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The Keys to Antique Furniture Locks

by Fred Taylor (02/20/09).

Most of us who are interested in antique furniture have, at one time or another, run across what seemed liked an intractable problem at the time: the locks on an antique chest or desk. The usual approach is to either ignore the locks or take the attitude that if the key is around, great, if not, no big deal. But locks don’t have to be such an enigma. In fact, most 18th-, 19th- and early 20th-century American and some European locks are quite simple and easy to repair and key.

Cabinet and chest locks come in three major designs: full mortise, half mortise and surface mount. Mortise refers to the cut out portion of wood in which the lock is mounted. A full mortise lock is fully enclosed by the drawer front or door in which it is mounted. Only the selvage—or top edge—of the lock is visible on the lip of the drawer or door, and nothing shows on either side. Full mortise locks are usually found on higher-quality 20th-century pieces, although they are used in rare cases in 19th-century goods.

A full mortise lock is completely enclosed in the wood with only the selvage visible.

A full mortise lock is completely enclosed in the wood with only the selvage visible.

A half mortise lock is exactly as it sounds—half exposed. The top selvage is visible, but so is the back or lock plate of the lock on the inside of the drawer front. Also, usually visible on a half mortise lock are the screws or nails that hold the lock in place. The half mortise lock is almost universal on 19th-century American and English case goods.

A half mortise lock is implanted part way in the wood but leaves the back plate visible form the inside.

A half mortise lock is implanted part way in the wood but leaves the back plate visible form the inside.

The simplest design is the surface-mounted lock that is not inset in the wood at all, but is mounted with screws or nails flush to the inside surface of the drawer or door. These locks are most common on early 20th-century pieces and on inexpensive reproductions, and are commonly used as replacement locks by inexperienced restoration “experts.”

A surface mount lock is simply nailed or screwed to the interior surface.

A surface mount lock is simply nailed or screwed to the interior surface.

The purpose of a lock, of course, is to keep someone out of a private place. But since most locks are designed only to keep honest people honest, a determined trespasser can almost always find a way in. Most older and antique furniture locks work on the simple idea of a key moving a bolt through the lock and into the adjoining frame member. The key usually fits over a center pin of a given size and rotates around it. The blade of the key engages a semi-circular cavity in the bolt and moves it forward or back as the case may be. The bolt, however, may have a built-in resistance to impede the use of an unauthorized key. The resistance is a notch in the bolt that engages a surface of the lock housing and prohibits the bolt from moving. A spring holds the bolt notch fast to the face of the lock housing. The key must not only be the right size to move the bolt forward and back, it must be the right size to compress the spring and release the bolt so it can move. Most bolts have two notches, one in the locked position and one in the unlocked position.

This diagram show the parts of a half mortise lock.

This diagram show the parts of a half mortise lock.

In addition to correct barrel size and blade size, a lock may employ other features to prevent the entry or use of a bogus key. The most common is an inside ring of raised metal, concentric to the pin that requires a notch in the key.

These keys are all “notch” keys with cuts in the face of the blade.

These keys are all “notch” keys with cuts in the face of the blade.

This illustration shows how a notch key works over the internal security ring of a lock plate.

This illustration shows how a notch key works over the internal security ring of a lock plate.

This feature is easy to overcome by inserting a new blank key in the lock and working it back and forth. This will put a mark on the blank where the notch should be and it can be cut out with a hack saw. A little practice makes nice notches. A variation is two inside rings of different heights that require two notches of different depths but that’s a detail. A more serious impediment to the interloper is the accursed English “lever” lock. This lock relies on a series of spring loaded levers, each of different thickness to deny entry. The levers must be aligned in a perfect line to allow the bolt to pass but since their thickness is random and hidden, figuring out a cut pattern is very difficult. This lock requires notches to be made on the bottom of the key blade rather than on the face of the blade and is much more difficult to fabricate. Most lever locks are labeled as such. Apparently, the 19th-century English had more of a need for security than we did. This is one case where if you don’t have the key, don’t worry about it.

The key to a lever lock requires notches to be made on the bottom of the key blade rather than on the face of the blade and is much more difficult to fabricate.

The key to a lever lock requires notches to be made on the bottom of the key blade rather than on the face of the blade and is much more difficult to fabricate.

The second most-common problem in the old locks, besides no key, is a broken spring. Symptoms of broken springs include bolts that can be moved without keys, bolts that don’t lock into position or bolts that do not line up with the holes in the selvage. Removing the housing around the pin and bolt will reveal the condition of the spring. Most springs are merely flat pieces of tension steel inserted in a slot in the bolt and wedged against the housing. If the spring is broken, remove it from the slot by punching it out with a small screw driver. Then replace it with the spring from a salvaged lock, or better yet, with a piece of a modern bobby pin. It works very well.

The most common problem with old locks is neglect, especially if the piece has been worked on before and the locks were not removed before stripping and finishing. In this case the locks should be removed, cleaned thoroughly and submitted to liberal applications of WD-40 before any key is tried at all.

Blank keys are available from lots of places including, Van Dyke Restorers in Woonsocket, SD., or your local locksmith and flea markets. Collect as many steel keys as you can to try stubborn locks with before you cut soft brass ones. Brass keys may break in a reluctant bolt. Good luck.

Fred Taylor is a Worthologist who specializes in American furniture from the Late Classicism period (1830-1850).

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24 Responses to “The Keys to Antique Furniture Locks”

  1. Sadie says:

    Mr. Taylor, I can’t wait to see your new articles each time they are posted. Your articles are the reason I continue to go to the WorthPoint site each week. Thank you for sharing so much good information with your followers. With your guidance (I just ordered your book, DVD and CD from your furnituredetective.com website)I should be a furniture expert in no time – at least that is what I am hoping for.
    Thanks again, Sadie

  2. Mary Jane says:

    Mr. Taylor, I just finished reading your nails article and just discovered that you wrote an article on locks and keys as well. You continue to deliver some great information in such an easy to understand format. I can’t wait to share this one with the other dealers in the mall where my shop is. Is there a way to search the WorthPoint site to see what else you have written? I am thinking of starting a file with all of your articles so that I can use them as future reference. Do you have any books for sale or is there anywhere else I can read what you write? If you offer classes or do speaking engagements, can you tell me where I may go to attend one of your events?

  3. Jane Simpson says:

    Fred, I have been reading your work in Antique Week for many years and am so excited to see more of your articles on this site. You always provide a wealth of information to your readers. I just want to say “thank you”.

  4. James Cook says:

    Mr. Taylor, thank you for this very helpful and informative article about locks. I learned a lot of new information.
    James Cook

  5. Ken Hampel says:

    Mr Taylor,
    Thank you for this wonderful article! My wife and I have an old china cabinet with a full mortise lock. It has worked fine for a few years, but now the key will not open the lock. The key is notched. As the key is turned, it seems to get stuck before it engages the bolt. Based on you terrific diagrams, I would guess that the security ring may have been bent slightly and that this denies the key the ability to turn fully. Is this a reasonable guess in your opinion? Do you have any suggestions as to how we may overcome this problem? Thanks again for the article.
    Ken

  6. AbbeyTek says:

    Great job this is a really good blog for this topic.
    I sell antique keys of all kinds and find little to no info out there on the net to help people learn about locks and keys . Thanks for taking the time to share your info.

  7. David Golman says:

    On a whim and for a new distraction/hobby I bought what really looks like an old, neglected but interesting peice of furnature from the thrift store. It has two full mortise and three half mortise locks, no keys. I would like to take the locks out of their mounting (to clean, assess). After removeing all the obvious screws, I could not prod, push, hard tap… either type of lock out. I did not want to force or damage the edges so did not push harder. There is no obvious adherents from old coverage.

    How do you safely remove old half or full mortise lock from their mounting?

  8. Amanda Byelich says:

    I have an antique record holder that my grandmother gave to me. For a year I stored things in it and used the lock with no problem. Recently my fiance lost the key, and the door is locked shut. I believe it is a half mortise. I tried keys from a china cabinet and an old cedar chest, and both are too thick. Is there an easy way to pick the lock?

  9. Robert Harrison says:

    Mr. Taylor,
    Your article offered a lot of information. I have experience creating keys as a professional locksmith and I’d like to share something that worked well for me.
    I use the soot of a small burning candle to carbon black the blank. The blackened blade is inserted into the lock and wiggled with the back and forth motion you mentioned. When withdrawn the blank is now precisely marked where it encounters the security ring. Cuts are then easily managed.
    Due to a near fatal accident I no longer work as a conventional locksmith. As owner/operator of Key Creator in the San Francisco bay area I enjoy hand fabricating blanks and finished keys for two piece mortise locks. More than thirty years as a metal fabricator developed my passion for fabricating keys for crypts and other large two piece cased mortise locks when blanks and/or keys are impossible to get.
    Bob Harrison

    • Priscilla Yocom says:

      I live in Walnut Creek (East Bay area). I have a key to an antique cedar chest which I would like to have duplicated. Are you still creating keys as mentioned in this article? If so, I would like to arrange having you duplicate this key. Hope to hear from you.
      Thank You,
      Priscilla Yocom

  10. Leah says:

    this was exactly the info i needed! thank you so much for doing what you do :-)

  11. Ian says:

    The pin in a half mortise chest lock has fallen out of the shaft/mount in the back of the lock. As a result, the key to the chest will no longer throw the bolt to unlock the chest lid. How can I reinstall the pin?

    • Fred Taylor says:

      The center pin was originally installed by a machine in a “press” fitting. It is very hard to duplicate that fitting by hand. But there is a sure way to fix the problem that I have done dozens of times.

      First remove the lock from the door or drawer. Then find a small sheet metal screw that will screw tightly and securely into the hole and make sure the key can fit over it. Use a sheet metal screw rather tha awood screw becasue the sheet metakl screw is cylindrical. A wood screw is tapered. If the key doesn’t fit right file down the threads. Using a grinder or file remove the pint of the screw. Screw the screw in place in the back plate. Then for appearances sake grind or file the back of the screw until it is flat and removes all traces of the slot. Then apply a spot of two part epoxy glue around the back of the screw to secure it to the back plate.

      That should do. Just make sure it works before reinstallation. Don’t forget to WD 40 the mechanism.

      Good luck.

      Fred Taylor
      http://www.furnituredetective.com

  12. Cheryl Townsley says:

    Mr. Taylor, your site is very helpful, but I have a surface-mounted lock with a key stuck. I’ve taken the lock off and WD40 all over the place, key will not turn, can’t get the little plate to move either direction. The other lock is just stuck in the locked position. Any suggestions? Thanks for your help, Cheryl

  13. Fred Taylor Fred Taylor says:

    Cheryl – At this point it is hard to say what the problem may be. If you want to go to the trouble, email me at info@furnituredetective and I will email you back with my mailing address. You can send the locks to me and I will take a look.

    Fred Taylor

  14. Owen Smith says:

    I restore antique trunks. I have one from around the civil war period. It is a half mortise type lock brass. The lock mechanism works fine but it locks automatically when the lid is closed. Where can I get a key for this lock. Without a key the trunk has not much antique value.
    Thanks for any help you can provide

  15. Replacing locks on antique furniture can be a hassle and almost impossible at times. These locks are almost impossible to fix because they are so old. But if I can get you back into your vehicle. Please don’t hesitate to call me @ 407-506-0460 for all of your locksmith related needs.

  16. Brian Jones says:

    Hello this is Brian From Rhinoceros Security in San Francisco. Many people from around the world have come to my shop for antique furniture and skeleton keys. I’m sorry to say that I’m closing my shop and going to mobile only. However if you still need antique furniture keys I can still provide them for you if you e-mail me at brian@rinosecurity.com or you can call me at 415-751-2087. Thanks.

  17. Karen says:

    Hi, I have half mortise locks on an old dresser. In a burglary, they actual stole one of the drawers leaving the dresser useless. So, I’m selling all the hardware on eBay, but I don’t know how to remove the locks. There are NO screws on the backside of the lock, only a small hole. How do I safely remove the locks for shipment?

    Thanks!!!

    • Fred Taylor says:

      Karen – The half mortise locks with no screws are from the turn of the century and are simply pressed downward from the top of the drawer into place. You can remove them by using a hammer and a blunt chisel or screwdriver, driving the lock up and out of the drawer through top ledge. You may break off some wood but I gather that at this pint it doesn’t matter.

      Good lcuk.

      Fred Taylor

  18. Suzan says:

    Hi MR Taylor
    I’ve read your website and didn’t see my particular problem. I have an old (probably late 19th century) oak buffet with curved glass and locks. All the doors have locks and they are now locked. The problem is the key is stuck in one of the doors, it will not move at all. When I went to lock it, the key turned then stuck. I’ve tried spraying WD-40 in the key hole (where I could) and wiggled the key, pushed the key back and forth but to no avail.
    I’ll call a locksmith, but I thought I would see if you might have a solution or tell me what to ask the locksmith. I figure I am going to need someone who knows old locks. I live in San Diego.
    Thank you for your reply.
    S

  19. Jessica Zahn says:

    We recently purchased from auction a full silver flatware
    service. The description of the item states:

    “English Silver Flatware Service Garrard & Co., third quarter of the 20th
    century, all fitted in a George II style mahogany serving table.”

    The table contains 2 drawers, and each have a lock. The item did not come
    with keys so I took it to a locksmith, where I was told one of the locks is
    faulty, and does not work.

    Locks are stamped ‘AF&S Secure Lever’.

    Please advise if this is a type of lock you could replace/repair, or if you advise to leave well enough alone as it would ruin the table.

    Thank you,
    Jessica Zahn

  20. JL Wood says:

    paxton@ix.netcom.com

    Message flagged

    Tuesday, July 10, 2012 5:42 PM

    Mr. Taylor,
    I have a oak half n half, with large bowed glass door on the left, and small leaded glass door over the fold out desk on the right.

    My problem is in the lock on the small door is broke. I am looking for a smaller version of the full mortise locks that are not too hard to find, 1 1/2″ in length.

    The specs I need are:

    Depth: 5/16″

    Finish: Polished Steel

    Length: 1″ (This is the difference from the ones I have found. They are 1 1/2″ in length)

    Material: Steel

    Width: 1″

    Location of key pin: 7/16″ from edge

    Any help would be greatly appreciated.

    JL Wood

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