This was invented by Carl Wolf and sold through his company Merriss Magic. It is an an improvement to Carl’s earlier effect Lock of Gilbraltar c. 1958. It became the standard by which many later similar locks were measured.
The grandfather of modern mentalism locks was this ground-breaking offering, created by Carl Wolf. Wolf presented stage shows under the name Merriss. He attended local magic club meetings in Louisiana in the 1960s and came out with his commercial product in 1960. He called it Key-R-Rect and sold the lock through his company, Merriss Magic. The company name is often mistakenly cited as “Merrill,” possibly in confusion with the long-standing and widespread popularity of R. D. Merrill’s color-changing knives.
The buyer of Wolfs Key-R-Rect got what appeared to be a regulation Master Padlock and 11 keys. The audience was only aware of six keys. Five keys were tried and did not open the lock. The sixth key did open it. All six keys were sealed in small pay envelopes and mixed by a spectator. The mentalist chose one envelope without looking. The key in that envelope was tried in the lock and-voila!-the lock sprang open.
This plot sounds very similar to Annemann’s Seven Keys to Baldpate routine, and in fact was based on it. However, there was a big difference. With this version, only six keys were used and they could all be kept in sight during the entire routine. There were no extra keys, and there was no need to drop them in a suspicious bag, so the handling was much more open and above board.
What made the routine work so fairly was a sneakily gimmicked lock. Wolf bought commercial grade Master padlocks, disassembled them, altered the interior mechanism, and put them back together. Five of the keys were identical. One had a special cut to the bits. Before that key was put into the lock, none of the other five keys would open it. When that special key was turned in the lock, it configured the interior mechanism of the lock to a state whereby any of the other keys would open it.
Any or all of the other five keys could be tried as often as desired, before the special key was used, and none would open the lock. But after the special key opened the lock and it was closed again, any key worked.
The original product came in a plastic snap-close box lined with foam. It included the lock, five working keys, one special set key, and five additional keys, none of which would ever open the lock. These could be switched in if the performer felt the audience might want to examine the keys and lock after the performance.
Key-R-Rect was a masterpiece of clever engineering and it was widely recognized as such. Besides, it was so ingenious a method, that magicians were buying it just to admire the workings.
While many things in magic are ripped off by unscrupulous dealers or manufacturers and many props are copied and sold without regard to the originator, Key-R-Rect was not. The reason is that re-engineering the lock was a very difficult feat to accomplish. Warded Master Locks are made to be secure, assembled by a series of layered plates of steel mounted sideways and riveted together.
Getting to the interior means destroying the rivets without marring the outside edges of the plates. Re-assembling the lock means re-riveting the plates together with factory-like rivets, again without marring the surface. Wolf had figured out how to do the necessary work, but few machinists of the day could equal his talent and efforts.
Key-R-Rect props have mostly held up over time, Even now, 50 years after their construction, many magicians have a model that still works. The altered mechanism was not infallible, however, and performers who frequently used their lock sometimes found that it would wear out internally and become unreliable. Still, it set the bar for lock tricks and gimmicked locks fairly high, even back in 1960.
Effect: You remove five keys from your key case. One is handed to each of five spectators. A colored ribbon is tied to one key as a marker. You display a box. It may be nothing more elaborate than one that formerly contained candy. It is of the type where the sides of the lid are as deep as the sides of the box. There are holes through the sides of the box and lid. One leg of the bow of a padlock goes through these holes. It is locked. The spectators try their keys. Only the ribbon marked key will open the lock. After each failure, the first four spectators drop their keys in the box through a slot in the top. When the fifth spectator succeeds, the lock is removed and snapped shut through a button-hole of his coat. The lid is discarded.
The box itself is used like a tray. The fifth key is added to the other four, after the identifying ribbon has been removed. The keys are mixed and each spectator removes one and holds it concealed in his hand. Selections are made while your back is turned. A fter holding the lock for a moment to the back of each spectator’s hand, you announce who is concealing the key that will open the lock.
A test proves that you are correct.