Metal Toothed Separating
Metal toothed zippers are made out of aluminum, brass, pot metal, titanium. Metal zippers used to be the strongest zippers available, but not any more. Just like EVERY zipper, there are good ones & cheap ones!
I have picked these zippers for the quality! But all zippers wear out! Metal zippers always can use a little help. Use beeswax to keep them running well: a candle, or Burt's Bees lip balm, or a product made specifically for zippers. Rub a tiny bit on the open teeth, then open & close the zipper a couple of times.
When washing your garment, zip up the zipper & turn your garment inside-out. Try not to put ANY zipper in a hot dryer. The high heat shrinks the fabric around the zipper.
What the number means:
#3 - 3mm across the closed teeth. Not very strong but very cute in sweaters, tops or dresses.
#4 - I stock a few of these for bags. Not scratchy but strong for their size.
#4.5 - my favorite for sweaters in DK or heavier yarn.
#5 - STANDARD zipper in most hoodies or jackets.
#8 - what I'm starting to like in leather motorcycle jackets, vests, & chaps. Strong with a larger pull.
#10 - Carhardt's Jackets.