Does anyone know why the upper and lower have small white dots all over after anodizing?  They are New Frontier AR-9 parts.

This is only my second attempt at anodizing. I did one with black RIT die a couple years ago, also a New Frontier lower and it turned out pretty good just a little to glossy. So this time I blasted the lower with 150 grit to try and knock the gloss down a little.

Other wise I used the same process of degrease, clean, clean, clean. Desmut for 5 minutes,  distilled rinse/soak,  into acid bath 12 volts, lower was about 4 amps and upper was 6.5 amps. Used the 720 calculations for time,  distilled rinse , into RIT gray synthetic dye for 20 at 130-140 degrees, then boiled for 20 minutes.

I’m pretty sure they are 7075. The upper was very rough texture compared to the smooth lower so I didn’t oxide blast that one. The only odd thing I noticed was there was some small debris particles in the acid bath. This was the same acid I used from my first lower and I didn’t notice it until I agitated the parts while anodizing. I’m guessing it came off the lead sheet that was left in the acid for a couple years.

What would cause this to happen?

Crap I can’t upload a picture.