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Old 03-18-2016, 04:46 AM
Kabous Kabous is offline
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Default Aluminum alloys with highest reflective finish

I've searched but couldn't find much on the subject of which aluminum alloys will produce the highest reflective finish. Read somewhere that the harder it is the more luster can be had by polishing. So I guess that the 6xxx series should be much more reflective than the 1xxx but found on the net that 1050 can also be highly reflective. Or is that just a kind of lacquer sprayed on?

I am planning to start shaping some panels next week, weld and polish them up and see what kind of a finish can be achieved.

So I was just wondering which alloy to get, over here in Cape Town, only 1050 and 6082 are readily available. Which alloy would have been ideal if availability wasn't the problem?
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Old 03-19-2016, 03:59 AM
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Z5Roadster Z5Roadster is offline
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Think part of what you are asking depends on how good you are at finishing a panel off before polishing, I sway towards the polished Cobra body and if you are the same my thinking is I do not have enough yrs left in me to achieve that standard. Take a look here this is general purpose aluminium for panels, I forget the spec. http://www.allmetalshaping.com/showthread.php?t=10090 there is a shot about 4 down on the 1st post, all panels were only wheeled and then quickly polished with brasso a domestic metal polish. Good luck.
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Old 03-19-2016, 08:50 AM
custommetal custommetal is offline
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Almost anything can be polished to a highly reflective surface. What many people don't realize is shiny is not polished. Being in the tool and die industry 40 plus years I have polished surfaces to better than a chrome finish. The basic premise of all polishing is to sand the surface with progressively finer grit paper or abrasive. Keep it clean between grit changes. With each grit change you go 90 degrees or perpendicular to the last sanding pattern and sand until the coarse scratches are gone. The purpose of this is to realize that in a highly reflective surface if all the sanding scratches go in the same direction the surface will appear shinier. Sounds like a lot of work, and it is, but give it a try on some scrap. Since aluminum is soft maybe start out with 600 grit paper and go up from there. If you have some auto paint compounding materials try them and treat the surface as if it were a painted car.

George
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Old 03-19-2016, 02:40 PM
Kabous Kabous is offline
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Thanks George, after reading your post I found some videos and the best looking was when the guy did all the polishing in one direction like you said, make sense when you think about it. He was using an orbital sander and it still looked good, so using your 90 deg technique should look even better. Will definitely give it a try and post some pics.
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Old 03-19-2016, 06:50 PM
Richard-S Richard-S is offline
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Over the years I have polished a good bit of aluminum in my sculpture work. It is mostly 1100, but there have been other alloys.





What I have noticed is that the main difference in the different alloys is the color.
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Old 03-20-2016, 06:01 AM
Kabous Kabous is offline
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Richard, can you give an idea which alloys is lighter in color and those who are darker?
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Old 03-20-2016, 08:27 AM
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Even simpler way to think of polishing is to look at a pond. In windy weather there are no reflections because the waves cause the reflected light to go in many directions. No wind and a smooth surface reflects light in the same direction so appears shinier or more reflective. So treat the metal as if it were a fresh coat of paint with runs, in this case small dents....remove them. Then orange peel or rough surface, sand with finer grits of paper. And a buffer is the same thing...the different rouges or compounds are just different grits.

George
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Old 03-22-2016, 01:34 AM
crystallographic crystallographic is offline
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Quote:
Originally Posted by Kabous View Post
I've searched but couldn't find much on the subject of which aluminum alloys will produce the highest reflective finish. Read somewhere that the harder it is the more luster can be had by polishing. So I guess that the 6xxx series should be much more reflective than the 1xxx but found on the net that 1050 can also be highly reflective. Or is that just a kind of lacquer sprayed on?

I am planning to start shaping some panels next week, weld and polish them up and see what kind of a finish can be achieved.

So I was just wondering which alloy to get, over here in Cape Town, only 1050 and 6082 are readily available. Which alloy would have been ideal if availability wasn't the problem?
When we were sourcing reflective panels for solar reflective dish cookers the alloy was pretty much the 1050. The mill finish was excellent and the polish was like a glass mirror - no grain, no polish marks, special product.
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Old 03-22-2016, 12:57 PM
Kabous Kabous is offline
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Kent, we are stuck in South Africa with very few alloys, only 6082 and 1050 are readily available, no 3003 at all. I am trying to source 5xxx and after I read your answer on another thread especially 5052 but so far no luck. Would you use 1050 for a Cobra body and if so, what gauge? Any other precautions?
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Old 03-22-2016, 01:44 PM
crystallographic crystallographic is offline
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Kent, we are stuck in South Africa with very few alloys, only 6082 and 1050 are readily available, no 3003 at all. I am trying to source 5xxx and after I read your answer on another thread especially 5052 but so far no luck. Would you use 1050 for a Cobra body and if so, what gauge? Any other precautions?
Cobra = 1.2mm as standard, 1050 would be suitable.
"heavy body" would be 1.5mm.
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