Factors involved in formation of penetrant testing indications

The process involved in the formation of indications in the penetrant testing may be considered as below. On the surface of a test object, oil, grease and other contaminants are removed by cleaning, the penetrant is applied, and after in elapse of sufficient penetrating time to, the liquid penetrated into a defect is drawn out to the surface film from the defect into the developer film formed on the surface of the test object at a later stage. Thence, the penetrant spreads over on the developer film to display indications. During such process of formation of indications, many contributing factors may be mentioned. In this paper, such limited aspects as the removal of moisture content, the removal of excess penetrant from the defects by means of solvent aerosol, the effect of developer film thickness and prepagation characteristics of indication on the developer film are taken up, and the effects given by these factors on the formation of indications are investigated through experiments