Standard veneer on exterior door

[Joe Hendershott]

So I've read posts here and Woo Web about building doors and most of my questions have been answered. Still, I have a few and since I read that most guys here would advise against using thin veneer on exterior doors I wanted to address that idea again.

If it matters I build a fair amount of different furniture pieces and use veneer quite a bit. I generally use a 4x8 vacuum bag and get good results.

I'd like to build a 1 3/6" flush exterior door with a single sheet of some medium to high figured mahogany. My plan would be:

1. Use 2 sheets of 1/2" MDO and 1 2/8" MDO coated on all surfaces with West System epoxy, which I've always used, mostly on a couple of boats I've owned.

2. Run a band of solid mahogany around this (how wide should this be and is a 2 part plastic resin glue good for this?).

3. Adhere the veneer with epoxy and either use the bag or cover with plastic and press it with a substantial weight on a flat surface and a few layers of MDF under that weight.

4. Finish it up with 207 hardener and Sikkins finish.

I understand the thinness of the veneer will require that a good finish be maintained on the door. I plan to do a test on a smaller piece to see what it will look like but I normally use a danish oil and never stain. I am concerned that the epoxy will not make this veneer 'pop' enough for me. What work flow do you all use when you want a certain tint to wood that needs the epoxy?

Please point out the flaws in this plan to me.

[Jamie Buxton]

For adhering thin veneer, particularly over as large a surface as a door, the vacuum veneer press is much much better than mechanical weights. The vacuum gets the veneer pressed into place everywhere.

When you glue up that core, be sure to glue it up flat. Glue it up twisted, and you'll never untwist it.

Be very careful with the edgebanding on the core. If it is not exactly flush with the face, the step will telegraph through the thin veneer.

I don't understand your step 4. 207 is a catalyst for West Systems 105 epoxy. Sikkens is a whole product line. Which Sikkens product are you using? And why use an epoxy catalyst from West Systems with it?

[Joe Hendershott]

For adhering thin veneer, particularly over as large a surface as a door, the vacuum veneer press is much much better than mechanical weights. The vacuum gets the veneer pressed into place everywhere.

When you glue up that core, be sure to glue it up flat. Glue it up twisted, and you'll never untwist it.

Be very careful with the edgebanding on the core. If it is not exactly flush with the face, the step will telegraph through the thin veneer.

I don't understand your step 4. 207 is a catalyst for West Systems 105 epoxy. Sikkens is a whole product line. Which Sikkens product are you using? And why use an epoxy catalyst from West Systems with it?

Thank you for the reply. I can certainly use the vacuum bag, that is not an issue. I have a very flat low table 3" thick from MDF for gluing up other projects. I edgeband cabinet doors with hardwood and get them right by sanding and scraping. I don't like all the gloss from West epoxy and planned to use Cetol satin after it's cured a week or so. A flat finish would be ideal but haven't used any for exterior projects. This one will have a good bit of exposure.

Any benefit by using thin foam between that 1/2" MDO?

[Jamie Buxton]

....

Any benefit by using thin foam between that 1/2" MDO?

So in your original post, you meant to say that the core is two layer of 1/2" MDO, and the completed exterior door will be 1 5/8" thick? Then yes, you need to space the two sheets of MDO apart. I'd use strips of wood, not foam. You can size the strips exactly to get the completed door thickness you want, even when the actual thickness of the MDO is not .50". And a durable wood to wood glue bond is easy to make, whereas a long-term wood to foam bond -- well, I don't know.

BTW, interior doors are usually 1 3/8" thick, and exterior doors are usually 1 5/8" thick. Some exterior door hardware cannot fit on the thinner door.

[Joe Hendershott]

The original plan was 2 1/2 inch and 1 3/8 inch MDO, of course the foam would be between strips of wood. Making it 1 5/8 will require some solid wood planed to the correct thickness but should not be an issue. Thanks for pointing out my error in the thickness.

[Joe Hendershott]

All the information here is great but I would still like to hear from someone who does this about what thicknesses they use to lay it up. Around here I can get only 3/4, 1/2, and 3/8 MDO. What type of material do you use for the additional 1/8, or 1/4 inch that is needed? Am I right that strips of 1/8 inch solid material would not be an issue in movement? Three 1/2 inch or 2 3/4 inch?

[Jamie Buxton]

If you want to use MDO, and you want to make the door 1 5/8" thick, I'd use two sheets of 3/4" material. I'd cut solid-wood strips to use as spacers. The strips don't have to fill the gap entirely -- no thickness planing involved at all. They just need to space the two pieces of MDO apart. Putting them 6" on centers will work. Putting them closer together will also work. I'd probably glue and pin-nail the strips to the inside face of one sheet, then use your vacuum bag to glue the second sheet on. The MDO is probably less than 3/4" thick, so the spacers are like more than 1/8" thick. Be sure that the core is flat and not twisted while you're gluing the second sheet on. After the glue sets, you won't be able to remove the non-flatness.