I am open to comments from those with experience in the use of Zyglo fluorescent dye used for leak testing.

Situation is that the dye is taking up to 5 days to reveal leaks in 1/4" thk 304L base material welded with .035" dia 308L GMAW process.

Here in Oregon we have been experiencing temps of 32 deg F low to 55 deg F high. I can only surmise that the temperature of the steel is causing the dye to be slow acting.

Appreciate your input....
Robert

Am testing for leaks using fluorescent dye penetrant (spray can application) on exterior of 3/16" thk. 304L matl 10' dia x 18' L vessel and using black light to reveal discontinuities from interior.

In the past the Magnaflux Zyglo penetrant would reveal even minor, minute cracks within 4 hrs.

I checked the vessel skin and it reads 48-50 deg F.

Tried warming up suspected areas (T-joints intersections) to approx 80 deg F and performed PT, same results, does not reveal discontinuities till dwell times of 2-5 days!

Have changed batch number for PT and still same results.

Would using the white developer work with fluorescent dye penentrant? If so, would it reveal cracks faster?

Have Paint Dept wanting vessel for glass bead blasting but cannot release it till I am assured of integrity.