DETAILED DESCRIPTION OF THE INVENTION Coating-forming materials used in autodepositing compositions include resins which are soluble in the composition or which are capable of being dispersed therein in the form of solid particles or in emulsified form.
The use of dispersed resin particles, most preferably supplied in the form of a latex, is preferred.
Examples of resins that can be used are polyethylene, polyacrylics and styrenebutadiene copolymers.
In addition, epoxy resins can be used.
For example, epoxy resins such as, for example, EPON resins, products of Shell Chemical Co.
, can be emulsified with toluene to produce a water-emulsified epoxy resin or ARALDITE resins, products of Ciba-Geigy, can be emulsified to produce a water-emulsified epoxy resin.
Particularly useful latices comprise styrene-butadiene latices sold under the trademark DAREX, by W.
R.
Grace & Co.
The amount of resin utilized can vary over a wide range.
The lower concentration limit is dictated by the amount of resin needed to provide sufficient material to form a coating.
The upper limit is dictated by the amount of material that can be dispersed, dissolved or emulsified in the coating composition.
The composition can comprise about 5 to about 550 g/l.
Preferably, about 100 to about 300 g/l of resin is used, although good results have been achieved also with coating baths containing about 50 g/l of resin.
The preferred autodepositing composition is prepared from hydrofluoric acid and has a pH of about 1.
6 to about 5.
The preferred amount of hydrofluoric acid is about 0.
2 to about 5 g/l of composition.
Although other acids may be used, as known, hydrofluoric acid has the advantage that its anion complexes with ferric iron.
The preferred autodepositing composition is prepared from a soluble ferric salt such as, for example, ferric nitrate or ferric chloride, but most preferably ferric fluoride.
The preferred make-up concentration of ferric iron in the composition is about 0.
5 to about 5 g/l.
It is possilbe also to establish the initial concentration of ferric iron in situ by including in the composition an oxidizing agent, for example, hydrogen peroxide which is capable of oxidizing ferrous iron dissolved from the iron substrate to the ferric form, and in the desired operative amount
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Nonmetallic Processes 
