Building with MDF question

[Craig D Peltier]

Hi , today I read an article about building cabinets with MDF that are going to be painted, that came out a few months ago in a mag called "Built Ins"
They reccommend using all (except draw carcasses) MDF 3/4 standard density. As far as the edge grain are concerned use drywall compound and then sand so paint wont soak into end grain much.
IM going to build a built in that needs to be painted a smooth white.Shelves on top an 4 draws below with pocket doors in center.Piece is 102 wide by 94 tall.Ive read to sand to scuff up a bit with either 220 or 150 and then seal it with a non water based sealer and then first coat of painy non water based preferrably shelac or oil based.
What do you think of using all MDF so the surfaces will remain the same for paint. I read that 28 inch should be max span for 3/4 mdf.I will not have any spans further than that. There will be several shelves, if I do use MDF for shelves is it a must to edge band with maybe 1/4 inch hardwood for stability? Like I said I think only two spans are 28 or 29 and the rest are like 16 inches.
I think the top and back I will use ply.You wont see the top after done since it will going to ceiling minus 1 inch, but yet it will be strong.
Im aware of MDF cracking with screws and the joints best suited for MDF.

Thanks again

PS Im going to add a pdf to this shortly.

[David DeCristoforo]

What is it that you want to know? If you can build this piece out of MDF? Or do you want someone to tell you it's an acceptable material for a project like this?

I am personally opposed to the use of MDF for anything with the possible exception of using it for "one time" jigs that I just need to bang together cheaply and will probably never use again.

So my answer would be "Yes, you can....But......"

I think you would have a vastly better product if you were to use a decent quality birch ply for the casework and either birch or hard maple for the faces. These materials will take paint just as well as MDF (and probably require less prep) and you will end up a piece of "real" woodwork.....

The above represents MMHO and is not intended in any way to disrespect those who would disagree.....

[Chris Barton]

MDF will work just fine but, don't expect it to be a replacement for wood. MDF is basically cardboard and as you suggest it must be well sealed before painting. There are many ways to do this including the ever coating with PVA thinned with water, drywall compound, old latex paint, etc.

[James Phillips]

MDF is very flat and true. It is easy to work with, btu heavy. I never use it, because it is not as durable as other options, and the dust is horrible for you. I have great dust collection and still would not use it except in rare cases

[Wes Bischel]

Craig,
I've tried the drywall compound process, and I have to say using shellac (dewaxed) was much faster and produced a harder, crisper profiles. The shellac wicks in and can be brushed on as quickly as is is sucked up. The only thing necessary afterward is sanding off the fuzz which is hardened by the shellac. The edges/profiles then take paint as well as the faces.

FWIW,
Wes

[Art Mann]

I built some shop cabinets a couple of years ago. The boxes were MDF and the face frames were made of pine. The backs were 1/4" plywood. The tops were made from 1-3/4" prefab bench tops I bought surplus for cheap. There were no exposed edges to paint. The material is plenty strong if you design it right. I painted the flat surfaces with latex primer. I sanded them lightly and then painted them with a latex top coat. The final finish turned out very smooth. There is no need to use any kind of oil based sealant.

Having said all that, I would not use MDF again. The stuff is way too messy to deal with. It is just about impossible to keep the dust from getting everywhere, even with a good dust collection system. Do yourself a favor and use plywood instead. It is worth the extra cost.

[Craig D Peltier]

What is it that you want to know? If you can build this piece out of MDF? Or do you want someone to tell you it's an acceptable material for a project like this?

I am personally opposed to the use of MDF for anything with the possible exception of using it for "one time" jigs that I just need to bang together cheaply and will probably never use again.

So my answer would be "Yes, you can....But......"

I think you would have a vastly better product if you were to use a decent quality birch ply for the casework and either birch or hard maple for the faces. These materials will take paint just as well as MDF (and probably require less prep) and you will end up a piece of "real" woodwork.....

The above represents MMHO and is not intended in any way to disrespect those who would disagree.....

Cost isnt my worry. Getting a smooth paint job is my worry. So I inquired about MDF since I had just read the article.My budget planned for 3/4 american birch ply.
Thanks

[Craig D Peltier]

Okay if I use Birch ply and the shelves have exposed edges as well as the desk top what shall I do to cover them up so there smooth and when you paint them they dont look like two pieces if I hardwood edge banded them.
Can I use just veneer tape for that part?

This piece should look modern in design. The draws will be flat faced , im going to try an talk her into 1/2 inch overlay draws but she might want flush with blumotion slides.

See attached JPG of my rough drawing.

Thanks

SAVE0065.JPG

[Brad Counts]

I use MDF and prefer it over just about anything else for surfaces that will be painted for most applications. I like it because it is stable and takes paint like nothing else. The downside for me is the dust! I have remedied the situation somewhat by adding an overarm blade guard with dust collection on my table saw to use in addition to the regular 4" port in the base. I also have a vertical panel saw that I can wheel outside to rip up large quantities of sheets.

I have had great success building rail & stile raised panel wainscoting entirely out of MDF. About the only place I wouldn't use it is for cabinet carcasses and rails & stiles on cabinet doors - I will normally use poplar for this and use the MDF for the raised panels.

[Jon Dieterlen]

I use 3/4 bir ply for paint grade. MDF in my opinion is not strong enough for a cabinet the size you have pictured. I use MDF for door panels only as it paints better than solid wood. I mix wood glue and water 50/50 and brush on any machined edges, let dry then sand w/220 paper. For face frames and edgebanding, hard maple would be the best. Soft maple would be second best then poplar comes in third. It depends on what the customer wants to spend. If you can spray, a couple of coats of M.L. Cambell clawlock primer will give you very good surface for that glass smooth top coat. Always double coat the machined MDF edges.

Also always use double refined MDF. Any reputable supplier should know what you're talking about.

Jon

[David DeCristoforo]

Veneer tape will work fine as long as it's glued down properly. I like to use a T&G edging which is more work but very solid. I make the edging a "tee" shape with a "face" thickness of about 3/16" and the "tounge" around 3/8" deep. I glue the pieces up in pairs so that the plywood pieces act as cauls with the edging "face to face". Of course, on "lower end" jobs, I just use edge tape.

[Brad Naylor]

I do a lot of painted work and use nothing but MDF. Carcasses, face frames, door frames, panels, drawers, everything! It is by far the best material for painted furniture - I wouldn't even think about using anything else - even for high-end work.

However, I don't use regular MDF - the fluffy stuff. I exclusively use moisture resistant MDF. In Europe this is dyed a green colour to identify it - I don't know about the States. The advantage of this is that it's higher resin content makes for much harder and crisper edges and it takes a finish beautifully. A couple of coats of AC primer and then a top coat is all it needs, even on the edges.

Why anyone would want to use real wood or ply and then paint it is a mystery to me, and to most other cabinet makers this side of the pond.

Cheers
Brad

[Bert Johansen]

If you do choose to use MDF, which should be OK for this project, you don't need to "scuff" sand. Just prime with Kilz (white shellac) and topcoat.

Another option might be melamine. No painting, and very sturdy. Just a thought.

[Rob Wright]

I have used MDF for painted furniture. The dust is annoying, but I get over it. I have sealed the ends with BIN (White Shellac) and painted with Latex paints.

I seem to always worry about sag and I salways place a piece of hard wood to the front of the shelf when using MDF for shelves greater than 24". This may not work for you seeing that you have stated that SWMBO wants a modern look, and your sketch clearly shows no face frames to add that rigidity. I don't know about the 100" width though, MDF in my area only comes in 97"x47" pieces - something to think about?

-Rob

[Frederick Rowe]

Craig- I've used MDF on some early projects similar (but smaller) to yours. I tried the drywall compound to seal the edges and urge you to try something different such as thinned white glue, etc. . . Sanding the compound was a huge mess. MDF takes paint fine with a primer, nothing fancy required.

If you are not wed to using MDF, consider MDO, it has a paper face, excellent for taking paint, and is plywood beneath. You'll get the zero prep face for paint, the greater strength of plywood, and none of the brown talc dust from cutting the MDF.

Good luck, post photos when done!