In the barrel finishing, the different kinds of compounds resulted in the different volumes of roughness and polishing removal. Using the sodium carbonate of less polishing power, the volume of roughness removal decreased, and the sodium oleate of polishing power, the volume of roughness removal was twice as much as that of sodium carbonate and the polishing removal remarkably increased. By addition of the abrasive, the surface became uneven and the volume of roughness and polishing removal increased. The volume increased with an increase of the number of revolution of barrel. The use of the big media greatly increased the volume of roughness removal. When 2% sodium stearate was used as the brightness compounds, even the slight unevenness was easily removed.

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Main processing factors in hard anodizing, such as temperature, current density, kind of alloy, and bath composition, were investigated.
Conditions: Bath composition (1) Sulfuric acid 100g/l+Oxalic acid 15g/l
Bath composition (2) Sulfuric acid 380g/l+Oxalic acid 10g/l
Bath temperature……-5-+10°C
Current density (D. C.)……2.0-4.0A/dm²
Kind of alloy……61S, 24S, AC4A (Silumin), AC4B
The relations between bath voltage and anodizing time are shown in Figs. 2, 5, 7, 9, and 10, from which it was found that the higher the temp., the lower the current density, and the lower the bath concentration, the easier and the thicker was the coating forming. It was also found that v. s. temperature relations, especially with 61S alloy, could be represented by the following equation:
x₁-x/y₁-y=mx+C
“Burning” and its prevention was also discussed.

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Leveling action on bright nickel plating, with saccharine, naphtalenedisulfonic acid and butyndiol as addition agents, was studied by microphotography. Levelling ratio was increased in proportion to the quantity of butyndiol and decreased inversely to the quantity of current density and magnitude of notched angle on the surface of base metal (copper). Residual stress in metals electrodeposited from watts type bright nickel plating bath with saccharine, ethylenecyanhydrin, gelatin and butyndiol were measured by Hoar method. When saccharine and naphtalenedisulfonic acid, were added, compressive stress remained in the electrodeposit, but when added ethylencyanhydrin, gelatin and butyndiol, tensile stress remained.

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Conditions, such as of potential difference between Cu/Cu⁺ and Sn/Sn⁺⁺ in the baths, over all chemical reaction, effect of additional agent, deposition rate of tin at various temperatures, corrosion properties of the specimen in neutral and acid aqueous solutions, etc., for immersion tin-plating on copper in the following 3 kinds of bath were investigated:
(1) NaCN 185g/l, NaOH 22.5g/l, SnCl₂⋅2H₂O 18.5g/l
(2) Thiourea 55g/l, Tartaric acid 39g/l, SnCl₂⋅2H₂O 6g/l
(3) NaCN 85g/l NaOH 54g/l, Na₂SnO₃ 48g/l
In these baths, cyanide and thiourea are working as complicating agents of Cu⁺ and Cu⁺⁺ ions, so that the activities of these ions are reduced largely until the potential of Cu/Cu⁺ in these baths become more negative than that of Sn/Sn⁺⁺ by 300mV in bath (1) and by 200mV in bath (2) at 17°C.
Total stoichiometric relation can be expressed as follows:
Sn⁺⁺+2Cu=2Cu⁺+Sn……for bath (1) and (2)
Sn⁺⁺⁺⁺+2Cu=2Cu⁺⁺+Sn……for bath (3)
Addition of 0.1 to 1.0% of anionic surface active agent, “Anionic 08”, reduces markedly the deposition rate of tin in bath (2), but showed very little effect in bath (1). In corrosion test of the specimen in dilute HCl, mostly Sn⁺⁺ ion came into solution as expected, however, in water containing Cl₂ copper was dissolved more than tin.

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