In the last issue of this newsletter, we discussed the work being done at Iowa State University with regard to penetrant inspection. To reiterate the place where you can get all of the detailed information presented at the Spring ASNT meeting, go to www.cnde.iastate.edu/faa-casr/fpi/ Once at this site, click on “Technical results”. This will lead you to a page that lists the various presentations. In this issue we want to discuss the effect that developers have on the indication brightness, and if you wish to review the full text relating to this, when you are on the “Technical results” page, click on “Developer Studies”.
We have taken some of the data from that study and presented it in a slightly different format. These data appear in the graph on the next page, and the data are arranged in order of increasing indication brightness. This allows one to easily see the comparison between what one is presently doing and how that compares with other methods of developing the indications. As examples, one can see the comparison that is based on the use of dry powder (Form “a”) developer in a dust chamber, and the average brightness of the indications, based on the average of indication positions, i.e., on top, side, or bottom of the part. The use of water soluble developer not only deals with the problem of the orientation of the cracks when using dry powder developer in a dust chamber, but produces indications that are approximately 4 times as bright.
When using water suspendible developer, the indications are approximately 8 times as bright. Finally, as every inspector knows, using form “d” aerosol developer produces indications that are about 12 times as bright as the average dry powder developer when used in a dust chamber.
Once again, we strongly recommend a review of the complete presentation that is on the web site.