Low Temperature Iron Phosphate Coating for Steel - Freiborne Industries, Inc Low Temperature Iron Phosphate Coating for Steel - Freiborne Industries, Inc

Product Type: Freibond 23

Low temperature low sludging iron phosphate with excellent adhesion and corrosion resistance properties. It may be applied by spray or immersion


FREIBOND 23 is a high quality low temperature iron phosphate coating chemical for steel primarily applied by spray. FREIBOND 23 is designed to impart a uniform coating excellent for bonding paint. It may also be used by immersion but at double the recommended concentration.

Stainless steel, mild steel, and high temperature acid resistant plastics are suitable for processing equipment. Full cone spray nozzles, such as Spraying Systems WhirlJet® nozzles, are normally used in spray applications to ensure uniform application of FREIBOND 23. Spray
pressures should be maintained between 15 and 20 psig. Spray pressure above 20 psig will create inconsistencies and voids in the iron phosphate coating.

To charge the tank, fill to the three-quarter level with water and for each 1000 gallons of working solution, add 360 lbs (36 gallons) of FREIBOND 23 and 4 lbs of NEUTRALIZER 1. Bring the tank up to the working level with water and heat to the operating temperature, from 80oF – 160oF. Once the optimum temperature determined, it should be maintained within 5oF. A processing bath built up according to these recommendations will result in 10 points of Total Acid and a pH adjustment value of 0.4 (pH of 5.0).

An appropriate Freiclean product, followed by a rinse stage, should precede FREIBOND 23 phosphating application. The rinse stage ahead of the FREIBOND 23 can be adjusted with ADDITIVE 37P, at 0.5 to 2.0 points of total acid, to prevent alkaline cleaner drag-in and prepare the substrate for phosphating.

To maintain the bath’s performance it should be regularly tested and adjusted to within operating parameters. Normal processing time with FREIBOND 23 is 60 seconds but processing times often range from 30 to 120 seconds. Processing parameters can vary widely based on individual processes and performance requirements. Typical operating parameters are listed below. Your Freiborne representative will help develop the proper operating parameters for your specific

The pH value can be run on the negative, or free acid, side when numerous welds or laser cutting oxides are present. Consult your Freiborne representative to determine what are the optimum operating parameters for your particular situation.

The FREIBOND 23 treatment is typically followed by a rinse stage and a chrome free final seal rinse such as FREICON 33 or FREICON RSX.

Control is based on Total Acid with pH adjustment.

Total Acid Test:

Pipet a 10 ml sample into a suitable beaker or Erlenmeyer flask and add 4 drops of Indicating Solution 14 (thymolphthalein). Titrate with Testing Solution 11 (0.1N NaOH) to a permanent faint blue endpoint. Addition of 30 lbs (3.0 gallons) of FREIBOND 23 per 1000 gallons will raise the Total Acid by 1 point.

pH Adjustment:

Pipet a 10 ml sample into a suitable beaker or Erlenmeyer flask and add 4 drops of Indicating Solution 2 (Bromcresol green). If the sample turns blue titrate with Testing Solution 20 (0.1NH2SO4) from blue to green. If the sample turns green or yellow, a negative pH adjustment value is indicated. Titrate with Testing Solution 11 to a blue color.

Use ADDITIVE 37P to adjust the pH value down if the Total Acid is within normal operating parameters. Use Freibond 23 to adjust the pH value if the Total Acid is below the normal operating parameters. To lower the pH adjustment by 0.1 points, add 4 lbs (1514 mls) of FREIBOND 23 or 190 mls of Additive 37P per 1000 gallons of solution.

To raise the pH adjustment by 0.1 points, add 7 oz of NEUTRALIZER 1 or 450mls of NEUTRALIZER 35 per 1000 gallons of working solution.

Additional Information

Temp Range



Carbon Steel


Paint Pretreatment

Product Type

Conversion Coatings

Product Line




Ordering Information

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