Given that LEGO bricks are made of ABS plastic it very well could have had any number of formulations where some years it was weaker than others. Should be possible to test that.
Interesting, The Wiki says up until 1963, didn't know they changed the formula at all. Be interesting to see how well ones from before and after the change held up comparably.
I have a bunch of the very early ones, the differences with early ABS are:
- changed shape slightly, some warping
- the colours faded
- they became quite transparent
- they don't bind at all or very very loose
The early ABS ones are about as good as new other than being dirty and a couple of scratches. No discolouration, they bind just fine, no warping as far as I can measure.
Cool, they must have had some great QC with the ABS to do that well for so very very long. I'd love to see the acetate ones in a picture if they went transparent, that's a really neat "failure" mode.
