NYALOX Brushes

I've been working on an aluminum W.I. for several weeks now and was needing something to clean in the valleys and peaks to try and remove 80+ years of baked on crud. I had to make a trip to the local hardware and came across this abrasive impregnated nylon bristle brush. I bought the blue one (240 grit) simply because I wasn't sure what effect it would have on the aluminum. To my surprise it worked great. I'm not sure how it will do on cast iron but I have some experimental pieces to try on. I've attached the link for anyone interested in checking it out.
http://dicoproducts.com/nyalox.html

I've used the 2.5" grey cap brush on several CI pieces I've restored. After the rust and old seasoning has been removed, if the cooking surface feels etched or has any discolorations from old carbon deposits the brush cleans it right up.