Rinse Conditioner Bath For Treating A Substrate And Associated Method

Abstract

A rinse conditioner bath that comprises a Jernstedt salt and a soluble iron is disclosed. A method for treating a substrate with the disclosed rinse conditioner bath as well as a zinc phosphate solution is also disclosed.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a rinse conditioner bath comprising a Jernstedt salt and a soluble iron and a method for using the same.

[0003] 2. Background Information

[0004] Phosphate conversion coatings are well known for treating metal surfaces, particularly ferrous, zinc and aluminum metals and their alloys. When applied, these phosphate coatings form a phosphate layer, primarily of zinc and iron phosphate crystals, which provides corrosion resistance and/or enhances the adhesion of subsequently applied coatings.

[0005] Prior to application of the phosphate coating, the metal substrate is typically "conditioned" or "activated" by subjecting the surface of the metal substrate to a diluted aqueous dispersion, sometimes referred to as a rinse conditioner bath or activator, by introducing or immersing the metal substrate into a tank that contains the rinse conditioner bath. "Activation" of the surface of the metal substrate is achieved due to the adsorption of colloidal titanium-phosphate particles, which are present in the rinse conditioner bath, to the metal's surface. These colloidal titanium-phosphate particles, however, have a tendency to agglomerate in the rinse conditioner bath due to dissolved calcium (Ca.sup.2+) and magnesium (Mg.sup.2+) ions (hard water ions) that are typically present in the rinse conditioner bath. The hard water ions are usually introduced into the rinse conditioner bath via the water that is used to create the rinse conditioner bath. Accordingly, to prevent agglomeration of the colloidal titanium-phosphate particles, chelating or sequestering compounds, such as polyphosphates and pyrophosphates, are introduced into the rinse conditioner bath. These chelating/sequestering compounds, however, have been found to degrade with time and cause premature failure of the rinse conditioner bath since the chelating compounds lose their ability to sequester the hard water ions. If softened water is used to create the rinse conditioner bath, these chelants can attack the Jernstedt salt itself and cause the dissolution of the colloidal titanium-phosphate particles thereby preventing the "activation" of the surface of the metal substrate. A rinse conditioner bath having an extended "life span" is therefore desired.

SUMMARY OF THE INVENTION

[0006] The present invention is directed to a rinse conditioner bath comprising a Jernstedt salt and a soluble iron.

[0007] The present invention is also directed to a method for treating a substrate comprising applying a rinse conditioner bath comprising a Jernstedt salt and a soluble iron to at least a portion of the substrate, and phosphatizing at least a portion of the substrate with an aqueous zinc phosphate solution.

[0008] The present invention is further directed to a rinse conditioner concentrate comprising a Jernstedt salt and another salt, wherein the another salt comprises a soluble iron.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:

[0010] FIG. 1 is a top elevation view of a surface of a cold-rolled steel panel under a scanning electron microscope at 1000.times. after the cold-rolled steel panel has been phosphatized with a zinc phosphate solution;

[0011] FIG. 2 is a top elevation view of a surface of another cold-rolled steel panel under a scanning electron microscope at 1000.times. after the cold-rolled steel panel has been phosphatized with a zinc phosphate solution;

[0012] FIG. 3 is a top elevation view of a surface of yet another cold-rolled steel panel under a scanning electron microscope at 1000.times. after the cold-rolled steel panel has been phosphatized with a zinc phosphate solution; and

[0013] FIG. 4 is a top elevation view of a surface of yet another cold-rolled steel panel under a scanning electron microscope at 1000.times. after the cold-rolled steel panel has been phosphatized with a zinc phosphate solution.

DETAILED DESCRIPTION OF THE INVENTION

[0014] As used herein, unless otherwise expressly specified, all numbers such as those expressing values, ranges, amounts or percentages may be read as if prefaced by the word "about", even if the term does not expressly appear. It is also understood that a plural term can encompass its singular counterpart and vice versa.

[0015] When referring to any numerical range of values, such ranges are understood to include each and every number and/or fraction between the stated range minimum and maximum.

[0016] As used herein, the phrase "rinse conditioner bath" will refer to an aqueous solution and/or a colloidal suspension that is applied onto at least a portion of a substrate and/or into which at least a portion of a substrate is immersed in order to promote the formation of a zinc phosphate coating on at least a portion of the substrate that was treated with the rinse conditioner bath. It is, therefore, understood that the substrate is treated with the rinse conditioner bath prior to phosphatizing at least a portion of the treated substrate with a zinc phosphate solution.

[0017] As used herein, the phrase "soluble iron" refers to an iron compound that is soluble in an aqueous medium such as water or a solvent. For example, in one embodiment, the "soluble iron" is ferrous iron (i.e., Fe.sup.2+) that is formed by dissociation of a salt in an aqueous medium. In another embodiment, the "soluble iron" is ferrous iron that is a reaction product of ferric iron (i.e., Fe.sup.3+, Fe(III)) and a reducing agent such as, without limitation, hydrogen peroxide (H.sub.2O.sub.2), which is produced in situ.

[0018] As used herein, the term "vehicle" or variations thereof includes, but is not limited, to civilian, commercial, and military land vehicles such as cars and trucks.

[0019] The present invention is directed to a rinse conditioner bath that is utilized to "activate" or "condition" at least a portion of a substrate prior to phosphatizing at least a portion of a substrate with a zinc phosphate solution. In other words, the rinse conditioner bath promotes the formation of zinc and zinc/iron phosphate crystals on the substrate when at least a portion of the substrate, which was subjected to the rinse conditioner bath, is phosphatized with a zinc phosphate solution. Non-limiting examples of a suitable substrate that can be treated with the rinse conditioner include, but are not limited to, a metal and/or a metal alloy. For example, the metal and/or metal alloy can be aluminum, steel, or zinc. In one embodiment, a steel substrate could include cold rolled steel, electrogalvanized steel, and hot dipped galvanized steel. In one embodiment, the substrate may comprise a portion of a vehicle such as a vehicular body (e.g., without limitation, door, body panel, trunk deck lid, roof panel, hood, and/or roof) and/or a vehicular frame.

[0020] The rinse conditioner bath is comprised of a Jernstedt salt and a soluble iron. The Jernstedt salt typically comprises titanium-phosphate particles such as colloidal titanium-phosphate particles. In one embodiment, the Jernstedt salt is Na.sub.4TiO(PO.sub.4).sub.2. As will be discussed in greater detail below, the addition of soluble iron to the rinse conditioner bath dramatically increases the "life span" of the rinse conditioner bath. As used herein, the phrase "life span" will refer to the total amount of time (e.g., hours, days, weeks, months, etc. . . . ) that the rinse conditioner bath is capable of promoting the formation of zinc phosphate on a substrate. Accordingly, it will be understood that an increase in the "life span" of the rinse conditioner bath will mean that the rinse conditioner bath will not have to be replaced as often, when compared to a rinse conditioner bath that lacks soluble iron, since the rinse conditioner bath disclosed in this invention is capable of promoting the formation of zinc phosphate on the substrate over an extended period of time.

[0021] In one embodiment, the soluble iron is introduced into a rinse conditioner bath via a salt such as, without limitation, ferrous nitrate, ferrous sulfate, ferrous chloride, ferrous gluconate, or combinations thereof. The salt can either be in solid form (e.g. powder/particulate form) or in aqueous form (i.e., dissociated ions in an aqueous medium). In another embodiment, an aqueous rinse conditioner concentrate, which comprises the salt in aqueous form, a liquid thickener, chelating compound(s), and a Jernstedt salt, is added to an aqueous solution, such as water, to form the disclosed rinse conditioner bath. Suitable liquid thickeners that can be used in the aqueous rinse conditioner concentrate would include, but are not limited to, hydroxyl methyl cellulose, xanthan gum, and polycarboxylic acid, and combinations thereof. In yet another embodiment, the rinse conditioner is formed by the introduction of a powder concentrate, which comprises a chelating compound, into an aqueous solution, such as water, to form a precursor to the rinse conditioner bath. The salt, which is in aqueous and/or solid form, is then added to the precursor to the rinse conditioner bath in order to form the disclosed rinse conditioner bath. In yet another embodiment, the salt, which is in solid form, is added to a powder concentrate before the powder concentrate is added to the aqueous solution to form the disclosed rinse conditioner. Hereinafter, the aqueous rinse conditioner concentrate as well as the powder concentrate will be collectively referred to as a rinse conditioner concentrate. It will be understood that, as used herein, the rinse conditioner concentrate is typically used to make the rinse conditioner bath that is applied onto a substrate prior to the substrate being subjected to a phosphatizing step using a zinc phosphate solution.

[0022] In the various embodiments described above, the aqueous solution to which the rinse conditioner concentrate is added could be an aqueous solution which has low hardness. As used herein, the phrase "low hardness" refers to an aqueous solution containing .ltoreq.25 ppm of calcium carbonate and/or magnesium. For example, the aqueous solution could be deionized water, distilled water, reverse osmosis water, or combinations thereof.

[0023] The soluble iron can be present in the rinse conditioner bath in an amount ranging from 5 to 1000 ppm based on the total weight of the rinse conditioner bath. In another embodiment, the soluble iron can be present in the rinse conditioner bath in an amount ranging from 20 to 30 ppm based on the total weight of the rinse conditioner bath. As demonstrated in the examples below, addition of soluble iron into the rinse conditioner bath can increase the "life span" of the rinse conditioner bath. Though not wishing to be bound by any particular theory, it is believed that the addition of soluble iron into the rinse conditioner bath extends the "life span" of the rinse conditioner bath because the chelating/sequestering compounds, which are typically added to the rinse conditioner bath, have a preference to attack the soluble iron as opposed to attacking and causing the dissolution of the Jernstedt salt. Because the Jernstedt salt is not dissolved by the chelating/sequestering compounds, the Jernstedt salt would continue to promote the formation of zinc and iron phosphate crystals on the substrate that is being treated.

[0024] In one embodiment, the rinse conditioner bath to which the soluble iron is added comprises sodium phosphate, potassium phosphate, and titanium wherein the titanium is present as a complex salt with either or both sodium phosphate and the potassium phosphate.

[0025] Suitable sodium phosphates useful in the rinse conditioner bath described in the preceding paragraph include, without limitation, mono- di- or tri-sodium phosphate, pentasodium triphosphate (also known as sodium tripolyphosphate), tetrasodium diphosphate, (tetrasodium pyrophosphate) disodium orthophosphate, pentasodium triphosphate, or combinations thereof.

[0026] Suitable potassium phosphates useful in the rinse conditioner bath include, without limitation, mono-, di- or tri-potassium phosphate, pentapotassium triphosphate (also known as potassium tripolyphosphate), dipotassium orthophosphate, tetrapotassium pyrophosphate or combinations thereof.

[0027] A variety of titanium (IV) compounds or salts may be used as the source of titanium in the rinse conditioner bath as long as the anion of the salt does not interfere with the subsequent zinc phosphate pretreatment. For example, titanium halides, titanium oxides (e.g., titanium dioxide), titanium sulfates and titanium oxalates may be used. While the selection of the titanium source is not limited, titanium halides, specifically potassium titanium fluoride is most suitable.

[0028] The rinse conditioner bath may further comprise additional optional components such as, without limitation, diphosphonic acids, alkali metal carbonates or hydroxides and/or thickening agents (e.g., xanthans, polysaccharides and polycarboxylates).

[0029] The rinse conditioner bath described above can be prepared by introducing a rinse conditioner concentrate to an aqueous medium such as water. In one embodiment, the rinse conditioner concentrate is prepared by mixing in an aqueous medium a sodium phosphate with a titanium compound and heating the mixture to form a paste-like pre-mix. For example, the paste-like premix can be made by adding pentasodium triphosphate to water, which is preheated to a temperature ranging from 65.degree. C. to 95.degree. C., in order to form a slurry. A titanium compound is then added to the slurry and the slurry is agitated. After thorough mixing, disodium orthophosphate is added to the slurry and the slurry mixed thoroughly for about 5 to 15 minutes. After the disodium orthophosphate is mixed with the slurry, a paste-like pre-mix containing the titanium phosphate complex salt is produced.

[0030] The paste-like pre-mix is then combined with potassium phosphate and other ingredients, such as a liquid thickener, to form the conditioner concentrate. The potassium phosphate may be one or a combination of the potassium phosphates described above. It is generally suitable to use dipotassium orthophosphate or a combination of dipotassium orthophosphate and pentapotassium triphosphate. tetrapotassium pyrophosphate is additionally suitable when activating aluminum substrates. It is noted that in other embodiment, the paste-like pre-mix may be added to the potassium phosphate hot or after a cooling period. In this particular embodiment, the rinse conditioner concentrate is a concentrated aqueous dispersion of a titanium containing phosphate composition.

[0031] Typically, the sodium phosphate is present in amounts of from 10% to 30% by weight, the potassium phosphate is present in amounts of from 20% to 40% by weight, the titanium is present in amounts of from 0.05% to 2.5% by weight, and water is present in amounts of from 30% to 60% by weight, the percentage by weight based on the total weight of the ingredients used in making the rinse conditioner concentrate. Usually, the sodium phosphate is disodium orthophosphate in combination with pentasodium triphosphate, and the disodium orthophosphate is present in amounts of from 10% to 25% by weight and the pentasodium triphosphate is present in amounts of from 1% to 10% by weight, the percentage by weight being based on total weight of ingredients used in making the rinse conditioner concentrate. The potassium phosphate is preferably dipotassium orthophosphate in combination with pentapotassium triphosphate, and the dipotassium orthophosphate is typically present in amounts of from 5% to 20% by weight and the pentapotassium triphosphate is present in amounts of from 10% to 25% by weight, the percentage by weight being based on total weight of ingredients used in making the rinse conditioner concentrate. In the embodiment where tetrapotassium pyrophosphate is used, the tetrapotassium pyrophosphate is present in amounts of up to 5% by weight based on total weight of the ingredients used in the making of the rinse conditioner concentrate.

[0032] In accordance with a method of the present invention, a substrate is treated by (a) applying a rinse conditioner bath comprising a Jernstedt salt and a soluble iron to a least a portion of the substrate, and (b) phosphatizing at least a portion the substrate with an aqueous zinc phosphate solution. In one embodiment, the rinse conditioner bath can be applied to the substrate by spray, roll-coating or immersion techniques. The rinse conditioner bath is typically applied onto the substrate at a temperature ranging from 20.degree. C. to 50.degree. C. for any suitable period of time. After the surface of the substrate has been "activated", the surface of the substrate is subjected to a phosphate pretreatment such as a zinc phosphate pretreatment. The phosphatizing step can be performed by spray application or immersion of the activated substrate in an acidic phosphate bath which contains zinc and other divalent metals known in the art at a temperature ranging from 35.degree. C. to 75.degree. C. for 1 to 3 minutes. After phosphatizing, the substrate is optionally post-rinsed with a chromium or non-chromium containing solution, rinsed with water and optionally dried. Paint is then typically applied, such as, by electrodeposition or by conventional spray or roll coating techniques.

[0033] The present invention is also directed to a conditioner stage such as those used in an automotive manufacturing facility. In one embodiment, the conditioner stage comprises an immersion tank which contains the rinse conditioner bath that is disclosed in this invention. In one embodiment, the rinse conditioner bath is contained within the immersion tank at a temperature ranging from 20.degree. C. to 50.degree. C. A portion of the substrate is subjected to the rinse conditioner bath by immersing the substrate in the rinse conditioner bath for any suitable period of time. After being immersed in the rinse conditioner bath, a portion of the "activated" substrate is then subjected to a phosphatizing step by applying a zinc phosphate solution to the "activated" substrate. It should be noted, however, that prior to the application of the phosphate solution to the "activated" substrate, additional rinse conditioner bath can be sprayed onto a portion of the "activated" substrate via a spraying nozzle as the "activated" substrate is removed from the immersion tank. For example, the spraying nozzle could be an "exit halo" which is positioned downstream from the immersion tank. After the "activated" substrate exits the immersion tank and/or after additional rinse conditioner is applied onto the "activated" substrate, the "activated" substrate is phosphatized by applying a zinc phosphate solution to the "activated" substrate using techniques that are known in the art such as a spray and/or an immersion technique.

[0034] In another embodiment, the conditioner stage comprises a number of spraying nozzles that are used to apply the rinse conditioner bath onto a least a portion of a substrate. Disposed beneath the spraying nozzles is a spray tank which is adapted to collect the rinse conditioner bath that exits the spraying nozzles and/or any excess rinse conditioner bath that drips off the surface of the "activated" substrate. The spray tank is connected to the spraying nozzles in a manner that allows the spraying nozzles to utilize the rinse conditioner bath that is collected in the spray tank thereby recycling the rinse conditioner bath. After the rinse conditioner bath is applied onto at least a portion of the substrate, the "activated" substrate is then phosphatized as described in the preceding paragraph.

[0035] Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.

EXAMPLES

Example 1

[0036] Two 4 liter rinse conditioner baths, Baths A and B, were prepared by adding 1.0 gram of a commercially available Liquid Rinse Conditioner (available from PPG Industries, Inc. of Pittsburgh, Pa.) per 1 liter of deionized water. No ferrous iron (Fe(II)) was added to Bath A while ferrous iron was added to Bath B at a concentration of 20 ppm (0.4 g FeSo.sub.4.7H.sub.20). It will be understood that Bath A is the control.

[0037] Two cold-rolled steel test panels (available from ACT Laboratories, of Hillsdale, Mich.), Steel Panels D and E, were processed through an alkaline cleaning process and rinsed with tap water. After being rinsed with tap water, Steel Panel D was immersed in Bath A for 30 seconds at ambient temperature. Steel Panel D was then removed from Bath A and phosphatized with a zinc phosphate solution, CHEMFOS 700AL (available from PPG Industries, Inc. of Pittsburgh, Pa.), which was maintained at a Free Acid (FA) range of 0.8 to 0.9, a Total Acid (TA) range of 15 to 16.5, and a temperature of 52.degree. C. (+/-1.degree. C.). After being rinsed with tap water, Steel Panel E was immersed in Bath B for 30 seconds at ambient temperature. Steel Panel E was then removed from Bath B and phosphatized with a zinc phosphate solution, CHEMFOS 700AL, which was maintained at a Free Acid (FA) range of 0.8 to 0.9, a Total Acid (TA) range of 15 to 16.5, and a temperature of 52.degree. C. (+/-1.degree. C.).

[0038] Referring to FIG. 1, this is a top elevation view of the surface 2 of Steel Panel D after Steel Panel D was phosphatized with CHEMFOS 700AL. The extensive number of nodular crystalline structures 4 seen in FIG. 1 is the zinc phosphate coating 6 that was formed over essentially the entire surface 2 of Steel Panel D during the phosphatizing process. The formation of the substantially uniform zinc phosphate coating on the surface of Steel Panel D was promoted by the rinse conditioner bath of Bath A. Accordingly, the rinse conditioner bath of Bath A was active. As used hereinafter in connection with the phrase "rinse conditioner bath", the term "active" will refer to a rinse conditioner bath's ability to promote the formation a zinc phosphate coating on a substrate.

[0039] Referring to FIG. 2, this is a top elevation view of the surface 8 of Steel Panel E after Steel Panel E was phosphatized with CHEMFOS 700AL. Similar to the zinc phosphate coating that is seen in FIG. 1, the extensive number of nodular crystalline structures 10 seen in this figure is a substantially uniform zinc phosphate coating 12 that was formed over essentially the entire surface 8 of Steel Panel E during the phosphatizing process. The formation of the extensive zinc phosphate coating 12 on the surface 8 of Steel Panel E was promoted by the rinse conditioner bath of Bath B. In other words, the rinse conditioner in Bath B, like Bath A, was active.

Example 2

[0040] In order to determine the life span of the rinse conditioner in Baths A and B, two cold-rolled steel test panels, Steel Panels Y and Z, were immersed in Baths A and B after a 24 hour period from when Steel Panels D and E were immersed in Baths A and B. Similar to Steel Panels D and E, Steel Panels Y and Z were processed through an alkaline cleaning process and rinsed with tap water. After being rinsed with tap water, Steel Panel Y was immersed in Bath A for 30 seconds at ambient temperature. Steel Panel Y was then removed from Bath A and phosphatized with a zinc phosphate solution, CHEMFOS 700AL, which was maintained at a Free Acid (FA) range of 0.8 to 0.9, a Total Acid (TA) range of 15 to 16.5, and a temperature of 52.degree. C. (+/-1.degree. C.). After being rinsed with tap water, Steel Panel Z was immersed in Bath B for 30 seconds at ambient temperature. Steel Panel Z was then removed from Bath B and phosphatized with a zinc phosphate solution, CHEMFOS 700AL, which was maintained at a Free Acid (FA) range of 0.8 to 0.9, a Total Acid (TA) range of 15 to 16.5, and a temperature of 52.degree. C. (+/-1.degree. C.).

[0041] Referring to FIG. 3, this is a top elevation view of the surface 14 of Steel Panel Y after Steel Panel Y was phosphatized with CHEMFOS 700AL. Unlike, FIGS. 1 and 2, however, the surface 14 of Steel Panel Y lacked the extensive number of crystalline structures 4, 10 that were observed on the surface of Steel Panels D and E, respectively. Rather, a few scattered crystalline structures 16 were observed on the surface 14 of Steel Panel Y. Moreover, the surface 14 of Steel Panel Y was actually visible when viewed under the scanning electron microscope. It will be understood that the rinse conditioner bath of Bath A, after 24 hours, was unable to promote the formation of a substantially uniform zinc phosphate coating on the surface of Steel Panel Y. In other words, the life span of the rinse conditioner bath of Bath A was essentially 24 hours since the rinse conditioner bath was unable to promote the formation of a substantially uniform zinc phosphate coating on the surface of Steel Panel Y.

[0042] Referring to FIG. 4, this is a top elevation view of the surface 18 of Steel Panel Z after Steel Panel Z was phosphatized with CHEMFOS 700AL. Unlike Steel Panel Y, Steel Panel Z contained an extensive number of nodular crystalline structures similar to those observed in Steel Panels D and E. The formation of the nodular crystalline structures 20 (i.e., the zinc phosphate coating) on the surface 18 of Steel Panel Z was promoted by the rinse conditioner bath of Bath B. Unlike the rinse conditioner bath of Bath A, however, the rinse conditioner bath of Bath B was active, even after 24 hours, due to the addition of ferrous iron to the rinse conditioner bath of Bath B.

Claims

1. A rinse conditioner bath comprising a Jernstedt salt and a soluble iron.

2. The rinse conditioner bath according to claim 1, wherein said soluble iron is iron (II).

3. The rinse conditioner bath according to claim 1, wherein said iron comprises 5-1000 ppm of the total weight of said rinse conditioner bath.

4. The rinse conditioner bath according to claim 3, wherein said iron comprises 20-30 ppm of the total weight of said rinse conditioner bath.

5. The rinse conditioner bath according to claim 1, wherein said soluble iron is introduced into said rinse conditioner bath via a salt.

6. The rinse conditioner bath according to claim 1, wherein said salt is in solid or aqueous form.

7. The rinse conditioner bath according to claim 5, wherein said salt comprises ferrous nitrate, ferrous sulfate, ferrous chloride, ferrous gluconate, or combinations thereof.

8. The rinse conditioner bath according to claim 1, wherein said rinse conditioner bath is prepared from a mixture of a rinse conditioner concentrate and an aqueous medium.

9. The rinse conditioner bath according to claim 8, wherein said rinse conditioner concentrate is an aqueous rinse conditioner concentrate containing said soluble iron.

10. The rinse conditioner bath according to claim 8, wherein said rinse conditioner concentrate is a powder concentrate and wherein said powder concentrate contains said soluble iron.

11. The rinse conditioner bath according to claim 1, wherein said rinse conditioner bath further comprises chelating compounds.

12. The rinse conditioner bath according to claim 1, wherein said soluble iron is a reaction product of iron (III) and a reducing agent.

13. A method for treating a substrate comprising (a) applying a rinse conditioner bath comprising a Jernstedt salt and a soluble iron to at least a portion of said substrate, and (b) phosphatizing at least a portion of said portion of said substrate with a zinc phosphate solution.

14. The method according to claim 13, wherein said soluble iron is iron (II).

15. The method according to claim 13, wherein said iron comprises 5-1000 ppm of the total weight of said rinse conditioner bath.

16. The method according to claim 15, wherein said iron comprises 20-30 ppm of the total weight of said rinse conditioner bath.

17. The method according to claim 13, further comprising introducing said soluble iron into said rinse conditioner bath via a salt.

18. The method according to claim 17, wherein said salt comprises ferrous nitrate, ferrous sulfate, ferrous chloride, ferrous gluconate, or combinations thereof.

19. The method according to claim 17, wherein said salt is in solid form.

20. The method according to claim 17, wherein said salt is in an aqueous medium.

21. The method according to claim 13, wherein said rinse conditioner bath is prepared by (i) providing an aqueous solution and (ii) introducing an aqueous rinse conditioner concentrate comprising said Jernstedt salt and said soluble iron into said aqueous solution.

22. The method according to claim 21, wherein said aqueous rinse conditioner concentrate comprises a liquid thickener, a chelating compound, and said Jernstedt salt.

23. The method according to claim 13, wherein said rinse conditioner bath is prepared by (i) providing an aqueous solution, (ii) introducing a powder concentrate comprising said Jernstedt salt into said aqueous solution, and (iii) introducing said soluble iron into said aqueous solution.

24. The method according to claim 13, wherein said rinse conditioner bath is prepared by (i) providing an aqueous solution, (ii) forming a powdered mixture comprising said soluble iron and said Jernstedt salt, and (iii) introducing said powdered mixture into said aqueous solution.

25. The method according to claim 13, wherein said rinse conditioner bath further comprises chelating compounds.

26. The method according to claim 13, wherein said soluble iron is a reaction product of iron (III) and a reducing agent.

27. A rinse conditioner concentrate comprising a Jernstedt salt and another salt, wherein said another salt comprises a soluble iron.

28. The rinse conditioner concentrate according to claim 28, wherein said another salt is in aqueous or solid form.