Specular aluminum - should I bother?

[Matak]

Hi all, first post.

My hobby is keeping aquariums, particularily planted tanks. Planted tanks require plenty of light and one of the objectives is to get as much light into the tank as possible. The absolute best way to re-direct light away from the flourescent light fixture and into the tank is by using a parabolic shaped specular aluminum reflector. Sure, you can buy these reflectors, but they are not cheap. Especially when you need 4 - 48" X 7" strips and 2 - 24" X7" strips and 20' of 2" strips. Besides most planted tank owners are DIY by nature.

I have already purchased a nice sheet of aluminum that is just the right thickness and I have wet sanded it with the following grits: 400, 600, 800, 1500 & 2000. Some parts of it are quite reflective, while other sections are pretty hazy. I realize that I need to polish & finish it to get it to be truly reflective.

So, is it worth it? Am I in for a lot of work? Will I save any $'s? Any advice will gain my undying respect

[pickleboy]

Re: Specular aluminum - should I bother?

first off welcome to the forum. as for being worth it only you can answer that bro. first i have a few questions for you to be able to give good answers.first, what is the thickness of the alum.in question. second, what tools for polishing do you have at your disposal. do you know the alloy of alum. you are using. this will help to determine the best course of action. caswell offers lots of options for polishing aluminum so we should be able to guide you in the right direction. let me know these answers if possible and i can make some recommendations.

[mpierich]

Re: Specular aluminum - should I bother?

What is "specular" aluminum?

If you have it up to 2000-grit already, I would start with red compound on a loose flannel wheel, low rpms and work backwards to white compound if need be. You don't want any heat buildup or it will likely warp on you.

Trial and error will be required so do one small corner til you get it right.

[Matak]

Re: Specular aluminum - should I bother?

Specular aluminum is the most highly reflective surface you can get, that and mylar, the plastic foil you would find inside bags of potatoe chips and on helium balloons. It is much more reflective than a glass mirror.

Here is a link to the aluminum that I am using: http://www.dundasjafine.com/products...pairrolls.html It isn't that thick, it is fairly easy to bend, which makes it perfect for shaping into a parabolic shape. Gotta go to a company Christmas dinner, I'll give more info when I return.

[Matak]

Re: Specular aluminum - should I bother?

Ok, it's fess up time. After I wet sanded I also tried to polish with a angle grinder and a wool bonnet, and a red & blue compound I got from a local auto supply store. Well, the polishing worked only marginally, it at least took out the hazy look, but it really didn't improve the reflectivity (is that a word?) of the aluminum. The bonnet heated the aluminum so much that it melted the paint of the slab door I was using as a work bench to the aluminum and I had to peel it off the door. It also took some wood grain with it. It also overheated my angle grinder and it stunk out the house with the smoke that came out of the motor housing. The heat that it produced also warped the metal, but thankfully not to a degree that I can't work with. And the wool bonnet caught the edge of the thin aluminum and caused it to crinkle in more than one spot.

But other than that it was a success

Thats when I looked online for a solution. Glad I found this Caswell sight.

BTW, if any of you polishers get the notion to venture into an untouched industry, consider mass producing specular aluminum. There are plenty of planted tank owners and hydroponic vegetable growers (I'm sure they're just growing vegetables) that would love to find a source of sheet specular aluminum for DIY rather than pay the big$ for the pre-made light fixtures.

[mpierich]

Re: Specular aluminum - should I bother?

Well, like I said the heat will be a problem. Would rather see you use a 1500 - 2000 rpm drill instead of the angle grinder for that reason. That machine's rpm's are much too high for color buffing, especially with any wheel larger than an inch or two.