mdf boards for layout... is it safe ?

[alain10025]

Hi,

 

Over the past two years, I built a couple of layouts. I used MDF panels (usually 1/8 inch or 1/4 inch thick) below a cork layer where I run my trains. I found these MDF boards to be easy to handle.

 

I recently discovered that MDF boards contain toxic elements and specific precautions must be taken when cutting them for instance. 

 

 

Do you have any thoughts on the use of this material ? Do you think it is safe to use it as a support (with no primer, no coating) for a layout ?

 

Thank you !

 

Alan

 

[cteno4]

Alan, 

 

Good, dense mdf can be a very solid material to use for layout support. It has a lot of resin in it and that tends to repel humidity more than cheaper plywood does. But it does require slightly different construction techniques. MDF does not take screws so well, you need to be a bit more exacting in drilling holes and careful torquing of the screws to not strip out the wood with the screw threads. The screw joints are not as robust as they are in cabinet ply or Baltic birch ply. But things like biscuit joints can work well with MDF. MDF is really dense and heavy though, which for support structures usually isn’t an issue as long as you are not moving them around all the time. It’s not so pretty of a wood and requires a couple coats of paint to get a smooth coat. The corners do ding a bit easier than hardwood plywoods do. This is why it’s covered with a plastic veneer a lot.

 

The issue with cutting MDF is primarily that it’s a fine sawdust combined with a lot of resin glue/binder. When you saw this you end up with very fine powdered sawdust that has a lot of resin in it. Regular plywoods have similar resin/glues in them, but a lot less and the sawdust created is not near as fine. The finer the dust the more it can get into your lungs and sinuses to cause irritation and some toxicity. That being said when I work I the shop I now have a room air dust handler on, a dust handler attached to the tool, and a mask or positive air shield over my face. Even pure pieces of wood the saw dust can be a bad irritant that can eventually cause reduced lung performance (it can form scar tissue replacing good lung tissue). Also lignins in the wood (the natural binder in wood that holds the cellulose fibers together) can be a bit toxic, irritating, and cause allergies for some. So this is a general issue when doing wood working, just more extreme with MDF.

 

Personally I’ve never really like working with MDF due to dealing with the sawdust, weight, and structural connections. It’s also gotten harder and more expensive to find really good MDF. it’s looks as well get me, it just does not look like wood and I don’t like paint as a finish on wood much. A lot of the train stuff I work on is moved around a lot so the weight if MDF makes it out for me and in making things lighter joint surface area and size goes down and that is more of a weakness with MDF

 

My big material of choice for most all woodworking I do in the last decade or so has been 7-11 ply Baltic birch plywood. It’s a big more expensive but really has the best of all types of wood materials. It’s a plywood so you get the crossed grain layer structural support for stiffness. It’s a medium density wood, got some hardness to it but not too hard. The skin layers are thick (like 1.5-2mm) and not paper thin like most plywood snow. The edge corners also hold up well and the edge grain actually looks nice and you can keep it as a feature and not have to veneer them. I cut it into strips and put them thru the joiner and planer and get really nice dimensional lumber that keeps truer with humidity than softwood dimensional lumber and actually is cheaper in terms of the quality of the resulting lumber as cheap dimensional lumber is pretty hideous these days and nice stuff is really expensive.
 

I think as long as you are careful with good dust collection as you work with MDF and vacuum it all off well before bringing into the house you are fine.

 

If you decide to use MDF search around YouTube, tons of videos there on working with MDF and best joinery to use.

 

cheers,

 

jeff

[alain10025]

Jeff,

 

Thank you very much, this is very useful. I did identify the main issue of MDF was finer dust and I really appreciate your recommendation for Baltic birch plywood. 

 

I have been looking around the internet and found many use of MDF panels for small DIY procjects (such as a support for displaying various items in kids bedrooms) and I am wondering if the dust from these panels could not be sprayed just by hand contact or friction with other objects. At least for the MDF panels I have been using, I feel this dust or light powder quickly shows up on your hands (hopefully with gloves !), even without cutting the panel with a saw... 

 

The reason for this whole investigation on my side is that I noticed some railroad tracks were getting dirty very easily on my layout (some locomotives would slow down in a strange fashion, like the power is difficult to get even though the front lights are not flashing). It so happens that this track is right below the edge of a MDF panel that I cut with a saw (edge of some kind of cliff right above the track). My impression is that minor vibrations on the layout (that happen due to the fact that I am currently building the layout and drilling here and there for wiring purposes) lead to MDF dust to fall from the panel to the track... I am thinking to tape the edge of these panels to prevent dust going everywhere...

 

Thank you again !

 

Alan

[Junech]

I think that might be your MDF board or the random dust from working on the layout. We always work with it to build different things for the layouts. we never had dust coming from them after they were cleaned once (we vacuum and then use damp paper towel). We even use HDF boards for our transport and storage units as dust protection. It could simply be that the boards collected some dust over time and together with all the dust you produce while working on the layout it leads to that result.

 

For the frame of a layout, we opt for birch plywood as well. We use a 16mm type that is called "Tischlerplatte" here. I don't know what it is called in English but searching on Google would show it up in the images. The main difference is that instead of the many layers, it only has 3 (or 5 if you put on decorative layers on the outside). 2 are skin layers and the middle one is higher-quality lumber. This site has a nice image of it (Link).

The reason why we use this one is that it is lighter compared to the 10-12mm regular plywood we would otherwise use while having the same strength.

 

Junech

[cteno4]

Alan,

 

yes untreated MDF cut edges probably keep shedding fine dust over time. But it would need some air circulation from under the layout to fly it up on top of the layout. One solution is just to add a layer of paint or varnish to the MDF, especially to the cut edges to stop dust from coming off. I would think the face surfaces would not shed much.
 

It’s best to have a hepa air filtration system on in your train room little free standing model to mainly get the dust) and decent hvac filter in place to keep dust down on the layout. They have really helped keep dust down in our house and we live in a thick forest that drops a ton of pollen and fine matter. Layouts are magnets for dust! Also just putting a thin plastic sheet over the layout if not being used for a good chunk of time. Using a vacuum car also helps. You can also buy a micro hose attachment (I got a longer piece of hose for it from Home Depot) for your vacuum cleaner or run down your track and other vacuumable places to clean out dust well. I put a piece of nylon stockings or mesh in one of the vacuum joints to catch any stray bits if scenery or parts that could accidentally get sucked up. There are also now a scad of small handheld rechargeable vacuums for $10-30 with all sorts of attachments for small places. I picked one up last year and they suck pretty well and have a pretty fine filter on them and you can see and easily retrieve any parts sucked up. For structures I use makeup brushes to knock off dust with the vacuum end blowing next to where I’m brushing to suck up the knocked off dust. On scenery you are kind of screwed as vacuuming will just suck the scenery up, so it’s best to keep the room dust free for that. 

 

For the tracks, some of that could be dust and some could be oxidation issue as well. Get some low dielectric contact cleaner to go over your tracks, as the track gets cleaned and the cleaner displaces water in the micro pores in the track you get less microarcing with leaves the black gunk on track and I would bet also has dust sticking abilities. It’s been amazing over the last couple of years how our club track has needed way less cleaning.

 

Personally, MDF gives nothing of an advantage other than price, but in looking around the big mix stores now look to only stock the cheaper, larger particle, particle boards. Particle boards anre just not worth the trouble to use in just about anything, they are the worst of all worlds combined. Even the MDF I’ve seen in the last 5 years or so does not look as fine structures as the old MDF which looks like what is now HDF. Wood in general has gone down in quality, with most of the usual levels dropping a notch as compared to a decade ago for a number of reasons.

 

Unless you are building something huge I would just recommend going to birch cabinet ply like Junech suggests. Here in the states 3/4” birch cabinetry ply is 5 equally thick core layers and two very thin skins (you can sand right thru them with 120 sandpaper on a palm sander if you are not careful) of birch on the outside. This is the stuff most kitchen cabinet structures are built from. Usually I’ve found Baltic birch ply locally for only 25% more than big box birch cabinet ply (and theirs is cheaper and less quality than real cabinet birch ply). 
 

cheers

 

jeff

[chadbag]

The only thing MDF is useful for to me is for guitar templates for the router...     LOL

 

I'd be interested to see how you're using it.       I did buy some 1/4" "ply" that was a thin veneer of wood on both sides of a sheet of MDF.  I think it was Alder.   I don't remember -- its been a few weeks.

 

 

 

 

[Dani]

Hello,

 

I'm not expert in this matter, but I always followed the recommendation of different carpenters who told me to use "okume marine phenolic plywood lining". I just made a literal translation, I'm not sure if this is the correct name in English. In Spanish is "tablero contrachapado fenólico marino de Okume".

 

http://www.mourikis.gr/plywood/content/153/okoume-marine-plywood-/eng

 

It resists water (it is used in marine applications), light, easy to cut and screw, non toxic and some of my first modules are 20 years old and the wood has no signs of aging.

 

But again, I'm not an expert. I just followed the advice of wood workers.

 

 

[cteno4]

Yes marine grade ply is the ultimate! It can have more layers of ply than Baltic birch (and way more than standard plywoods), a more water resistant resin/glue, and usually the best quality wood you can get for the plys. The other nice thing about it is you can also get it in some other hardwoods like Okoume, teak, mahogany, etc. Also the ply pattern on the edge can really look pretty. Okoume Is one of the plys used a lot in boat hulls as it’s not as dense and fairly water resistant.
 

Downside is it’s usually pretty expensive (about the most expensive you can buy and over 2-3x the Baltic birch price last I looked) and it is hard to find (so prices worse as less competition). I’ve only use it only in specific furniture projects due to the price and availability.

 

Marine plys are generally way overkill for doing most all model train stuff woodworking.

 

jeff