I always use distilled water for the processes. Our water here, even though public, still leaves mineral spots.
One tip I saw but haven't ried for the stipping part is to use plain rubber cement. The caustic soda will not eat it and it easy to remove.
There will be some leaking around the cement but it is better than elaving important parts unprotected.
A question for you is if you made the parts yourself are they the ones you are using the lye on.
For new parts all you have to do, I have found, is clean them extremely well. For a good job I always use a de-greaser like simple dish soap or I use Purple Power.
I like Purple Power because it will not harm the aluminum and does an excellant job removing grease. I have used it in the garage for years.
After a good wash and rinse I dip it in to an acid cleaner that actually etches the aluminum slightly. I giess you could say brighten.
The one I am using I got at the auto body supply shop. It is called Pro-power Acid Cleaner C-24. The sales guy said the truck drivers use it to clean the big aluminum tanks of tractor trailers.
Also he said the fireman use it to clean aluminum parts on some of the trucks. It is not a good thing to clean sensitive aluminum parts like wheels on your car though.
Anyway this particular product contains sulfuric acid, phosphorics acid and hydofluoric acid. It is highly concentrated and gets diluted 10 to 1.
I have a container premixed that I use to dip parts in over and over again then spray them down with distilled water.
I have found this process to prep the parts perfectly before the anodizing bath.
Once again I learned this through trial an error and lots of research.
Once again I need to stress safety! Safety! Safety!
Don't want to scare anyone off from doing anodizing. You just need to be careful and not rush.
I find all of it less danagerous than getting by the wheel of the car.
Once again I hope this helps and I am working on a process of how I anodize but it could take a few days being I am in the middle of relaying out the shop.
Have a great day!
Ed