I've used chalk to whiten a black sight when conditions made a light colored front sight easier to see. Some have used the white typing correction fluid, Whiteout" for the same purpose. I was sighting in a rifle with a brass blade a couple of weeks ago and it was hard for me to see. I grabbed a black marker out of the range box and darkened the blade to make it more visible. I like a brass or silver on a original looking rifle. Having said that I have a TC Hawken that has a partridge style front blade and I really like it. It seems to work well with my older eyes.