Squealing Brakes

Two months ago, I changed the front wheels brake pads of my Honda Civic automatic 1993. But since then, it produces a squealing sound whenever I use the brakes for the first km of driving but thereafter, there is no sound. The squeal is louder during cold weather.
The mechanic said it normal as the contents of the brake pads contain metal which causes the sound. Is this true?

Reply:
There are several causes of brake squeal, mostly due to the brake pads vibrating because of rust on the pad backing plates or rust on the brake dust on the pads themselves.
In your case, it may be rust on the brake discs as a very thin layer of rust develops on the discs when the car is parked overnight, and on initial application of the brakes, this is causing the pad to vibrate. After a couple of applications, the layer is removed and the disc is smooth again and the squealing stops.
One solution is to remove the brake pads, clean the back and apply a thin layer of graphite-based grease on the back. The will reduce the chances of the pads vibrating and possibly eliminate the squealing altogether. Very hard brake linings can also cause squealing but that would happen almost every time you brake and not just in the morning.