"large PS-25 or PS-30 lamps" - Yep, would like to do that, however they need to fit into some fixtures designed for a A-21 200w lamp. Don't think a larger lamp will work.
On the other hand, the lamp would cool more efficiently with a coating if it had a bigger globe so thanks for the tip.
"should not try at home" - Will be done at in a factory like setting with oven by a exit door usually used for powdercoating.
"baked in an oven" - Had no idea this was how it is done, kind of thought it was like dipping a lamp in some paint/pigmented ceramic paste and letting it dry. Never tried it before. Any ideas on books on the subject?
"melts onto the glass" - Knew this was the right fourm to ask the question, thanks. Usually I'm the expert - at least for stage lamps.
"ventilated housings" - Why is this? Does the coating give off gas or reach a flow point temperature while close to in use temperature, or is it just to prevent overheating further the bulb?
"Other vendors" I had thought of that - Checked almost every brand, and we down grated the wattage to 100w IF blue lamps by GE for this project instead of coloring for ease in supply and getting the show out.
(They sat on their hands too long deciding like usual, and didn't comfirm they needed the lamps until the last minute.) I think this was for Kid Rock tour - I never remember what show want's what anymore after they leave the building. This week the (?)Lenny Kravitz tour (or was it Grabash) wanted to buy their 230v Euro lamps here in the US before they left. I told them, we could import them, but it would take time and be expensive. The hardest to facutate, Left Field/Right Side of the Brain Ideas, are always at the last minute! Thanks for the info, might be ready for it next time.
150w Amber Dichroic PAR38 lamps, we use in the flame pots for the Sting tour. I love dichroic filtered pars, however these fixtures are more of hurricane/bell jar with industrial cage over them type fixtures. I will look into a halogen TB-19 lamp however to see if it is available in anything over 60w. With a closer in output to the 200w lamp, but at less wattage. Probably the same temp however. Had a TB lamp for years, glass is so thick you can drop them and they don't break - great fan of them.
Thanks for the help.
Any ideas on brands and sources besides Rosco? My guess is they are not rated for much of a temperature. Also, I am thinking clear lamps over IF lamps to keep the absorption of light for temp. to a minimum, that's the right idea right? Good to know the extra heat shouldn't affect the seal of the lamp. Thanks. Will post results when and if this project comes around again - probably next time fixture goes out on tour. Thanks again.