Quoted from swampfire:
I hope people understand why this topic really needs an evidence-based approach...
I do believe in the concept of an "expert witness". For example, if someone like Vid or Chris from HEP tells me that I absolutely should not put #44 bulbs under my plastics, I'm going to listen.
I am old timer EM collector who back in the day it was our common knowledge to swap out the 44's and replace them with 47's wherever the bulb was close to the backglass or to plastics. I think the guys in my circle all did this religiously and, yeah, without scientific studies. Just observation. Plenty of EM glasses had spots where bulbs had worked away the art, but I never knew for certain flaking resulting from bulbs. Uh oh, you want proof, though. I'll have to look on IPDB for backglasses that show it. You can always tell when the bulb makes a certain halo-ish effect on the glass that it's too close. On my Old Chicago backglass I removed the 44's and replaced them with 51's which aren't as bright but the bulbs are smaller. This was before repro glasses and I wanted peace of mind. I am still in the habit of placing 47's in playfield inserts, allowing 44's anywhere they are not close to anything. Superstition perhaps, but bulbs I got plenty of. 25 years later, my Old Chicago glass is still flawless. But, maybe many others are, too.
Here's some data to fiddle with, FWIW:
Lamp - Current - Watts - Avg Life in Hours
44 - 0.25 - 1.75 - 3000
47 - 0.15 - 1.05 - 3000
51 - 0.22 - 1.54 - 1000
55 - 0.41 - 2.87 - 0500
130 - 0.15 - 1.05 - 5000
259 - 0.15 - 1.05 - 5000
455 - Flasher - na - 0500
(Source: Coin-Op Cosmetics, article by Steve Young, Amusement Review, Sept/Oct 1979)
I had to put 455's in my Bally Playboy and Star Trek as I saw too many burnt pop bumper caps.
Yes, I have seen playfield plastics with lamp burns but, in lieu of proof, all I gotta say is you'd know one if you saw one. It may have been the result of using the clear colored tubes that were so prevalent, resting on the socket, encasing the bulb, and then channeled the heat right up to the plastic.
We also knew of a backglass malady called "red fade" but I guess it went away, as did polio. Plenty of examples on the IPDB.