What type of wood is best for a canopy?

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I'm planning to build a canopy for my 200G Aquarium. I will be sealing it with some sort of polyurethane to minimize warping, but still I'd figure some woods would be better than other. I also want to paint it black and would like to minimize sanding if possible.

Someone suggested furniture grade plywood or poplar. Can I get some insight on this please?

One more thing... how snug should the canopy fit? The tank is 84.5" from bracing to bracing, the wood is 1" thick, I was thinking I would cut the front panel 86.5" in length but that would make a very tight squeeze. Should I maybe go a little longer?

Thanks in Advance,
Dave
 
MDF, and depends where you want the outside of the hood to sit.
I plan to have a 1/4" gap or less inbetween the glass and the hood.
 
Plywood resists warping better than any solid lumber. I'd suggest birch plywood. They sell it in thicknesses of 1/4 - 3/4 inch at Home Depot. It's got two nice, smooth sides - a quick sanding, and it's ready for paint or stain.
Apply at least three coats of polyurethane for maximum water resistance, and be especially sure to completely coat the plywood edges.

I'd plan for at least a 1/8 inch gap between the tank frame and the canopy on all sides. This will allow for some wood 'movement' due to the humid environment.

If you can, post some pics of your project during construction.
 
i would stay away from MDF... it absorbs moisture really well.

i used poplar lumber and skinned it with 1/4 oak plywood.
if you dont want to use a lumber, then use the birch plywood suggested above. plywood will give you good dimensional stability.
~mike
 
If they're just going to paint it there's no sense in spending the money to veneer or investing in hard woods.

MDF can be problematic if it's not sealed properly. It is horribly bad at absorbing moisture. However, I made a canopy for a 20 gallon tank that I had and never had any problems with warping as it was well sealed inside and out.
 
I built one of solid pine about 28 years ago, and it has held up very well. It is well sealed, and that is the key. When I build the next one I will seal all interior joints with caulking of some sort.
 
I think I might try out MDF and seal each piece individually before assembly with varnish, then seal the joints with some sort of caulking, liquid nails or something. I'll support the whole thing with angle braces and do a front hinge so I can use the entire top area for lighting.

I'll post some pics of my progress as I go. Thanks everybody!
 
I would not use MDF, not only because of the water absorption issue but also the chemical glues. It will not stand up anywhere near as long as you want it to. I can shop grade plywood here, 3/4 inch for $12 per 4'x8' sheet. Any warping from heat and cold and you will have water absorption and MDF will not last long.

If I ever build my own, I will not use plywood nor MDF, I will use alder or pine.
 
I would not use MDF, not only because of the water absorption issue but also the chemical glues. It will not stand up anywhere near as long as you want it to

MDF will last if you look after it. Much like anything really.
I wonder why 90% of kitchens, bathroom and laundry vanities are built with mdf and chipboard?
I will still be using mdf, but unlike kitchens etc, mine will be totally sealed.
Particularly the edges as this is the bit you dont want to get wet.
 
you suppose to seal off the splash with silicone and they seal up the edges pretty good with a glue on the counter tops.. and yea, its MDF..

I would say MDF is fine.. (I would go with whatever I had hany or whatever is cheaper but thats just me)
 
If you seal the hood up properly you can use anything. However, MDFs structures doesnt lend well to sealing, it will just keep soaking up the sealer and never develop an outer layer. Plywood seals pretty well you just have to make sure to fill in the gaps in the ends. Easiest to work with will be solid lumber. Cut the pieces, seal them before assembling, assemble, and then seal again. Or for a little different look you can fiberglass it after fairing the wood, and if you want to get rid of the weave lines bondo it, and paint it.

It might also be a good idea to seal off the inside of the hood by placing a sheet of plexiglass in the bottom ( cut a groove into it to sit in).
 
MDF is also really, really heavy....something to think about if you have to remove the canopy for maintenance, replacing light bulbs, etc. I did a mosaic on mdf and it was a royal pain to seal enough so that I could grout over it. It gets used for kitchens and bathrooms because it is cheap, sturdy and gets covered by something else for water protection and looks, but watch out if it gets wet!

Polyurethane is great for sealing, but if you really want to go hard core, particularly on plywood, seal all the pieces with epoxy, then assemble and paint. Boats are built this way, and they get the worst water and UV exposure you could imagine! Sheet ply boats sealed with epoxy will last as long as fiberglass with proper maintenance.
 
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