While sorting old bricks I observed that the inscriptions printed inside show a different coding. As you can see the outside it is always a ordinary "1x2 tile with groove in good old Light Gray (item number 3069)". The inside instead appears very different.

Reading from left to right it says:

15; (c) LEGO; 032 # 
LEGO; 3 # 
(c) LEGO; 16; 35; 3069 # 
8; (c) LEGO; 032 # 
LEGO;  1 # 
3069; 36; 17; (c) LEGO # 
5; LEGO; 3; 1 # 
LEGO; 11; pat. pend. # 
LEGO;  11 # 
3069; 36; 9; (c) LEGO 

Why is that so?

You can also see that most of the bricks got on one half of the inside a yellowing. It seems that the effect is not only accruing on the surface but really eating its destruction through the material which I was not aware of.

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3 Answers 3


Has to do with copyright patents of the brick design, and warding off general infringement. Other numbers. I don't know. Design references?

Your (c) LEGO = © symbol, or the word 'Copyright' or abbreviation 'Copr.'; The year of first publication of the copyrighted work; Identification of the owner of the copyright, either by name, abbreviation, or other designation by which it is generally known.

My personal rule when buying any bricks from Bricklink.com when it comes to colors and brick type.

I use a high number of finishing bricks to cover up studs, so I try to get all tiles new.

When it comes to colors be very weary of old beat up pieces, which will ruin the look of your masterpiece. Biggest offenders for me are White, Yellow, Light Gray, and old Blue pieces that will crumble with the slightest pressure in your hand. White/Yellow always get bought new or in bulk from a LEGO store.

I tried your recent chemistry lab experiment to whiten some of these older pieces with hydrogen peroxide with mixed results. For me it's just better to buy new in bulk from a LEGO store if posible.

  • 1
    The items I am looking for are not availlable in new anymore, made in the 99ies but I got pretty good results, also with light grey bricks. I am using a 12% concentration and soak it for days, It is also available in 3% or 6%. maybe you need to take a stronger fluid?
    – fabian
    Feb 24, 2019 at 20:30

On newer pieces (maybe also the newest of the ones you show), there's a number identifying the mold and one identifying the position in the mold, allowing LEGO to trace a problem all the way back and examine the mold if a high number of errors seem to come the same mold.


While we might not know all stories behind additional numbers it has been discovered that in later years LEGO use numbers to designate the mould they are using. With massive productions moulds tend to wear out and need to be replaced. This case is well known with basic 2 x 4 brick aka. 3001, which are produced in large amounts. Latest numbers embeded on the bottom of the brick are 200+.

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