Metal Halide color

[John120/240]

Church sanctuary location. 18 metal halide fixtures mounted on coloumns for up lighting. Replaced several lamps over the past

six months & the new lamps have a different color. Original lamp color was a blueish white which was pleasing. The replacement

color is greenish yellow which looks like ........... Does the life of the ballast affect the lamp color ? Will purchase 18 lamps at the

same time hopefully they will be all the same color. What are your thoughts ?

 

[qcroanoke]

Church sanctuary location. 18 metal halide fixtures mounted on coloumns for up lighting. Replaced several lamps over the past

six months & the new lamps have a different color. Original lamp color was a blueish white which was pleasing. The replacement

color is greenish yellow which looks like ........... Does the life of the ballast affect the lamp color ? Will purchase 18 lamps at the

same time hopefully they will be all the same color. What are your thoughts ?

From Wekipedia so take it how ever you want:
Color temperature





Output spectrum of a typical metal-halide lamp.
Because of the whiter and more natural light generated, metal-halide lamps were initially preferred to the bluish mercury vapor lamps. With the introduction of specialized metal-halide mixtures, metal-halide lamps are now available with a correlated color temperature from 3,000 K to over 20,000 K. Color temperature can vary slightly from lamp to lamp, and this effect is noticeable in places where many lamps are used. Because the lamp's color characteristics tend to change during lamp's life, color is measured after the bulb has been burned for 100 hours (seasoned) according to ANSI standards. Newer metal-halide technology, referred to as "pulse start," has improved color rendering and a more controlled kelvin variance (?100 to 200 kelvins).

The color temperature of a metal-halide lamp can also be affected by the electrical characteristics of the electrical system powering the bulb and manufacturing variances in the bulb itself. If a metal-halide bulb is underpowered, because of the lower operating temperature, its light output will be bluish because of the evaporation of mercury alone. This phenomenon can be seen during warmup, when the arc tube has not yet reached full operating temperature and the halides have not fully vaporized. The inverse is true for an overpowered bulb, but this condition can be hazardous, leading possibly to arc-tube explosion because of overheating and overpressure.

 

[hurk27]

When I need lamps to be a uni-form color I order my lamps from Venture Lighting, the owner of the company Wayne Hellman developed metal halide for GE and there quality and customer service is great, give them a try and tell them what color your looking for and they can fix you up in most cases, other things that will or can cause problems with color is voltage drop, and different brands of ballast that supply a slightly different voltage to the lamp. but venture can walk you through most any problem:

Venture lighting

 

[John120/240]

Thank You, hurk27

 

[Hv&Lv]

I know the ones that have no coating look "green". I like to put the ones with the white coating in our lamps.

 

[LEO2854]

Church sanctuary location. 18 metal halide fixtures mounted on coloumns for up lighting. Replaced several lamps over the past

six months & the new lamps have a different color. Original lamp color was a blueish white which was pleasing. The replacement

color is greenish yellow which looks like ........... Does the life of the ballast affect the lamp color ? Will purchase 18 lamps at the

same time hopefully they will be all the same color. What are your thoughts ?

In a situation like that where color is important it is good practice to change them all at once otherwise the difference in color will be noticeable not only that brightness will come into play.

As a metal halide lamp ages by run time the light output decreases over time, also the color changes over time as well ,

If you have 18 together all installed at the same time they will all look very close to the same through out the life of the lamps so once a few lamp failures happen,

Changing them all at the same time will be the way to go also do not turn them on till you have changed them all and they will all look the same when you are done changing them all out.


When you do turn them on they will all warm up at the same time and you should not be able to see a difference,,Let them run for a wile don't just shut them off after just a few minutes let them burn for a while.