Creating reflective surface

if the material is sturdy enough, hand polish; years ago Reynolds Aluminum held an "in-house" contest with employees to determine how to roll aluminum thin enough for it to become "foil"; up until that time, any efforts to roll thin resulted in inconsistency and damaged material..............the answer was to roll two pieces at the same time; and a result of that was that the two mating surfaces were compressed to the point of becoming shiny.

For what purpose? The reason I ask is that I was playing with a thermal imager a few weeks ago and discovered that aluminum has a perfectly reflective surface - in the infrared spectrum.

We kids polished the cases of our motorcycles to a mirror like finish using "never-dull".

I wanna polish about a half a m2 sheet aluminium as shinny as possible. I think you might have solved my problem. I just need to work out what method is the best to make it fast and even.

For us kids the rough brown paper hand towel found at the gas station worked best to buff the polish to a sheen.

I wouldn't be asking all this if i could find a large enough piece of reflector out of any of those fluorescent lights because the thinner the better, but it should be as shinny as them to reflect sunlight as efficiently as possible.

Those reflectors are sufficiently shinny enough for most practical purposes so much so that anything more would be an over-kill considering the costs.

I'm supposing it is that you are trying to find a use for material you possess.

CR4 examined a question of reflective surfaces not long ago in which Mylar was recognized as very thin yet extremely reflective and fairly inexpensive to boot.

Hello Isti80,

Not knowing the application I used mylar over wood for some large reflective surfaces.

Outside wood may not be practical, Aluminum will oxidize over time but you can clear coat it. Many telescope mirrors are coated with aluminum then a clear coating but the cost for that is high due to the perfection involved.

Brad

There are polishing compounds that are used with buffing wheels to polish aluminum very well, without a lot of work. Try Sears, and Grainger. Both have compounds and buffing wheels. Another place to try is a truck chrome shop. Larger truck stops will have the compounds and some really great metal polishes. You can find some polishes at the larger auto parts stores also. But Mylar is very good if on a flat surface.

I just bought a buffing wheel and some polishing compound at the Home Depot. It worked great. I polished some aluminum mouldings off of an old travel trailer. The mouldings were around 50 years old and severely oxidized. After buffing for a few minutes, the were extremely shiny, just like looking at a mirror.

Caterers aluminium foil has a highly reflective surface and is very thin. (This can easily be obtained in rolls up to 500mm wide.)

Are you wanting to polish a piece that you have or do you want to obtain highly relective material?

We also buy "polished" aluminium strip to press out reflectors for use inside lamps. Taht stuff's great or we vacuum metalize onto plastic surfaces, but half meter square is fairly large for that porcess.

Hello Isti80, like some have said using metal polish with a buffer is the way to go.

I would suggest getting a buffer/polisher like they use of polishing the paint on autos.

They are variable speed with interchangeable pads.

Start with a rouge paste of course/medium (green)then proceed to a fine/x-fine (red) then use the metal polish for aluminum(semichrome polish I have used it on all metal) The rouge pastes will give you a smother finish than the metal polish by its self. Also with the polish pads only use one with each compound don't cross containment.

Once you have the metal polished, there's a product called ZOOPS. It eliminates the oxidation that starts almost as soon as you finish polishing.

Hope this helps some.

And if the mylar is an option you can use, Try finding some old but not too old projection T.V.'s most now have a mylar reflection mirror in the back to fold the picture to the screen. Some tv repair shops will give them to you or for a small charge.

metalSmith's

Do you realy think mylar is reflective enough? I had a quick look on the web but they were all colored and I need silver.

Anyway, I will pop into one of these TV repair shops and they might be able to help.

Thanks for the advice.

Thanx all!!!

I think I go with your suggestion, metalSmiths. Use a a little bit of this and a little bit of that and finally some ZOOPS.

your welcome glad to be able to help.

metalSmith's

I think your best bet is to try Mylar...

The best, and cheapest source of this is a "Space blanket"...

This is a thin, highly reflective, silver Mylar sheet (3'x6') that is a couple of dollars (U.S.) and can be found on the internet...

Do a search for "Space Blanket"...

Hope this helps...

Years ago there was a product called "Glass Wax", problem is I haven't seen any in decades. It was the best I ever used. However, I Googled it and found "Window Glass Wax" is available.

The surface finish you refer to is done by vapor deposition or "sputtering". The surface must be smooth to start with as imperfections will show up. The base material has to be harder than aluminium or molded on a surface perfectly polished. The Aluminum is almost impossible to polish to extreme smoothness because of it's softness.

The highly polished surface you referred to on fluorescent lights is vapor deposited. That is usually performed on plastic substrates. I think aluminum can be mechanically polished but it can also be purchased with a mirror like finish or electropolished.

Morgan,

How durable is electro-polish you're referring to or is it vapour?

I saw once on display a huge collapsible parabola reflector that was made of exactly the same material as those fluorescent reflectors. They are very good and I assume they must be cheap because they're widely used on a tough kind of aluminium therefore, scratches and other smaller marks don't seem to matter to a degree.

Anyway, sound like both methods are beyond my scope. I can tackle polishing but definitely not the other methods you mentioned.

Electropolishing is a chemical process used on wrought metals.

The vapor deposition process takes place in a vacuum chamber where the aluminum is vaporized in a crucible and is deposited on the object, which may or may not be metal, in the chamber. Large parts are done in what are called junk coaters. The collapsible item you saw was probably vapor deposited. The "aluminum foil" on gum wrappers is vapor deposited on a substrate and later stripped of and glued to paper.

If you have a metal part, it could be vapor coated but the base material would have to be pretty good.

I just wanted to know more about something as common as the fluorescent light-reflector. What you have told me I well nd truly have to give up on getting a surface like that. I wonder, how well aluminium can be polished? Could it be better than the surface of a saucepan-lid or that is the best you can get? The problem with that of course is it wouldn't keep its shinny face for long though. I also assumed that in a larger quantity the fluo-reflector material is a cheaper option and could easily be protected from dust and and grits by keep it behind a perspex that can be cleaned conveniently.

Electropolishing uses a chemical bath to dissolve the microscopic peaks on the surface, leaving a smooth surface, the same as mechanical polishing but without the inevitable microscopic abrasive finish left after using any polishing compound. Like a mechanically polished surface, it must be coated to protect against oxidation and abrasion.

There are polishing compounds used in the eyeglass industry depending on how crazy you want to get. As I recall, it took something like two years to polish the ill-fated Hubble Telescope mirror to a near perfect surface.