Test Bricks A, B, C, D and 8C
by Bayer for LEGO

Ingo Althofer, December 2013; newly formatted in September 2019.

Disclaimer: This brick washing experiment has not been supported or authorized by the LEGO(TM) Group and also not by the Bayer concern.

Back in the 1950's, LEGO bricks were made out of the plastic Cellulose acetate (=CA). In the early 1960's, LEGO contacted the German chemical concern Bayer with the request to develop even better plastics for the bricks. The result were LEGO bricks made from Acrylonitrile butadiene styrene (=ABS). ABS was relatively cheap and easy to process in injection molding. It allows very narrow tolerances and is much more colorfast, stable, and shockproof than CA.

In an early phase of the process, Bayer had developed four different nuances of the new plastics, with short names A, B, C, D. Bricks of type A had the smallest clutch power, B-Bricks were clamping somewhat better, C-Bricks even more, and D-Bricks had highest clutch power. C-Bricks became the standard, and in forthcoming tests for fine-tuning bricks were made where not only one nub had a "C" on it but all eight nubs of the 4x2 brick. In the scene of collectors these bricks got the name 8C.

With a handfull of such Bayer bricks I made some "dry washing experiments". In detail: I had five bricks each of the types A, B, C, D, and 8C.

These altogether 25 bricks were mixed and put in a sock which was knotted.

Then I "milled" the sock with my hands, without any use of water. I did this with exactly 200 movements, which took in total sligthly longer than two minutes. Then I opened the sock again and controlled which complexes had been built by which bricks. The next photo shows two typical results.

For each run I counted how many bricks of each type came out as single bricks and how many as parts of complexes. The total result after 12 runs was:

Type A 33 times in complexes,
Type B 29 times in complexes,
Type C 24 times in complexes,
Type 8C 22 times in complexes,
Type D 15 times in complexes.

Although this result is statistically not significant, I read a tendency: Bricks with smaller clutch power are more frequent in complexes: A before B before C before 8C brfore D.

This may sound surprising in the first moment, because larger clutch power stands for better cohesion. But larger clutch power also means that larger resistance has to be overcome before two bricks assemble.


Several people helped me before and during these experiments.

Michel Kroess from the Netherlands has collected tons of information on Bayer bricks in a web-log on test LEGO bricks. Click here!

Garry Istok from the USA gave hints on Michel's texts and photos in the 1000steine forum.

Sebastian Kirst from the German AFoL scene borrowed me some of his Bayer bricks for the "washing experiments".

Thanks to all three of them.

Bayer's Pride

The Bayer company was proud to have found the ABS plastics for LEGO, and they have all right to be. On July 10, 1967 Bayer had a full-page advertisement in the magazine "Der Spiegel":

Back to my site with the washing links