Immersion Zinc Phosphate Coating - Freiborne Industries, Inc Immersion Zinc Phosphate Coating - Freiborne Industries, Inc

Product Type: Formcoat 1

FORMCOAT 1 is an immersion zinc phosphate coating process. FORMCOAT 1 provides proven time testedperformance. FORMCOAT 1 is used primarily to facilitate cold forming when used in conjunction with aFORMLUBE lubricant, or wire drawing when used in conjunction with a FORMATE series drawing compound.


Additional Information

Temp Range



Carbon Steel


Drawing, Extrusion

Product Type

Conversion Coatings

Product Line




  • The process tank should be constructed from stainless steel or an acid and oxidizer resistantcomposite material that will withstand the temperature ranges required. Use of mild steel will resultin shortened equipment life due to chemical attack.
  • Heat transfer surfaces should be constructed of 316 stainless steel, or an acid and oxidizerresistant high temperature composite, if steam or heat transfer fluid type heat exchangers areused.
  • Piping and pumps may be constructed of stainless steel, mild steel, or an appropriate compositematerial. Use of mild steel will result in shortened equipment life.

Fill the tank to the three quarter level with water and add 81 gallons (1036 LBS) of FORMCOAT 1A chemicalfor each 1,000 gallons of working solution required. With water bring the tank to the operational level andheat to the required temperature, typically 180oF. Once the optimum temperature is determined, it should bemaintained within ±5oF. A processing bath built up according to these recommendations will result in 25points of Total Acid, or what is referred to as a 25 point bath. Cleaned steel is placed in this solution for 3 to10 minutes to produce a uniform coating.

To calculate the amount of FORMCOAT 1A necessary to build up a bath use the following equation:

(Working Volume) x (Total Acid Points Desired) x (0.003247) = Volume of FORMCOAT 1A Required

Example: To build up a 5000 gallon working volume bath at 30 points of total acid

(5000 gal) x (30 points) x (0.003247) = 487 gallons of FORMCOAT 1A required

Just before any work is processed, add 10 oz. (220 mls.) of Freidox 2 or 20 oz. (500 mls. of a20% solution of Freidox 1) per 1,000 gallons and mix.

  • The treatment process for FORMCOAT 1 is generally as follows:

1. Cleaning with a FREICLEAN series cleaner
2. Hot water rinse
3. Pickle
4. Cold water spray rinse
5. Cold water rinse
6. Hot water preheat
8. Cold water rinse
9. Hot NEUTRALIZER rinse
10. FORMLUBE soap or polymer series lubricant

To maintain the bath’s performance, it should be regularly tested and adjusted to within operatingparameters. Normal processing time with FORMCOAT 1 is 3 to 10 minutes. Processing parameterscan vary widely based on individual processes and performance requirements. Typical operatingparameters are listed below. Your Freiborne representative will help develop the proper operatingparameters for your specific needs.

Immersion Application
Control Parameter Minimum Maximum
Temperature 170°F 195°F
Total Acid 20.0 40.0
TA/FA 5.5 7.5
Treatment Time 3 Minutes 10 Minutes

Insoluble phosphate sludge will be generated as a natural byproduct of the FORMCOAT 1 reaction withthe steel. This sludge must be periodically removed to prevent it from depositing on the surface of thesteel being coated, as it is abrasive in nature and therefore very detrimental to forming operation.

Maintaining the temperature of the rinse prior to FORMCOAT 1 as close to the temperature of theFORMCOAT 1 as possible will reduce both chemical consumption and sludge generation.

If the FORMCOAT 1 phosphating solution is continually heated when not in used excess free acid will begenerated resulting in a low TA/FA ratio. To avoid this situation the tank temperature should be loweredduring long periods of inactivity.

Testing and control of a FORMCOAT 1 bath is based on Total Acid and Total Acid/Free Acid ratio (TA/FARatio) according to the following table.

Total Acid: Using a 5ml volumetric pipette, transfer a 5ml sample of the FORMCOAT 1 into a clean 250ml Erlenmeyer flask (adding up to 50ml of DI water to the flask may aid in viewing theendpoint). Add 5 drops of Indicating Solution #3 (Phenolphthalein) and titrate with Testing Solution #11 (0.1 N NaOH) to a slight pink endpoint. Record the buret reading asthe Total Acid.
Free Acid: Using a 5ml volumetric pipette, transfer a 5ml sample of the FORMCOAT 1 into a clean250ml Erlenmeyer flask (adding up to 50ml of DI water to the flask may aid in viewing the endpoint). Add 5-10 drops of Indicating Solution #11 (Bromophenol Blue) and titrate with Testing Solution #11 (0.1 N NaOH) to a blue-green endpoint (absence of yellow).  Recordthe buret reading as the Free Acid.

TA/FA Ratio: Divide the total acid reading by the free acid reading to obtain the TA/FA ratio

Test Parameter Sample Size   Testing Solution Control Range
Total Acid 5 ml 5 drops IS #3 (Phenolphtalien)
Clear to permanent faint pink
TS #11
(0.1N NaOH)
Free Acid 5 ml 5 drops IS #11 (Bromophenol Blue)
Yellow to blue-green
TS #11
(0.1N NaOH)
TA/FA Ratio 5.5-7.5

TA/FA Ratio: For a fresh bath this is normally in the 5.5-7.5 range. If this ratio drops below 5.8, discontinue using FORMCOAT 1B replenishing chemical and use FORMCOAT 1A until the ratio is above 6.0.If, even with proper testing and control, your TA/FA ratio is routinely out contact your Freibornerepresentative about using a modified replenisher.

An addition of 27 lbs. (2.0 gallons) of FORMCOAT 1B per 1000 gallons of solution will raise the Total Acid1.0 point.

An addition of 41 lbs. (3.2 gallons) of FORMCOAT 1A per 1000 gallons of solution will raise the Total Acidby 1.0 point.

FREIDOX TESTING: (recommended after bath is idle for more than 4 hours or if the bath exhibits an abnormal color)Dip a strip of Indicator Paper 17 into the working solution. If it turns pink FREIDOX must be added, asabove, until a fresh piece of paper does not change color. If it should turn pink the bath is on the “ironside” and further work should not be processed until sufficient “Freidox” is added to kick out the ironfrom the solution. This can be done using the same quantities, in increments, as with a new bath.

Ordering Information

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