To get black coloured coating using for art & craft, especially for wrist watch dial, electrodeposition of PbO₂ from alkali solution were studied. The results obtained are as follows:
(1) Bath composition used: NaOH 40gr., Pb(OH)₂ 12.2gr., Resorcin (addition agent) 1gr., H₂O make up to 1L.
(2) Optimum conditions of electrolysis:
Bath temp. Anodic current dencity.
°C mA/cm²
60 10-16
70 14-18
80 16-20
(3) To prevent of change in colour of coating film, suitable additional agent, for example, resorcin, tanin & potassium permangate etc. must be used.
(4) The compositon of film electrodeposited from the solution above mentioned was recognized to typical PbO₂ by X-ray defraction and chemical analysis.

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Aluminium alloys have been used for ship, architecture, railway, motor car, bicycle chemical machine, optical instrument, furniture & etc. In many cases, Al-alloys are usually painted to protects from corrosion, It is interesting that the Synthetic resin, shown the conspicuous advance are applied for this paint.
Vinyl acrylate copolymar resin, Phenolic resin and phthalic resin paints in the Synthetic resin are good in comparision with paints of Benzyl-cellulose type used to Aluminum alloy for the airplane in our country, and we explane the influence of surface treatments ion the aluminium alloy, for paints Alumite treatment has good effect, and Alcohol phosphate, Chromodiying, Alrok, Alroksealing method followed it.

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By the requirement from practical application, corrosion tests were carried out for soft iron specimens coated with several kinds of sprayed metals. The results are as follows.
i) Most of the specimens are not enough resistant to acid water solution, even to organic weak acid solution.
ii) To the solvents such as CH₃OH, C₂H₅OH and C₆H₆, specimens are quite resistant, but to the solvents such as CCl₄, CHCl₃ and CS₂, they are not enough, especially when the solvent contains water.
iii) It was seen that when the sprayed film is electrochemically nobler than the base, the base is corroded primally, while the base is nobler, the film is corroded and the base is protected.

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Three methods of testing the average thickness of Zinc coating on iron wire, i. e. HCl-SbCl₃ metlhod, Eiectrolytic method, & Gas-evolution method were compared. Samples used were, No. 1-hot dipped at 480°C, No. 2-at 600°C, No. 3-at 450°C without wiper, No. 4-at 450°C, and No. 6. 7. 8- electroplated ones.
Results obtained:
1) As the electrolyte for the electrolytic method, Britton's solution containing NaCl was found to be better than 1N-ZnSO₄ solution.
2) In the gas-evolution test, dil.-H₂SO₄ (5% for hot-dipped, 10% for electroplated) must not conain arsenious oxide.
3) The electrolytic method gave smaller values than those of HCl-SbCl₃ method, and the gas-evolution method gave greater values.

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