Must be 5 years since i last did any sulphuric anodising and at that was rather hit and miss.
The main problem at time was gaining information which seemed a highly guarded secret around 2001. There were only three sites that gave a how to but every one left something out or even told porkies (lies.)
All were different including voltages, acid mix, duration and to my bug bear the contact with part to be anodised.
Most recommend an aluminium wire wedged in to the part, for me a breakdown wthin 2 minutes every time even threaded in. The only method short of trying titanium was aluminium 6082 wedge shaped and tightly screwed in to a hole before and after chemical cleaning with hydrochloric acid.
Have even done hard anodising twice but couldnt repeat next time.
For me 17 to 19% sulphuric mix around 13.6 volts measured in hours. Many can do this in minutes.
One thing i did have to figure out was the dye needed warming up but not too much to seal the part. Tryed all dyes i could gey my hands on, literally nothing worked except the powder the pros use.
Thinking back and may be another porky after dipping in colour for a period of time, it was supposed practice to then boil the part in water to seal the colour. Seems now i should have used acetate.
Over the years did have a few parts come out quite professional.
Heres a bead blasted item
Come out a bit matt this one.
Bit matt this one blue tint opaque most come out purple to brown
One of these days i will get it up and running again, got two PSU 0-30V ones digital twin output the other a backup an analogue from Maplins.