Sunday, November 18, 2012

Tambour Glue

40 years ago I was the first one in San Diego to sell a roll top desk for $2500.  It was the period of Golden Oak and everyone was furnishing their houses with oak furniture.  I would drive back to Nebraska and buy a truck load.  I remember buying a dozen oak cabinet treadle sewing machines (with the machines working), numerous oak tables, both square and round, with lots of leaves to match, countless press back oak chairs, hutches and desks.  I sold them as soon as I unloaded the truck.

I was always looking for exceptional desks, and one day in Lincoln I saw this monster desk.  It was quarter sawn oak, with what looked like hundreds of small interior drawers, all different.  The outside was beautifully paneled with raised panels on all sides, even underneath where you couldn't see them.  It also had a matching chair.  This desk was so large that I could lay down on top of it and close the roll over my head.

In recent years I haven't seen a desk sell for much more than lumber, as they just are not popular any more.  Then, suddenly, three show up in my shop for repairs.  One of them was on its way to the dump and the handyman had the good sense to drive out of his way and drop it off at my shop.  Free.  The second desk was in pieces at a garage sale, and, when they couldn't sell it, they called me to see if I wanted to pick it up.  Free.  The third was a desk which was on loan to the local historic house, where it was stored in the attic office of the caretaker.  I was asked to provide a proposal for repairing this desk in 2010 and forgot about it.  Last week they called and said it had to be out by that day at 11:30.  At least that one will make me some money.

All of these desks have one problem in common:  The tambour roll is messed up.

What people don't know about a tambour desk, like a roll top, is that it needs to be used often.  When the roll is opened and closed regularly the canvas bends at each strip and flexes evenly.  When the roll is open and left in that position for a long time, there is a stress on one strip only where the sharp bend in the roll occurs at the back of the inside rack of drawers.  That one strip will then probably tear the canvas the next time it is moved.

People often try to repair these rolls with contact cement, not knowing what glue to use.  The results are predictable.

This is a typical case where the repair was made with strips of canvas glued to the old canvas with contact glue.  It did not work.

I have a system to reglue the canvas backing on tambour rolls and it works every time.  In fact, my research proves that the original makers of these tambours used protein glues modified with urea to extend the open time and provide more flexibility then hot hide glue.  That is why I find Old Brown Glue to be not only the perfect glue for this repair, but as close as possible to the original method as you can get.

I place a sheet of 3/4" plywood on the bench and clamp some strips of wood around the outside of the strips.  Make sure you are at 90 degrees so the roll slides nicely in the cabinet.  Use some weights to hold down the center of the strips and clamp some extra wood on each edge to hold them in place.

Now you can use a belt sander, with a coarse belt, to remove all the glue and canvas from the backs of the strips.  Make sure they are clean, sanding across the grain.

Take some Old Brown Glue and warm it up in a water bath.  Pour it on the strips and use a short hair paint roller to spread it evenly around.

It should look like this:

Get some heavy canvas, like you would use for a sail boat.  Cut a piece to fit the area and pour on the glue.

Spread it around evenly with the roller.

Now place the canvas, glue side down, on the surface of the tambours.  Use your hands and a veneer hammer or other roller to even out the canvas, pushing the excess glue out to the sides.  Clean up the excess with paper towels and a wet sponge, using cold water.

In simple terms, you are using the basic hammer veneering method to lay the canvas on the strips.  However, not a lot of pressure is needed, as it is working with wood veneer.  Just enough to even out the fabric and push the extra glue to the edges.

This is what it should look like when you are done.  The strip in the center, with the weights stays in place, and there are two strips of canvas which will hold the tambour together.  Let it sit overnight before you try to remove it from the plywood form.  You will find that some of the glue has leaked through the strips where there are gaps.  This is not a problem, since Old Brown Glue cleans up easily with cold water.  Just work a sponge between the strips to wipe off the glue.  Do not use too much water or you risk getting the canvas wet.  Just clean the wood with a sponge and paper towels.

One detail.  These tambours generally have a first piece (with the handles) and an end piece which are thicker than the strips that make up the tambour.  You need to glue these end pieces in a separate operation, after the tambour is assembled.  Be sure to allow surplus canvas at each end to make it possible to attach these thicker pieces.

By the way, does any one want a nice American Oak Roll Top Desk?  The roll works fine...

10 comments:

mike said...

Years ago I re-did a tambour. After I glued down the canvas it shrank so I had to remove the canvas and re do it. I wash the canvas now in hot water before I apply it so it can pre-shrink

W. Patrick Edwards said...

Mike

So far I haven't had that problem. However, it's a good idea and I will do that on the next job.

Thanks for the tip.

Patrick

Ralph J Boumenot said...

Hi Patrick
Is your Old Brown Glue transparent to finish? If you had a stray spot you missed, would it show if you covered it with shellac?
ralph

W. Patrick Edwards said...

It depends on the color of the wood and the thickness of the glue residue. Normaly, Old Brown Glue is a brown color, so on darker woods, it is not that visible. On maple or other light woods, you will see the glue. The primary difference with protein glues and synthetic glues is that the oil, alcohol and solvent stains and finishes easily penetrate the glue, where synthetic glues seal the wood and prevent penetration.

Of course, since OBG is water soluble it easily cleans up with a sponge, paper towel or other damp wipe.

Patrick

nadine voelz said...

We have 2 roll-top desks. The new one(built in the last 5 years) has somehow managed to lock itself in the closed position with, of course, the key inside. The family heirloom one has a working tambor on one side only. In the last month, the top has also started to separate at the seams. How do I disassemble the desk to repair it all? Thank you.

W. Patrick Edwards said...

All roll top desks come apart. Since they are large and heavy it is essential they be taken apart to move them. Usually there are three parts. The bases with the drawers are usually two pedestals with a center drawer that can be removed, along with its front and back supports. The writing surface is the second part and is usually attached to the lower drawer units along the outside with screws or brackets under the top edge. The third part is the upper case, with the compartments inside and the roll. Normally the upper case is screwed to the writing surface with screws inserted from the bottom. The interior compartments is a single unit with small screws or nails on either side and can be removed.

The tambour roll can be removed from the upper case, only after the writing surface is unscrewed and the interior compartments are removed. Then it just slides out.

As to the locked roll, sometimes you can reach the lock from under the writing surface, but that is rare. The best way is to find another key and pick the lock. These keys are rather common and it is fairly easy to pick the lock if you know what you are doing.

Otherwise, start taking out every screw you can find and see where that goes...

Tony said...

I am currently building a roll top desk. Most of the woodworking articles I have read recommend using contact cement for installing the tambour slats. Would you recommend using Old Brown Glue for a new application, and if so, where can I obtain it? I live in Rancho Bernardo. Thanks.

W. Patrick Edwards said...

Yes, absolutely. Modified protein glues are the traditional glues used for canvas backed wood tambour construction.

You can simply drive down to my shop and pick up a bottle. Or you can order it on OldBrownGlue.com

Happy to help.

Patrick

Dan Meeker said...

Hi Patrick: You used two pieces of canvas to repair your tambour; is there a reason for two, or can I use just one larger piece? It's a standard 5' X 3' tambour.
Ty Dan

W. Patrick Edwards said...

I use two pieces so that I can have a space in the center of the strips to place another hold down board with weights. Two pieces are enough to work and I like to press the strips as flat as possible so I can push them tightly together without any lifting.