber gloves, impermeable apron and other appropriate protective clothing to prevent personal contact. Wash thoroughly after handling. In case of skin or eye contact, flush with plenty of water for at least 15 minutes and call a physician. Store in cool dry place in a tightly closed container to reduce caking and rotate stock. When stored as above, shelf life is a minimum of 2 years.


Progress Chemical guarantees its products will perform to your satisfaction when used in accordance to our recommendations. We back this guarantee with over 65 years experience. Our company has been certified to ISO 9001-2015 Quality Standards.