(data will be precised as more information becomes available)

The 1X2 brick was introduced in late 1952 or 1953, later than the 2X2 and 2X4 bricks because the initial system was based on a double (2X) modulus.

The first type (1X2vs01) is illustrated below. It had no logo on the studs and "LEGO" was inscribed in block letters under the brick. The molds were not numbered. Bricks had one or two (symetrical) lateral slots.

There were two different "LEGO" logos, of which one (seen below) was thiner and wider than the other. The molding pip was on the front, as shown below, at left. The studs are very slightly concave.

This version was only seen in white.

This next version to be issued was seen in four more colors, besides white and must have been the brick that normally integrated the 700/ construction boxes.

It has no logo anywhere on the bricks but inside bears the mold number ("1" and "2" were seen).

The studs are slightly concave and the top is rounded when seen from the side (left). Seen from above, the sides of the studs seem taller than the top- see the white brick in the picture below. This morphology proves that they are contemporary with the 2X2, 2X3 and 2X4 bricks that bear the dog-bone "LEGO" logo inside.

Molding pip on the side (see the blue and white bricks left). Slotted but occurs (rarely) unslotted.

Circa 1955 a new mold was produced. Bricks now had the logo on the studs and a mold code inscribed beneath (see figure below). The code was made of a numeral and eventually one or two dots differently positioned around the numeral. Numbers from "1" to "8" were seen.

The studs are not hollowed and as a consequence of not enough injection pressure being used, or of the mold opening too soon, the plastic collapses inwards resulting in very concave surfaces. Since this feature was not seen before, either a new material was now being used or, more likely, new machinery with a faster molding cycle.

Molding pip on the front.

NOTE: The fact that only white and red bricks were seen with only one slot, produced when the slotted system was being abandoned, suggests that these bricks were used exclusively on Set 1236 (Garage with door) and sold for use with set 1235 (Automatic garage door) as the older door frame needed slotted bricks as retainers.

The problem with the concavity of the stud surfaces called for new molds. The fourth version of the 1X2 brick was introduced circa 1956/57 (see figure below). Studs are now hollow (with a 3mm diameter hole) and the brick is no longer slotted.

As in version 03 the LEGO logo is lengthways on the studs. Mold numbers used are "1" to "28" and there are also unumbered bricks. The same number may correspond to different molds (maybe because worn molds were replaced with new ones similarly numbered). Molding pip on the side corner.

Bricks of this type were certainly used in 1957-59 but were replaced with a new version early in the 1960s. Seen in white, red, transparent and blue, all manufactured with the same molds. Probably used in the early yellow bricks as well.

The fifth version of the 1X2 brick is almost identical to version 04 but the LEGO logo on the studs is now sideways. Mold numbers seen are "1" to "47" and there are also unumbered bricks. Molding pip on the corner.

Bricks of this type were certainly introduced after the new "Pat Pend" 2X2, 2X3 and 2X4 bricks with tubes had been in widespread use for several years.

The fifth version of the 1X2 brick above is the last that will interest us. However, the following figure illustrates a newer version, introduced in the mid 1960s. It is characterized by a tube underside (full or hollow) that inserts between the studs of the brick below.

The "LEGO" logo on the studs is engraved sideways but the lettering type is taller and somewhat thinner.