I recently picked up an old A1 upper.  It's in pretty good shape, but has a sufficient number of scrapes and dings.  I would like to sand some of these areas down and smooth them out.  I will then apply a coating of Moly Resin to the upper.  My question: how "deep" is the anodizing?  I don't want to sand through it, though I don't know what effect that would really have with it be coating in Moly Resin after the fact.

Anyone have any thoughts?

Thanks

Anodizing is typically less than .002" deep, often less. It isn't hard at all to sand thru an anodize coating, even with fine sandpaper.

You will most likely loose the anodizing where you sand. As FB41 says... it isn't very thick.

Wash with dish soap and rinse well, dry and soak in acetone for a couple hours before spraying your finish. II am not familiar with Moly resin, I've only done Gunkote. I suspect the prep is the same.

I media blasted most of the anodizing off 2 lowers I had already anodized and didn't bother to reanodize.

Thanks for the feedback.  I might just clean it, coat it, and see how it turns out.

If you just have some marks in the anodizing, you can also touch up with some aluma black instead of painting the whole thing. Not trying to discourage you, just another option to consider.

After machining, anodizing 3 80% lowers I thought Gunkote was going to be the easy part...just my luck it was the most work for me.

I'm far from an expert, but the Moly Resin worked well for me in the process of building a 604 clone.  I wanted to match the upper and lower, in color,  and found the product to provide a close match to the original Colt Grey.  I used an old toaster oven, hair dryer, and a cheap airbrush setup from Amazon.  I'm pretty happy with the results. Thanks again for your feedback.