Tuesday, December 31, 2013

Respect The Screw

Absolute Proof of Authenticity
I refinish and restore antique furniture.  I have taken apart and repaired or refinished over 10,000 pieces of antique furniture in my 45 years.  I am fortunate to see the "guts" of some amazing pieces.  I get to see the tool marks and construction details up close.  I get to examine the nails, screws, hinges, pulls and all sorts of other interesting hardware that exists on these pieces.

Over the years I have developed a deep respect for original hardware which is still in its place and has never been removed.  I think it is certainly one of the most important clues as to the actual age of the piece.  Fakers are usually more concerned with the wood elements and hiding the new wood or cut wood edges with fake patina and stains.  Until recently, they have not been so concerned with using period and appropriate hardware.

In fact, it is possible to recycle old hardware onto newer reproductions, but more difficult to find enough old hardware from the same period that matches.

When I look at antique tables, the very first thing I look at are the hinges and screws.  Iron hinges went through a very clear evolution during the late 18th and first half of the 19th century, as did the screws that held them in place. Until the industrial revolution fully took over this job, all furniture hinges were made by blacksmiths.

The earliest iron hinges were straps of iron bent around a pin and forged together.  These hinges clearly show the smith's work and have a distinctive taper to their thickness.  It is pretty hard to break one of these hinges, since you would have to break the pin or tear the iron.  Not going to happen.

Soon they added rivets in iron to hold the straps together.  On all these hinges the bevel for the screw head is hand cut and irregular.  In fact all the holes are where they end up.  Nothing is even or symmetrical.  Just not important, since they were not seen in the finished product.

Note Scribe Lines For Axis Alignment
Note Saw Cuts For Creating Mortise
Eventually, around 1850, a tool was developed that could form the iron or brass into a circle to hold the pin.  There was no longer a need to make hinges.  These "butt" hinges, as they were called, were cheaper and all made the same, which made installation faster.  However, if you pulled strong enough on the door or leaf, the metal would just unwrap and pull open.  Not too strong, but it works under normal conditions, so it prevails.

The screws went through a similar evolution, from completely hand filed to cast to the invention of the modern pointed gimlet screw in 1846.  There is a wonderful research pdf from the Boston Museum of Fine Arts, by Christopher White online which illustrates the different periods of screws.

A Thing of Beauty
You can see it here:  Wood Screws in North America
Nothing Touched Since 1820

It is important to recognize that modern screw drivers should not be used on period screws.  Period screws were fastened with two tools, a gimlet and a turnscrew.  The gimlet was used to create the pilot hole, since the early screws were blunt and not tapered.  The turnscrew is the original name for the screwdriver, but the tip was not square.  The tip was tapered, like a "V."  The reason the tip was tapered was because the slot in the head of the screw was not flat bottomed.  Being cut by hand with a blade left the slot slightly tapered.  Therefore, using a modern screwdriver, which has not been modified, will cause the tool to slip out of the slot, damaging the oxidation on the head of the screw.  This is how you can recognize original screws which have never been removed compared to original screws which have been removed and reinstalled using the wrong tool.

The photos of all 6 hinges on this post were taken from the same table.  It was made in Baltimore around 1820 and is in two sections, each with drop leaves.  Each leaf has three hinges, all completely untouched by modern woodworkers.  Although the table was refinished some years ago, the refinisher had the good sense to not remove the hinges.  I would like to thank him for his knowledge and consideration.

Bottom line: when you find original evidence of age, leave it alone.  The future collectors will thank you.

This One Had A Loose Screw


Chuck said...


Once again I would like to thank you for another lesson in antique construction and materials. I presume the scribe lines that locate the pivot point extend the length of the table. Also, is the short leaf of the hinges mounted on the frame or the leaf. I'm guessing the frame but I'm a novice.

The collection of hinge photos is quite educational and clear evidence of handwork.

W. Patrick Edwards said...

You are correct that the short end of the hinge is on the top and the longer end is for the leaf, which is offset due to the thumb rule joint.

I believe, also, that the scribe line for the pivot axis of the hinge is also helpful for making the thumb rule joint. Since the scribe line itself is lined up with the top edge of the table, I would think that the worker started by scribing both top and bottom the same depth. Then, using the thumb rule plane, he would plane down to the scribe line on the top edge. That would allow him to work evenly, watching both lines as he worked.

When he reached the top edge, the male portion of the joint was done. By scribing the bottom edge of the leaf, he could likewise plane the female shape of the joint and both would fit nicely.

I should have mentioned that this evidence of work, like scribe lines, is just as important as original hardware. They all tell a story, if you are able to read it.

JC said...

This was a fascinating read. I actually have a drop leaf table, which is/was in extremely poor condition that I've been restoring on and off for a few years. It's a simple farmhouse table in solid birch, and it really didn't look that old, but it has these same hand forged hinges, with the same sort of irregular screw placements.

Sadly, I had to remove the screws and hinges in order to strip and repair everything. It was a lovely mint green. I still have all the original hinges and screws in a bag.

W. Patrick Edwards said...

Often it is necessary to remove hand made screws. In that case, we take a piece of cardboard or styrofoam and place each screw in its exact location on this pattern. We can make notes if necessary.

Therefore, when it goes back together, all the screws are easily placed back in their original position.

Since the screws are different lengths and thread pitches, it is important to keep them in order.

If the holes are completely stripped out, then a bit of glue and wood will repair the damage. Wait for the glue to set, run a gimlet (or new screw of appropriate size) into the filled hole to create the threads and remove it. Then you can replace the hand made screw properly.

Don't forget to modify your screwdriver to fit the slot.