Why LEGO uses Flexible Rubber in some hairs?

[Vitruvius]

I would like to know if there is a reason for some hairs being made of flexible rubber instead of hard ABS plastic like majority of them. For example Cho Chang figure in the Harry Potter line. Why that hair has to be made of that?

[Lyichir]

5 hours ago, Vitruvius said:

I would like to know if there is a reason for some hairs being made of flexible rubber instead of hard ABS plastic like majority of them. For example Cho Chang figure in the Harry Potter line. Why that hair has to be made of that?

Sometimes it's a molding consideration (like with the old Exo-Force hair), where rubber-like plastic allows for sharper points or thinner details than molded ABS. Lego Friends has used mostly rubber hair pieces since the beginning, due in part to the often more elaborate hairstyles.

The hair you mention for Cho Chang is an interesting case since while it was originally molded in a more flexible, rubber-like plastic, some more recent sets (like the Monkie Kid City of Lanterns) have featured that same hairpiece in solid plastic.

[jimmynick]

On 11/24/2022 at 1:57 AM, Lyichir said:

sharper points or thinner details than molded ABS

This is an interesting thought — I'd always assumed it was because hairpieces with sharp edges or fine details ran the risk of breaking if made from ABS (for instance the Dr. Inferno hairpiece https://www.bricklink.com/catalogItemInv.asp?M=agt013). Can you speak at all to the practicality of modeling hairpieces with rubber rather than ABS? It seems to me that ABS is just fine for fine detail as far as casting etc. goes.

[Lyichir]

1 hour ago, jimmynick said:

This is an interesting thought — I'd always assumed it was because hairpieces with sharp edges or fine details ran the risk of breaking if made from ABS (for instance the Dr. Inferno hairpiece https://www.bricklink.com/catalogItemInv.asp?M=agt013). Can you speak at all to the practicality of modeling hairpieces with rubber rather than ABS? It seems to me that ABS is just fine for fine detail as far as casting etc. goes.

Yeah, I should clarify—the risk of breakage is as important as any limitation on what CAN be physically molded in ABS. Thinner details that could break or bend out of shape in ABS can make a more rubbery plastic, which resists damage of that sort, a more practical option for certain hair pieces.

[Johnny1360]

Very interesting, I would have never considered that reason, I always thought it was more of a safety concern. As in not being able to easily puncture little Johnny's epidermis.