Is there any other good etch for aluminum weld microstructures other than Keller's?

We have something that works for macros but we need a good swab etch for revealing microstructures and micro cracks.  We want it to be a swab etch too.

Our chemist has issued dire warnings regarding the dangers of using HF in Keller's - including lung, heart and bone damage from the tiniest exposures. She is refusing to have anything to do with using the HF component.

We currently use NaOH and a 50 50 with Nitric and HCL I think but they are only good for macros so far and they leave the specimens too pitted to reveal any micro cracks.

We are welding 6050, 6080, 1010, and 1030 I think.

Steve

Steve,   I'm not sure how much this differs from the current etchant you're using, but AWS D1.2, Annex H,  indicates a basic etchant of 20% sodium hydroxide at 120F,  rinse in clean water,  If desmutting is necessary to reveal weld boundaries, a concentrated nitric acid dip at room temperature should be used.  Rise thorougly.    I would think you'd want to limit the time exposure in the acids to minimize pitting.

ASM International handbook Vol 9, 9th edition mentions an elecctrolytic etcch with Barkers reagent  (4 -5 mL HBF4 (48%),  200 mL water.      Use aluminum, lead or SS for cathode,  specimen is anode.  Anodize 40 - 80 s at approx. 0.2A/cm2  (1.3AA/in2, or about 20V dc).   Check results on on microscope with crossed polarizer.     Not sure if this etchant is practical for you, though.