Mdf?

[Diesel Dork]

I'm trying to decide whether to cover my stand with plywood or MDF. In the end it is going to be painted in and out so the wood grain doesn't really matter. I'm just concern about whether the MDF can stand up. Has anyone used it?

[MayoBoy]

I wouldn't use MDF. The least little bit of water and it starts expanding and is ruined. There are some applications where MDF works great but a tank stand isn't one of them.

[Douglas LEHMAN]

Hello
MDF would be my last choice!

[Rendos]

Ditto. I wouldn't recommend using MDF around water.

[BigJPDC]

I am at this point in my stand construction right now, and already have the piece of MDF cut for the top, not wanting to waste a piece of oak ply where it will never be seen. I am glad I read this because it would indeed be crazy to put MDF under the tank, where the most water will probably contact it.

It would be easy to replace it with 3/4 ply instead, but what about cutting and fitting a sheet of pond liner over it before the tank? Would it provide protection and cusion for the tank, or is that a bad idea? I would think that even plywood should be primed and sealed as well here.

jp

[cres]

You can "seal" it or protect it, as you like, but, short of epoxy, most coatings won't totally seal the surface.

Some moisture will get through and you are putting it in a high humidity setting. MDF swells and gets soft when moist. Plywood and certain solid woods tolerate high humidity better.

[BigJPDC]

Sounds like good advice Cres - thanks!

jp

[drew22to375]

What is MDF?

[Highlander]

Originally posted by drew22to375
What is MDF?

http://www.design-technology.org/mdf.htm

[TAB]

Meduim Density Fiber-- large saw dust peices and a "glue"

[BigJPDC]

MDF is cheap, spews forth tons of toxic dust when cut with power tools, and is great for pieces that will be used in dry environments where finish (or appearance) isn't important. In my workshop I have some shelves, jigs and tabletops made out of MDF.

jp

[Atomahawk]

Poor workmanship and finish with plywood will lead to rot and it won't take that long if you dont know how to water proof and finish wood. It is more tolerant to water but end joints are harder to seal since they do chip a lot on the edges. MDF is great material for a few reasons. 1) its ridgid and strong. 2) it's surfaces are true flat and contains no imperfections unless you damage it yourself. The downside MDF has a nasty habit of swelling if water is absorbed on the ends (just like plywood would) , but is very easy to seal and finish since it's surfaces are so flat. Sealing and painting it properly will give you as good if not nicer results than plywood (especially cheap ply). It's all about workmanship and skill, both have their advantages. If your not to meticulous plywood is a better material.

As for safety concerns MDF gets a bad rap simply out of people thinking because how it’s made it spews out chemicals like there’s no tomorrow. This is pure ignorance. Yes it do’s have formaldehyde and other substances used to bind the particles, and yes when cutting it do’s create more dust that is finer than normal wood and others dust. But if your cutting or working MDF and plywood or oak etc. in a closed shop with no ventilation on a constant basis with no dust mask on, you’re a moron and shouldn’t be working with any power tools to begin with. Common safety is wear eye protection and dust mask, no loose clothing and use push sticks and guards whenever you cut.

Just a short story to prove my safety point. A friend of mine was cutting ¼ plexiglass on a table saw without the guard. Needless to say I warned him , but “ its to long to put it on just for a 1inch cut “. He turned white when the offcut flew 15 feet and imbedded itself in the opposing wall. I had the permission to call him a moron after that!

[LiquidShaneo]

MDF is cheap, spews forth tons of toxic dust when cut with power tools,

'Toxic' dust? What's toxic in it? It's comprised of cellulose wood fibers and a bit of urea-formaldehyde (UF) binder and the formaldehyde is completely crosslinked into the board. It may offgas a bit, but it's not considered 'toxic' by any sense of the word. If it were toxic I'd be dead by now considering and the EPA would have halted its use. I work in a HUGE furniture plant that primarily uses MDF and particleboard.

Shane

[BigJPDC]

Oh goodness. I had no idea that MDF had such a fan base.
I have used it plenty myself, and am also alive. I really do not have any ill will towards MDF, and I even said that I use it all the time for shop projects and shelves. I thought I read somewhere that the dust was harmful and I always get masked up when I'm using it because it makes such a mess, even with dust collection and filtering running.

A search on 'MDF' and 'toxic' brought up a few links - this one is amusing because it's more about unions than the MDF.

http://www.hazards.org/unioneffect/articles.htm

In October, HSE was accused of protecting the profits of medium density fibreboard (MDF) makers and not the health of workers exposed to MDF's toxic dust.

The criticism, from the Transport and General Workers' Union, followed an HSE press statement that "it is HSE's view that any health risks arising from the use of MDF at work can and should be effectively controlled by compliance with the requirements of the Control of Substances Hazardous to Health (COSHH) Regulations 1994 - there is no need for a ban on MDF."

HSE failed to refer to its own evidence showing few employers observe or even know about their COSHH duties.

HSE's statement came after national TV and press stories linked MDF's chemical constituents to lung cancer, allergies and other health problems.

HSE said that it is hardwood and not the softwood that is found in MDF that is classified as cancer-causing in the UK. Formaldehyde released by the bonding resin, MDF's other constituent, was an irritant, it said.

And then this one.

http://www.workershealth.com.au/facts023.html

Medium Density Fibre Boards (MDF)
MDF is widely used in the joinery and furniture industry as well as in building and housing construction. The major constituents of MDF particle boards are pulverized softwood and urea-formaldehyde resin, both of which are recognized as potential health hazards in the working environment. MDF produces very fine dust during processing and the dust particles act as a carrier of absorbed formaldehyde to the lower airways of lungs.

Wood dust and formaldehyde together have been reported to cause respiratory irritation with symptoms of dryness of throat, rhinitis and eye irritation as well as occupational skin disease. Protective measures for wood dust exposure should be followed when MDF is used.

jp

[ashkeenon]

hi

I have used MDF to build a fish tank unit and it has been up for over a year & i still havent got around to coating it with sealer and have spilt water many times over it with weekly water changes and so far no swelling its not as bad as every one thinks.

I personally think MDf is great structurally and a good work surface for applying finishes where your not worried about wood grain. But is recomended to use suitable waterproofing, and also watch out for the small dust particles bad for fibrosis of the lungs.

I personally would use mdf on a tank stand as long as it is properly protected like any other wood.

Ash

[crazyfish]

Both of my stands and canopies are made of mdf and finished with a good oil based paint. I have had water sitting on top of these surfaces for long lengths of time and no problems. The only way it will swell is if you get it on the ends and it has time to soak in otherwise no problems.

[Sm0kin]

i do have to agree MDF is in my opinion better then plywood. I uses it to build my speaker box for my truck. The shelves in my video store and just about everything else. On places where i needed some water resistance i paint the mdf the color i need than do a couple of coats of clear urethane. nice glossy look. and not to expensive.

[jaden1]

If you like all of the benefits of mdf but are worried about swelling due to moisture issues. You can get ahold of a product called Extira. It is an MDF type product made for high moisture applications. I have built several stands with it and have been using to make exterior trim and woodwork for a couple of years now. Great product. One small setback compared to MDF though; you need to sand milled edges more than reg. MDF. This is due to the manufacturing process. MDF is pressed by 2 heated plates and extira is pressed by 2 plates in a microwave (sort of). Anyways both can be used but if you go with MDF spend the extra bucks on finishing. Your priming here is essential to the finished quality of the product.
Good luck
Jason

[240-Reefer]

If you want the mdf and not plywood go with MDO. "O" meaning outdoor. they use waterproof glue. I would use the plywood.

[MayoBoy]

MDO is Medium Densidy Overlay. It's plywood that's overlayed with kraftpaper. Mostly used for signs, etc. It would probably be overkill for a stand though. Regular old CDX would work just as well and it's cheaper (but uglier).

[Donw]

Originally posted by 240-Reefer
If you want the mdf and not plywood go with MDO. "O" meaning outdoor. they use waterproof glue. I would use the plywood.

Just water proof plywood with a wood fiber and resin overlay. Most commonly used by sign makers and people with lots of spare cash.

Don

[bassnman11]

I put a sheet of 1/8 acrylic from Home Depot on top of my stands. They are oak with a poly finish, but better safe than sorry. If you prime and paint the MDF you should have no problem. When exposed to small amounts of water, MDF does not swell like old fashion particle board.