Reupholstery 101 Part III

On March 22^nd, we talked about the twisting action of the nails grinding against the wood as it moves in and out of the frame. I will document the damage after the jute webbing is removed. Today another problem is discussed; tightening the stretched out webbing in lieu of replacing it.

Notice the light colored strip of fabric that is visible on top of the webbing running diagonally to the metal strap we discussed last week.  This was the first attempt to shore up the webbing via a quick fix. 

Photo: SHS

Over time all webbing stretches out. This fix takes the slack in the length of webbing and literally nails it to the frame.

Keeping in mind that the chair is upside down, the process is as follows. First the strip of strong fabric, in this case vinyl was placed on top of the webbing. Then the technician placed pressure on it and forced it down.  With even more pressure it was forced sideways against the inside of the chair rail; at which point tacks were driven through the strip and the webbing at an angle into the chair seat rail.  

 The slack in the length of webbing is nailed to the frame, making the webbing tighter and forcing the springs back up to their original height.

Photo: SHS

This process is detrimental to the chair for two reasons. The chair frame is receiving more nails than it was engineered for. Plus It was manufactured with the idea that only upholstery tacks would enter the frame from the top and the bottom of the rail.

The fabric method puts nails at an angle through the rail. In the prototype process, the grain of the wood is taken into consideration as the cabinetmaker considers how the chair is joined and weight will be distributed. Nails entering the seat rail at an angle were not taken into consideration and will at first cause bits to fracture off and eventually larger portions of the wood to split.

The metal strap method mentioned on March 22nd also causes damage to the wood frame.

Photo: SHS

The twist nails(1") used to attach the strap to the frame are longer than upholstery tacks (3/4") and consequently forced deeper into the wood. Upholstery tacks are tapered. They separate the fibers as they enter the wood. But the twist nail shafts are thicker than upholstery tacks and the shaft is twisted: as it enters the wood it crushes the fibers. 

These ill considered repairs were not anticipated by the woodworker.* 

Pictured below (left to right) are a twist nail, a size 14 upholstery tack and a size 8 upholstery tack.  Note how the shafts of the upholstery tacks are tapered and that of the twist nail is only tapered at the very tip.

Photo: SHS

You might be wondering why two attempts were made to shore up the webbing?!?  

Replacing the webbing on the bottom of a chair hinges to another time consuming job; that of removing, reinstalling and retying the springs.  It is a time intensive process which requires a certain level of skill.

Illustration by the Author

Only the craftiest upholsterer can retie the springs to new webbing through the webbed bottom. 

Photo: SHS

So to save time and/or avoid work many upholsterers technicians ignore the obvious and strap on whatever quick fix they can thereby compromising the frame of the chair.

The integrity of the blog chair frame has been weakened.

As the nail continues to turn....

Theresa

Yummy Furniture and Design

theresamhs@sbcglobal.net

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*For more on the wood's qualities and how people crafted in the medium, see John T. Kirk's, American Furniture, Understanding Styles, Construction and Quality, New York, Harry N. Abrams. Section 2, pp 17-25.

ReUpholstery 101 Part II

As mentioned earlier today I am posting some photos of the rip-down process.

The rip-down is the first step of the re-upholstery process; during which the spent materials such as webbing, fabric, tacks, twine, etc. are removed. This enables us to get a good look at the frame and see if it needs repair.  I always flip my pieces upside down and take a look at the bottom.

Photo: SHS

Then I place the chair upside down on a set of padded work horses. 

The first items to be removed here are the metal webbing strips because they were installed over the jute webbing in lieu of replacing it when it became weak and sagged. This method of shoring up the jute webbing should be avoided at all costs. It employs a twist nail driven through the holes in the strap and into the frame.  They do a great job of holding the strap in place at a dear cost to the chair: when they are both installed and removed the twisting motion weakens the chair's frame.  

 Notice the twist of the metal on the of the nail protruding from the metal strap webbing I've removed.

Photo: SHS

Look at the head of the nail in the metal strap and notice the faint black line I drew across it. The line is vertical in this shot.

Photo: SHS

Now look at the same nail and again and notice the faint black line is at a different angle.  This corkscrew effect occurred as I pried the nail from the frame by means of a tack puller. If this were a standard tack or nail the line would have stayed in the same vertical direction it was in the previous photo

.

Photo: SHS

The twisting action grinds against the wood of the frame as it moves. We will be able to see the damage once the jute webbing is removed.


As the nail turns....

Theresa

Yummy Furniture and Design

theresamhs@sbcglobal.net

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Link up at LinkedIn