True Inside Frost Lamps

[nogden]

I was wondering why true inside frost incandescent lamps (the grayish frost, not milky white "standard" finish) are becoming harder to find from the major manufacturers.  I have always preferred inside frost lamps over other finishes in most all places where I use incandescent lamps.  The last frost lamps that I bought from GE were some 150w PS25 lamps that according to their website are now discontinued, along with many other "industrial" and vibration service lamps.

Also, does anyone know what general service lamps from what manufacturers are still being produced with a true inside frost finish?  I have noticed that the major manufacturers are not only discontinuing inside frost lamps, but they are still selling standard coat lamps under the inside frost name.

Thanks, Nelson

[briandancer]

From what I have been told by industry sales reps, this happens due to slow demand.  It is less expensive to produce, distribute, and market two major varieties than it is three. 

I have also noticed that certain bulbs have 'morphed' from a soft white to an inside frost on the label, but the bulb is more like a soft white when you look at the bulb itself.  To make matters worse, now general service incandescent lamps are viewed as an abomination by many, so sales will continue to dwindle, making it easy to justify eliminating more and more varieties and types.

Brian Dancer
Service Lighting

[nogden]

Thanks for the info, Brian.  That makes sense. I sure wish that they wouldn't call other finishes "inside frost" or any kind of frost when they are not a true frost!

[adam2]

I believe that inside frosted lamps are produced by filling the bulb with hydroflouric  acid in order to etch the inside surface (before the filament supports etc are fitted)
Use of this acid is now discouraged for safty/enviromental reasons.
The inside white coating used instead is of some harmless inert material, possibly finely powdered silica.

The traditional inside frosted finish is also regarded as old fashioned.

[nogden]

Thanks, adam2.  Glad to gather all the information that I can!

[gnildir1]

I believe that inside frosted lamps are produced by filling the bulb with hydroflouric  acid in order to etch the inside surface (before the filament supports etc are fitted)
Use of this acid is now discouraged for safty/enviromental reasons.
The inside white coating used instead is of some harmless inert material, possibly finely powdered silica.

The traditional inside frosted finish is also regarded as old fashioned.

I agree....  I was going to suggest this answer until I saw your posting...

[adam2]

I believe that from the end of this year, the sale of most types of frosted, pearl, opal, or otherwise coated lamps will be prohibited in the UK.

In theory thay will still be allowed for specialist or industrial purposes, it is only retail sale that is to be banned, however without retail sales I suspect that manufacture will cease.

Extra low voltage lamps of less than 60 volts will also be exempt, but these are little used now.