I’m about to start my next project – a set of built-in bookcases for my master bed room. I’ve built a set like this before and I’m wondering what the best material would be to use. Previously I’ve used some pretty nice plywood – after a little sanding it took paint well and it seems very strong. I’ve also used MDF – very smooth and more consistent thickness than the plywood. Cost difference seems minimal. Can anyone think of benefits of one over the other before I decide which way to go?

In my amateur opinion, MDF would have nicer looking edges, but those same edges may be prone to denting or breaking off at the corners.

I was facing the same dilemma recently for a project, and look forward to more experienced feedback.

IMHO, I agree with Shane. MDF edges are sharp, but can be broken/dented easily. I've used MDF in projects and covered the edges with veneer. So, I generally use plywood and veeners. If the cost difference is minimal, go with plywood.

Howard

I forgot to mention, for the bookcases i'll build a face frame out of poplar so there wouldn't really be any MDF edges to easily damage.

In that case, I think I would choose MDF over plywood, if for no other reason than not having to sand, sand, sand to get the same fine, smooth finish before painting, and the lack of knots, patches, etc. with that can be present on plywood.

However, you may have to use different joints than you would with plywood, I'd do a little research on that.

I'm not sure what you are planning these shelves for, but if there will be any weight loaded over time, I would go with plywood. Much stronger, and won't sag as much/fast as MDF.

Since you are going a faceframe, using plywood would seem like a no brainer.

in a previous project with MDF I made Dado joints, glue, screws (predrill holes). solid as a rock.

mdf has less structural integrity than plywood and it is much more susceptible to damage from water than plywood. in all the projects "Nahm" built on NYW, mdf was used primarily for inset door panels. i'd use plywood, since the cost differential is minimal and edges are being face framed.

I loath and despise MDF. The stuff responds to humidity in the air by swelling and falling apart.

The inner core of MDF is soft and not glued together very well at all . The outer skins are glued and compressed and they are the strength of the stuff. Edges of cut MDF don't take glue well because it's so crumbly so adhering edge strips to cover the stuff up is dicy.

Good American made ply (not the unbelievably bad garbage they sell at Home Depot and Lowes) that you get form a good lumber yard wiull do you nicely. Baltic Birch is the best choice but few places carry the real McCoy so you'll have to settle for "VOID FREE" birch ply. Be sure to say you want void free.



Years ago (like 20 years ago) the BORG was OK for ply but they have gotten so very bad lately applying downward pressure on the prices they will pay their suppliers forcing the makers to use substandard lumber and less and less glue. The people the BORG don't apply engineering standards to the lumber materials so the makers can just keep cutting quality.
Don't buy ply at the Home Depot or Lowes.

Good points, Cliff. I have used the Aurucoply from Menards with great success on many projects. It also has a thick outer layer, and they use exterior grade glue on it as well.

MDF weighs significantly more than plywood. It doesn't take screws as well either. Where this becomes a factor is in the size of the units. MDF can collapse under it's weight when moving it into position. Again, depending on size and weight.
MDF, if accidentally wet can bloat kinda like oatmeal. MDF shelves will sag much more.
If it were me, I would much rather use plywood. As for the edges of plywood shelves.............take a 3/4" board of poplar. Round-over one edge on both top and bottom. Go to table saw and slice this edge off at 1/4" to 3/8" thick and glue this strip to the edge of the plywood shelves. As for edges to be painted, fill and smooth with bondo.

I use MDF for some things, but I absolutely despise the stuff; because of the damned dust it creates, which, despite my dust collection and filtration systems, still manages to irritate my eyes and get into everything. I hate the stuff. However, I am currently building a tablesaw jig from it. Glad I'm finished with the power tool portion of the project. Damned dust.

+!
How could I have not thought of that.

BTW, do you have a sailboat?

You could also go with Ultra Core. It's a plywood core with mdf skin. Best of both worlds.

http://packardforestproducts.com/pro....vhuCzes7.dpbs

Yes I do, a Catalina 36 on the northern Chesapeake Bay Eastern Shore (near Chestertown). Gives me additional woodworking challenges; things in your house are rarely square; things on your boat never have straight lines

For casework to be painted, I will only use veneer core ply, paint grade Maple. Light, strong and not too expensive.

For some projects MDF works out well. For interior cabinetry to be painted, Maple plywood would have to be very select IMO. Most Maple plywood has fair faces. It would be on a scrutinized selection basis. Baltic Birch, or Appleply makes for good paintable surfaces, and for better joinery.





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I had a Catalina 25 and then a 30. We loved the 30 but lost it in Hurricane Katrina. We now have an older Allied 39 ketch and a 36 Mainship Aft Cabin. Lots of boat projects. I posted some of my completed projects on here. I need to make a new website and show the construction details and the methods used for fitting into non-straight and non-flat surfaces.

I'm with you. I friggin hate MDF because it's so nasty to work with. I also think it costs about twice as much as it should. Seriously, I don't understand how it's even close in price to real plywood considering what it's made of

Condolences on loss of your boat. I met a couple that lost their boat in Sandy last fall and were buying one for sale at my marina.
I had a C30 for 9 years and also loved it. Traded for the C36. Would love to see your projects if you have a link.

On topic, NEVER use MDF or even tempered hardboard on a boat. Despite the fact that some of my cabinets have it; I've replaced some with plywood when it warped or disintegrated. MDF doesn't seem to even like high humidity much.