Elaine Summerhill
In photography, lighting can impart a color cast based upon the type of light
which is being used. When light hits an object, that object absorbs some of the
light (particular part of the color spectrum).  White is not a color; it is
achromatic and most of the color spectrum is reflected back.  Red suits are
seen as red because the red part of the spectrum is reflected back. And, black
is black because all light, the entire spectrum, is absorbed and none of it is

If one is using natural light for photography, depending upon the time of day,
one can get either a warm or cool effect.  Sunrises & sunsets are red
because we are seeing the long rays of the red spectrum.  Film shot at those
times usually have a reddish (warm) cast to them because of those same long
rays.  Incandescent lights also produce a warm, yellow or red cast.  One way
to combat the cast is to use a blue filter.  Conversely, if you are getting a
blue or green cast, one would use a daylight filter. 

So, to make a long story shorter, it makes perfect sense to me that if you are
showing a Westie that has any wheaten (yellow, fawn, etc.) in its coat, that
wheaten will show up much more under incandescent lighting as the wheaten color
will reflect more of the yellow-red part of the spectrum.  The same dog could
be shown under cool light conditions, such as at noon outdoors, and the coat
will appear white because the green-blue part of the spectrum offsets the

Now then, having had parents who worked in a laundry soap factory, I've
learned a little bit about bluing agents.  Studies have been done by laundry
soap manufacturers which show that true white isn't as appealing to people
as white with a slight bluish cast.  To make 'whites whiter', many
detergents now have bluing agents in them.  However, many of those agents are
made with fluorescent dyes (optical brighteners that are primarily reddish blue
or violet tints) and those dyes convert UV (ultra-violet) light to visible

The author can be contacted at
Elaine @ DM Greyhounds