Zyglo® ZP-5B is a white powder developer which is to be dispersed into water. It disperses quickly to form an opaque white suspension, but must be continually agitated during use to ensure uniformity of mix as developer will settle out on standing. ZP-5B forms a uniform white coating which enhances fluorescent indications formed by Zyglo® penetrants. At higher concentration, ZP-5B forms an opaque white coating which provides contrasting background for Spotcheck® indications.

METHOD OF APPLICATION

Zyglo® ZP-5B can be applied by immersion dip, spray or flow on techniques. If the immersion dip application is used, care must be taken to avoid transferring excess penetrant into the developer bath. Complete removal of surface penetrant will prolong the developer bath life. The developer bath temperature should not exceed 120ºF.

If the spray or flow on techniques are used, care should be taken to avoid foaming as foam bubbles will cause holes in the developer film when they break. Use Magnaflux® ZAF-2 Anti-foam if necessary. The developer is applied after the surface penetrant has been removed. For best results forced warm air drying (140ºF/60ºC) is recommended. The test piece should be removed from the dryer once developer is dry, as prolonged drying will not enhance performance and can bake developer making post inspection removal difficult.

In Zyglo® fluorescent penetrant applications, cracks will appear as bright yellow green lines, porosity as spots. A general greenish developer film indicates incomplete removal of surface penetrant. In Spotcheck® visible dye applications, cracks will show as vivid red indications against the white contrasting background formed by developer.

The developer film can be washed off with water spray. If the coating has been baked on or does not wash completely,brushing should be employed along with the water spray.