A testing method for levelling power of plating baths is proposed. The conventional method has a defect not to pay little consideration for the depth of surface scratches. The proposed method is to compare levelling power-scratch depth curves and to get more reproducible result.
At the same time a more practical numerical method for representing levelling power is suggested and discussed.

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Using the experimental method as in the previous paper, effects of plating conditions on the levelling power of copper cyanide plating bath were investigated.
As a result obtained it is concluded that the levelling power of copper cyanide bath depends largely upon cathodic concentration polarization.
Some other important findings will be explained in detail and discussed in this paper.

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Only sodium hypophosphite is now practically used as reducing agent, one of the components of electroless nickel plating solution.
Some reducing agents selected from the consideration of chemical equilibrium in nickel reducing reaction were tested for the electroless nickel plating solutions.
As a result, formic acid was found to be promising other than sodium hypophosphite.

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In order to study the relationship between rust preventive additives and their bases, mainly of corrosion preventives of solvent cut back type, four sorts of corrosion tests were carried out.
Rust preventive properties were so remarkably improved as the bases were shifted from lubricating oil alone to petrolatum blended with lubricating oil and solvent, then further to petrolatum mixed with solvent that testing terms had to be put off according to the alternation of the bases mentioned above.
When rust preventive additives were used to each of the bases, sorbitan mono oleates and barium sulphonates were superior to remaining three additives in the salt spray test, and oleyl sarcosine showed good results in the humidity cabinet test with sulphure dioxide employed. But in the accelerated weathering test and the outdoor exposure test they did not yield good results. In addition, especially when lubricating oil alone was used as a base, corrosion occured so easily that the effects of additives used couldnot be evaluated well.
On the other hand, by the use of a rust preventive oil of P-1 type, in which, different from three kinds of bases already mentioned, asphalt mixed with solvent is used as a base, corrosion was unlikely to occur in the accelerated weathering test as well as in the outdoor exposure test even though the additives were not used.

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It is generally understood that corrosion preventives of solvent cut back type stand severer conditions of corrosion than those of tubricating oil type, which is said to be mainly due to the composition of the bases employed therein.
In order to study the relationship between viscosity and film thickness of rust preventive oils, the bases in which petrolatum is chiefly used were taken up and their kinetic viscosities computed from their pippete viscosities were measured and then the relationship of kinetic viscosity and film thickness of the bases were studied.
The film thickness of lubricating oils is less than 10 microns even though their viscosities are high, and the viscosity of a rust preventive oil of asphalt base, i. e., of P-1 type, becomes pretty high when suitable film thickness, e. g., more or less 50 microns, is required.
On the contrary, the rust preventive oil of P-2 or P-3 type, in which petrolatum, lubricating oil and solvent are blended together as a base, has advantages that the viscosity of the product can be kept low and that the film thickness can be easily adjusted according to the quantity of the solvent blended therein.

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