Fixing Mylar to the canopy....arghhhhh!

[Paulus]

Morning All,
My new reef's almost ready for water but I've had a nightmare this weekend with the mylar I was planning to use as a reflector for the 330 watts of DIY compact fluorescents I'm wiring up.

I used epoxy resin to try and glue the mylar to the pre-painted underside of the lid but it wouldn't hold. I used a wallpaper seam roller to try and flatten the mylar out after applying a generous amount of adhesive. But the edges decided to roll-up and the whole thing turned into an epoxy and mylar mess.
The epoxy ended up everywhere and it took me 3 hours to get all the epoxy off!!!!

So, my question is.....

Do I just repaint the hood with white gloss paint or,

Is there a better/easier type of adhesive I should be using??

Any ideas and/or help would be very much appreciated as the whole build has had to stop because of this problem.

Cheers,
Paul

 

[hmott]

can't help on the mylar but I'm pretty sure you don't want gloss white, you want flat white. Double check that though I'm not 100% sure on it.

 

[sales weasel]

I've used 3M Super 77 spray on adhesive for lots of things...just not mylar. I can tell you it is VERY tacky and when I've used it, everything stayed. You can buy it at Home Depot. You could try it on a small piece to see how it holds. The only problem I can imagine is wrinkles. This stuff won't allow you to do much smoothing once you stick something to it. Also, you should use it in a well ventilated area.

As for paint: everything, I've read says to use flat white, not gloss.

 

[Paulus]

Sounds good. What about matt white?

Sounds good. What about matt white?

Thanks guys for the replys.
So a good quality spray-on adhesive from the home depot should be ok? Great! I'll stop off on my way home.

Just out of interest. The inside of the hood is current painted satin white. Is it worth me trying the mylar again? Is the matt white just as good as having mylar????

Thanks again & regards, Paul

 

[gath2]

After applying the epoxy, is it possible to add some type of mechanical fastener to hold it as well. I was thinking screw in some thin molding strips around the edges to hold it in place. Then tape off the mylar and paint them white if they are not white to begin with.

 

[sales weasel]

Re: Sounds good. What about matt white?

Re: Sounds good. What about matt white?

If you try the spray on adhesive, try it with a small test piece first. If possible, take the canopy outside. Like I said before, you'll have a tough time smoothing out wrinkles if you use this stuff. It adheres instantly.

<a href=showthread.php?s=&postid=7198434#post7198434 target=_blank>Originally posted</a> by Paulus
Thanks guys for the replys.
So a good quality spray-on adhesive from the home depot should be ok? Great! I'll stop off on my way home.

Just out of interest. The inside of the hood is current painted satin white. Is it worth me trying the mylar again? Is the matt white just as good as having mylar????

Thanks again & regards, Paul

 

[dc_909]

My experience with mylar is that it worked good for awhile, but then the heat from the bulbs made it brittle and pieces chipped off when you touched it. I would try something different.

 

[gobygoby]

I thought white paint was more reflective then mylar anyway?

 

[jimmyj7090]

Yea, forget the mylar, use flat white paint or shell out a few $ for a commercial reflector.

You'll spend $25-50 getting a good commercial reflector(s) but it's probabally worth it.

As I understand it, the effiency of lighting over a fish tank is affected at least as much by the reflectors shape as it is by the reflectors finish. (Don't qoute me on that exact statement, but get my drift..) Mylar is a few % more reflective than flat white paint, but neither is easy to form into an ideal shape - double parabolic or something like that is more or less ideal. You can buy a commercially made reflector(s) for not too much $ and that may cost you less than the time and materials it would take to DIY it and get even close to the same potential. To properly align the mylar would probabally be almost impossible and I don't know how it would stand up to the heat. You could make a good reflector shape out of wood and paint it or adhere the mylar, but You'd probabally still end up with a lower performing final outcome and more $ spent getting it right (close at best).

I use 2 commercially made reflectors, one over each 250W MH. These are mounted in a plywood box pendant. Using the commercial reflectors allows for an airspace above the lights that I think helps with cooling (fans mounted in the top of the box). Really easy to build and set up, no negatives IMO.

I'm a committed DIYer, but IMO reflectors is one thing that is worth just buying.

Just my $.02

 

[jay24k]

Mylar is quite a bit more reflective then white paint. White paint is the worst reflector beside no paint. I would also just buy a good reflector. Less of a headache and if you add up your time and cost, it probably was equal or close to it. Sanjay has a study of measuring light and did it with white and other reflectors. There was quite a difference.

 

[Paulus]

Wow! Thanks for all that, It's been a real help. I think I'll get some decent reflectors. I don't suppose you guys can recommend a supplier? >sorry to be a pest after all this advice<

I'm using 6x 55w pc's.

Paul

 

[sales weasel]

For compact fluorescents, you could probably use one of these:
http://aquariumliquidators.com/MetalHalide.htm
These are pretty cheap and very reflective. I bought one of the 48" models.

 

[jay24k]

Yea I would just use those flat ones for PC's. Once you start hitting MH, you really should get the best imo. I plan on getting lumenarcs one of these days but my spider reflectors do very well. I have a tough time keeping low light corals happy and my sps grow very quick to the point I get aggrivated with the growth near another coral when my time is limited.