I am building a writing desk with a wide drawer (42"x19"x4 1/2") out of Indian rosewood, which is a fine hardwood. Instead of using solid wooden bottom, I am using ply supported by cross braces.

 

1/2" seems like over kill, 8mm Baltic birch seems like a good compromise.

 

On drawers of that size, I use 1/2" thick bottoms. If it's furniture, I usually make solid bottoms, but for kitchens, etc. I use baltic birch. If this is for clothing and such, a thinner bottom would do okay. 3/8" baltic birch would be perfect, but you could get away with 1/4" baltic birch. The reason I suggest baltic birch is because it is closer to a true 1/4" than most other hardwood ply, stronger, and it has minimal voids in it. In fact, I seldom come across any, and if so, they are very small.

Are you using slides or will it be wood on wood rails? Again, for expensive custom furniture, I do wood guides, but for pretty much everything else, I use side mount, full extension, steel ball bearing slides. (KV 8400)

 

It is maple on maple for slides. I don't like sticking mechanical things into what I make.

I think 3/8" Baltic birch ply sounds ideal. However, looking at my regular local suppliers, I do not see plywoods in 8mm or 3/8" size. Are these usually specialty order items?

I usually purchase my wood at either: Crosscut Hardwoods or Compton Lumber in Seattle, both of which have a very sizeable wood selection.

 

And i think I found the 3/8" directly after posting, it is listed in a separate section on the website.

 

1/4 inch would work clothes aren't that heavy, I have build hundreds of doors and only on a few have I gone thicker than 1/4 and never had a failure yet

 

In a chest of drawers, you and your wife might be the only ones to actually see the drawer bottoms. Still, on a fine piece of furniture, I would pay the extra to put in a nice looking drawer bottom. Regardless of your choice of wood, a 1/4" bottom will be very sufficient for your drawers. My personal choice for a good looking bottom is 1/4" Oak plywood with a natural clear finish.

 

Do you usually finish the entire interior of your drawers?

My last project was finished with Satin poly, which I liked and plan to use again for this project. I finished the inside of the drawers, which I wish I hadn't It doesn't really add anything from a look or feel perspective and it off gases and smells bad.

When you say clear natural finish, are you using a different finish for interior and exterior finish, or do you use a natural finish for the entire drawer/

 

I normally make a drawer with the bottom dado 1/2" up from the bottom of the box for 1/4" plywood. On larger drawers I put a solid wood rail or two underneath the bottom to support it. It also helps if you glue the drawer bottom in the dado.

 

I usually use 1/4" oak ply for my drawer bottoms, but then I/you need to look at usage as well. Even though I too would slot all four sides I think that if the drawer has a probability of holding heavy loads, then I would also laminate a 1 1/2" strip of the same ply to the bottom of the drawer bottom. I have found that this gives it the strength needed to hold what ever it needs to. Just remember to slot the sides accordingly so as not to interfere with the opening and closing of the drawer.

 

I think the 3/8 inch BB would be perfect. When we built the drawers for our kitchen, I used 1/2 inch pre-finished Birch plywood for the drawer bottoms. The drawer sides, front and back are 5/8 inch maple. I wanted the drawers to be sturdy for pots and pans (including cast iron). And, I used the 1/2 inch for the cabinet backs so I already had some on hand.

As for finish, I sprayed all the drawers with Parks Pro Crystal Clear Finish.
Hope this helps.
Mike

 

Two types of finish for drawer interiors.
A clear lacquer seals the wood on the bottom and sides and is fast drying.
A light coating of clear Watco oil finish is easy to apply and will bring out the grain of the wood.
Lacquer can be sprayed from a sprayer or a rattle can. The oil is rubbed on with a rag. Both good.

 

If the drawers are for clothing, I use no finish on the interiors, especially not OIL. It will get onto the clothes. If it's for kitchens or bathrooms, I use satin poly so that they are easy to clean.

 

I have been using an IKEA chest of drawers for about 25 years. The drawers are always full, yet no problems with the bottoms failing, which are simply hardboard (Masonite).

 

I wouldn't use anything less than 1/2 baltic birch or similar on the bottom. I have the same cabinet in oak I made 15 years ago. Dovetail drawers and wood drawer slides. I have waxed the wood slides twice since..

Thank goodness for the 1/2 bottom considering the clothes i have jambed in there....

 

3/8" Baltic Birch Ply it is.

Bottoms are now made and drawers are all dry fit. They feel really solid and I think the bottom thickness and material looks nice.

Not positive yet but I think I will go with no interior finish at all.

Now I get the fun job of surfacing everything before glue up.