Having gone through a bunch of old 1970's Lego (I rebuild all my original sets during the Covid lockdown) I noticed that color-less transparent bricks and slopes have a lot of color variation to them.
These pieces are supposed to be "plain" glass. Not the multitude of trans-clear colors we have today. While they are all supposed to be "uncolored" I found that there are at least 4 distinct colors variants:
- Plain "uncolored" glass
- A very light grey-ish variant
- A very light blue-ish variant
- A very light brownish variant
I know that Lego has changed dyes and plastic composition over time and that has an effect on color.
However this is more than a slight variation. The faint color is noticeable even if you look at a single piece without another piece near it for reference.
Side by side the color difference really stands out.
This discoloration is not from storage conditions. This Lego has been stored in boxes in a closed cupboard (no UV exposure) at constant temperature (19-20 Celsius) for many years. Even if there was some storage effect it would have affected all the Lego in the same way.
Furthermore: I clearly remember that as a kid back in the 70's I already noticed this and I tried to use only the same color variant in a single build.
I also recall having 2 identical sets (653) with different colors for the transparent pieces and also having 2 color variants appear in a single set (420 and 445).
Was this normal back in the day or are my examples unusual?