High Weight Zinc Phosphate Coating - Freiborne Industries, Inc High Weight Zinc Phosphate Coating - Freiborne Industries, Inc

Product Type: Formcoat 13

Unique formulation that provides higher zinc phosphate coating weights (>1000mg/ft2) while still operating on the nitrite side.


FORMCOAT 13 is an immersion zinc phosphate coating bath for the cold forming industry. Characteristics of FORMCOAT 13 in operation are low sludging and higher coating weights than conventional nitrite side bath. FORMCOAT 13 is used primarily to facilitate cold forming when used in conjunction with a FORMLUBE lubricant, or wire drawing when used in conjunction with a FORMATE series drawing compound.

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

To charge the tank, fill to three-quarter level with water and add approximately 60 gallons of FORMCOAT 13A (or 800 lbs) for each 1000 gals. of required working volume. Bring the solution up to the working level with water and heat, with mixing, to the operating temperature range of 165-185°F. Just before processing, add 6 oz. (220 mLs) of FREIDOX 2 per 1000 gallons and mix.

Treatment times range from 5 to 15 minutes.

Maintain the rinse ahead of the FORMCOAT 13 at or above the temperature of the FORMCOAT 13 bath. A low temperature rinse ahead of the FORMCOAT 13 bath will result in excessive sludge generation.

The treatment process for FORMCOAT 13 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 operating parameters. Normal processing time with FORMCOAT 13 is 3 to 10 minutes. Processing parameters can vary widely based on individual processes and performance requirements. Typical operating parameters are listed below. Your Freiborne epresentative will help develop the proper operating parameters for your specific needs.

Insoluble phosphate sludge will be generated as a natural byproduct of the FORMCOAT 13 reaction with the steel. This sludge must be periodically removed to prevent it from depositing on the surface of the steel being coated, as it is abrasive in nature and therefore very detrimental to forming operation. The frequency of sludge removal will depend on the processing parameters and the type and surface area of steel being processed.

Maintaining the temperature of the rinse prior to FORMCOAT 13 as close to the temperature of the FORMCOAT 13 as possible will reduce both chemical consumption and sludge generation.

If the FORMCOAT 13 phosphating solution is continually heated when not in used excess free acid will be generated resulting in a low TA/FA ratio. To avoid this situation the tank temperature should be lowered during long periods of inactivity, preferably to 160°CF or lower.

Testing and control of a FORMCOAT 13 bath is based on Total Acid and Total Acid/Free Acid ratio (TA/FA Ratio) according to the following table.

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 13B replenishing chemical and use FORMCOAT 13A until the ratio is above 6.0. If, even with proper testing and control, your TA/FA ratio is routinely out of the recommended control
parameters contact your Freiborne representative about using a modified replenisher.

Additions of 30 lbs. (2.4 gallons) of FORMCOAT 13D per 1000 gallons will increase the Total Acid by 1
point. If the TA/FA ratio drops below (5.0) or goes above (7.0) consult your Freiborne representative. Only under conditions of mechanical loss should FORMCOAT 13A be used. Use 40 lbs. (3.2 gallons) of FORMCOAT 13A per 1000 gallons to raise the Total Acid by 1 point.

Depending on the specific operation – including the load factor in the process tank, the quantity of production, the level of high carbon verses low carbon stock processed – variations in the above replenishing schedule may be required for optimum performance. The final recommendations are best left
to Freiborne service personnel during initial operation.

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

Additional Information

Temp Range



Carbon Steel


Drawing, Extrusion

Product Type

Conversion Coatings

Product Line




Ordering Information

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