Laminate thickness is measured in mils (1/1000th of an inch). Large pouches come in 3, 5, 7, and 10 mil thicknesses. The small pouches are only available in 5, 7, and 10 mil thicknesses. It is customary to express the gauge of a pouch as the thickness of one of its sides; for example, a 10 mil pouch actually has a total thickness of 20 mils.
- Use 3 mil pouches for sheet protection. The finished product will still be very flexible.
- Use 5 or 7 mil to add a little rigidity to the laminated product.
- 10 mil pouches make great signs!
- If you are using small pouches to make up membership cards or I.D. badges, use a 7 or 10 mil pouch.
Gauge also tells you about the physical characteristics of your laminating pouch. For example, a 10 mil pouch can be 7/3, 6/4, or 4/6 construction. A 7/3 pouch has 7 mils of base plastic and 3 mils of adhesive, for a total of 10 mils per side. The 7/3 construction costs more than the others. A 4/6 pouch has a lot of adhesive, which may ooze out during the laminating process. Although all three of these constructions produce a 10 mil pouch, the 7/3 construction has more rigidity than the 4/6, and feels like a thicker pouch after it is sealed by lamination.
Here is a simple guideline for choosing the right gauge for large pouches:
- If you laminate a sheet of copy paper in a 3 mil 9" x 12" pouch, then hold it up by a corner, it will flop down over your hand.
- If you laminate a sheet of copy paper in a 5 mil pouch, then hold it up by a corner, it will bend down in a curve.
- If you laminate a sheet of copy paper in a 7 mil pouch, then hold it up by a corner, it will barely bend over.
- If you laminate a sheet of copy paper in a 10 mil pouch, then hold it up by a corner, it will stand up rigid.
Tip! You can make display counter cards and bulletin board pin-ups that don't flop over by printing on 60 lb cover paper, then laminating with a 5 (or maybe even a 3) mil pouch.