High Quality Iron Phosphate Process - Freiborne Industries, Inc High Quality Iron Phosphate Process - Freiborne Industries, Inc

Product Type: Freibond 10

This is our preferred and highest quality process. It is simple to control, robust in its tolerance, and shows excellent adhesion and corrosion resistance under paint. It may be applied by spray or immersion.


FREIBOND 10 is a high quality iron phosphate coating chemical for steel primarily applied by spray. FREIBOND 10 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. Utilizing 300 series stainless steel equipment will significantly increase the service life of the equipment. Full cone spray nozzles, such as Spraying Systems WhirlJet® nozzles, are normally used in spray applications to ensure uniform application of FREIBOND 10. Spray pressures should be maintained at 15 psig for optimum coating. Spray pressure above 20 psig will create inconsistencies and voids in the iron phosphate coating.

Utilization of deionized or reverse osmosis water in the system will reduce both chemical
consumption and sludge generation. Application equipment should be cleaned or a regular maintenance cycle with PICKLE 2 to remove sludge and scale deposits that may interfere with application and subsequent performance.

To charge the tank, fill to the three-quarter level with water and for each 1000 gallons of working solution, add 380 lbs (36 gallons) of FREIBOND 10 and 9 lbs of NEUTRALIZER 1 for spray applications or 760 lbs (72 gallons) of FREIBOND 10 and 18 lbs of  EUTRALIZER 1 for immersion applications. Bring the tank up to the working level with water and heat to the operating temperature (spray = 150oF – 170oF, immersion = 175oF – 185oF). Once the optimum temperature has been determined, it should be maintained within ±5oF. A processing bath built up according to these recommendations will result in 10 points of Total Acid for a spray application or 20 points of Total Acid for immersion processes and a pH adjustment value of 0.4 (pH of 5.0).

The typical process sequence for Freibond D37 application consists of the following steps:

1. FREICLEAN treatment
2. Warm Water Rinse
3. FREIBOND 10 treatment (one or two stages)
4. Water Rinse
5. FREICON post treatment seal
6. Deionized water rinse
7. Drying

An appropriate Freiclean product, followed by a rinse stage, should precede FREIBOND 10 phosphating application. The rinse stage ahead of the FREIBOND 10 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 10 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 needs.

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 10 treatment is typically followed by a rinse stage and a chrome free final seal rinse such as 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 10 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 10 to adjust the pH value down if the Total Acid is below the normal operating parameters. To lower the pH adjustment by 0.1 points, add 3 lbs (1017 mls) of FREIBOND 10 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 per 1000 gallons of working solution.

Chemicals Typically Required:


Additional Information

Temp Range



Carbon Steel


Paint Pretreatment

Product Type

Conversion Coatings

Product Line



Spray or Immersion

Ordering Information

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