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LEGO switched from cellulose acetate (CA) plastic to ABS plastic in 1963. They continued to distribute CA pieces in sets until their existing supply was exhausted, so during the transition beginning in 1963 both types of pieces were sold in sets. In North America, LEGO pieces were manufactured beginning in 1961 under license by Samsonite, which continued to ...


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As 62Bricks has said, this can be an art. Based on my experience (in the UK): CA bricks tend to have less clutch (stickiness to other bricks) than ABS bricks. I'm not sure if this is because they are more prone to wear, because they tend to warp or just because they're old and worn out. Nevertheless, some of my CA bricks are so non-grippy that they're all ...


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The yellowing that is common in some colors is caused when a fire retardant that was added to the ABS plastic breaks down under UV light. One of the elements used in the fire retardant is bromine. When the chemical degrades, bromine atoms can be freed and can make their way to the surface of the brick where they bond with an oxygen molecule (O2) and take ...


2

To sort ABS bricks from CA bricks can sometimes be difficult. What helps is they SOUND differently. An ABS brick emits a higher pitched sound when dropped than a CA brick which sounds more like a "thud". So if you are not sure, drop the brick and the sound will tell you what it is.


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