The paint is called POLANE

To determine if a phone is made of soft plastic, there are several methods to use.

If you scratch soft plastic, it will emit a foul odor, like horse poop mixed with vomit.

The plastic itself will resound will a dull thud, rather than a sharp click, when tapped with a fingernail.

The housing will have a date and shift mark, stamped inside, along the edge.

The handset caps will not have a center hole in the. The receiver cap, as an example, will have 6 holes, not seven, like the later caps.

The cords will be fat. Very early 500 sets had really fat cords that did not match the color of the housings.

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Here are some pink phones that were never painted.

[Linked Image from atcaonline.com]

Arthur P. Bloom
"30 years of faithful service...15 years on hold"