gloss white paint or shiny zinc plate for a reflector? - Lighting

titan97 · 08-01-2005, 09:12 AM

You'd think that someone like me that works in the metal finishing industry would know more about light and reflection. Well, I know how to make something shiny and chrome plated, but that doesn't help me here.
Anyway, I'm building a light box for my tank that will hold 4 24" ODNO bulbs. I picked up some roof flashing material from my BORG and it is either zinc plated, or it has the shiniest galvanized coating I've ever seen. It is already bent into a V-shape, so I just need to mount my bulbs inside the V and I should be more or less ready. However, I also painted the inside of the box a high-gloss pure white to help reflect any stray light that gets past the reflectors.
My question is this: Should I paint the reflectors gloss white also, or leave them shiny (but not mirror) bright metal? Which will give me the best reflection?

-Dustin

**AaronT** · 08-01-2005, 09:21 AM

Option C: Polish the shiny metal to be even shinier and use that.

titan97 · 08-01-2005, 09:56 AM

I can't polish the metal. It is either zinc plated or galvanized steel. Therefore, polishing it will strip the steel if it's corrosion protector, making it rust very fast. It might be bright for a few days, but it would corrode quickly over a moist, hot aquarium.
I suppose I could polish it and chrome plate it, but that would require some significant effort to do. I'd need to strip the zinc (easy with HCl), degrease the steel (easy), cyanide copper strike and cyanide copper plate (both easy), move the parts to a new plating line and clean them again (easy), duplex nickel plate (easy), and chrome plate (easy). The hard part is finding a way to hold this large piece of sheet metal on a rack designed for parts the size of door handles and faucets. One of my customers is Black and Decker (I'm actually at one of their finishing facilties now, "working"), and they have all the process tanks I would need, but not the rack(s).

-Dustin

MatPat · 08-01-2005, 10:44 AM

Polish the metal and apply a coat of lacquer to the bare metal. As long as you don't scratch through the lacquer you should be good for a long time.

You can buy small aerosol cans of lacquer at most home imporvement centers. Parks is one brand (marketed for exterior brass fixtures) and Deft is another (marketed for wood). Either will work in your case.

Creating a hood is on my to-do-list and I plan on using some aluminum flashing and giving it a polish and a coat of lacquer. Lacquer finishes were great on cars for many, many years

titan97 · 08-01-2005, 10:59 AM

Interesting idea . . . .. I suppose I could take them to my other customer in Tijuana (they have polishing machines), and then laquer it once it has been cleaned. Hmm.

-Dustin

**AaronT** · 08-01-2005, 07:13 PM

Or why not get aluminum flashing and polish that? It's not expensive to get from the hardware store.

titan97 · 08-02-2005, 09:54 AM

I was wrong, it IS aluminum flashing. I was in a rush out the door yesterday . . . ..

However, I will still have the same problem with Al as with steel. Al will "rust", but it will look white and powdery. Look at an old, aluminum fishing boat and you will see what I mean. I work with metals all day, and aluminum is a pain to plate onto just because it oxidizes so damn fast. You might not see it right away, but it will oxidize almost instantly. Because I'm such a lazy and impatient SOB, I went to my local auto parts store and found a can of spray paint that is supposed to be highly reflective. It contains tiny particles of something that acts like a bike reflector or something like that. It looks clear, but when you move it into the light, it really reflects well. It may not be as good as a mirror-bright polished or plated surface, but for a cheap-skate/DIY-kinda-guy like me, it should work well. Of course, I'm putting so much damn light into this tank anyway, I may not need the reflectors. I have a 35 gal hex tank, 24" high, that will have 4 24" bulbs driven 4x ODNO. That should put me somewhere near 170W or 4.8WPG, or ~3.5WPG factoring in the height.

-Dustin

MatPat · 08-02-2005, 10:23 AM

I made a hood for a friend of mine last year with aluminum flashing and it was in great shape in early June when I visited him. I could see how plating may cause some issues with aluminum but a clear coat of lacquer is still pretty easy to apply and is waterproof as long as it doesn't get scratched!

I'm not sure about your paint choice. It SOUNDS like it may scatter the light more than reflect it. Hard to say without seeing it though.

I built a hood for my 30g tank (36"x12") and have two 2x overdriven 36"lamps in it without reflectors. It was painted with gloss white lacquer (I used to work in a cabinet shop) and there is plenty of light in that tank to grow Tonina species and most any other plant I have tried! I don't think you are going to have any lighting issues with your tank other than pruning the plants every couple of days

titan97 · 08-02-2005, 10:30 AM

Matt,
I don't doubt that the lacquer would work great on either the aluminum or the steel.
As far as the scattering vs reflecting point, I might agree with you again, but I will have to wait and see. In any case, the underlaying metal was pretty bright to begin with.
And I can't wait to "have" to prune every other day or so.

-Dustin

MatPat · 08-02-2005, 10:40 AM

Quote:

Originally Posted by titan97

And I can't wait to "have" to prune every other day or so.

I will warn you, it gets old pretty fast