Thanks Uncle Babba for your promt reply

This is for a science project. I need Al pieces of different roughness ( measured using a profilometer) which I am able to make using different grades of emery paper. What I'am not able to do is to make the smoother grades look like a mirror and reflect more light while the rougher grades are having visible scratches.

My procedure is :

1) Procure the Al pieces ( 3 x 3 cm), they are already quite smooth as sold commercially as Al sheets (20 gauge)

2) Take the reqd grade of emery paper and polish it for 2 mins by attaching it to a spinning wheel on a polishing machine.

3)600+ grades are quite dull in appearance.

Is it because I'am not working my way down through each grade and straightaway going to the smoothest grade ?
Also I'am not using any polishing/buffing process. I think the emery itself shud do the job..


Please Help

 

Go to page 1 of this thread and read teh original post - the info is all there.

 

Hi Dr.Evil,

I have seen the first page. I still need to know how to remove the black colouring i get when polishing with grades 600+ which I do not get while polishing with grades lesser than 400..

Please Help...

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Hi Doc,

I have read the first post in the thread. I want to know how to I avoid the grey colouring that happens when polishing with grades 600+. It's like a fine material that is not removed by water /acetone. Also this does not happen for grades lesser than 400. It's only with the smoother grades.
Also I;am not using any buffing or polishing agent..Cud this problem be because I'am not working my way down to the smoother grades and instead just using the required paper only (since the initial pieces are itself quite smooth)

Please Help...I'am a little desperate now, as this is part of my project due for completion soon..

 

Aluminum will always leave dark gray deposits unless a buffing agent is used, hence the reason for needing one. Even just friction with plastic (such as in a water bottle cage on a bicycle) will cause ugly gray streaks on the plastic that are almost impossible to remove.

 

I think using a die grinder with a buffing wheel and some aluminum polish will help a lot.

 

If you need to maintain the rough finish and just remove the black then just use polish and a rag. That rough finish you are talkin about is known as a brushed or satin finish.

 

I use Muratic Acid with rubber gloves and fine steel wool,then Mothers.

 

great write up! Just wondering how you keep it looking good once you have it all polished up? just regular coats of the aluminum polish?

 

I usually polish it up once a year with mothers, otherwise a few squirts of windex throughout the year will keep most of the debris and moisture loose and away.....

 

and know we know and knowing is half the battle G.I. JOE