Material for scrubbing Cu-clad boards

[Sarason]

This is for those of you who are making their own PCBs for hobby,
prototyping and low-volume production.

I've seen things like fine sandpaper and steelwool recommended on
hobbyist websites for cleaning copper-clad boards prior to
transferring the pattern and etching. 40 years ago, I used wood
ash. It worked quite well but wasn't always readily available.
Then I tried tooth powder as it's more abrasive than toothpaste.
It sort of worked, but required too much scrubbing. Then I got
the idea of using household scrubbing powder. It works fast,
having just the right amount of abrasive property with no danger
of inflicting deep scratches. Vim and Biz are two popular Indian
brands.

I feel no need to look for a better material, but I'm curious
about what others are using.

After many years of research and cribbing from professional PCB
manufacturer techniques. There is a trick to this. Industrial
manufacturers go alkaline clean. A good product with NaOH detergent like
dish washing detergent. Then a weak acid cleaner. like 5% Ammonium
Persulfate. This microetchs the surface to allow good adhesion of the
dry film. The acid removes the copper oxide while the alkaline solution
strips any grease from fingerprints etc.

 

[pimpom]

Neat, India to the East of Bangladesh.

Yep. Joined to the main part of India by a narrow strip of Indian
territory to the north-west of Bangladesh.