Laminators will not laminate without laminating material.
The material used consists of various types of plastic. They vary in thickness, in durability, and in appearance. They come in rolls of various width and length depending on the application and the volume of laminations to be done.
The thickness of laminating film is measured in "mils" - thousandths of an inch. It's also referred to as "weight". Typical thicknesses are 1.5, 3, 5, 7, 10 and 15 mils. The choice depends upon what the laminated item will be used for. Something that's going to be handled a great deal - such as ID badges - needs to be quite thick, whereas something that will be left alone most of the time, such as a poster to be hung on the wall requires a correspondingly lighter film.
Note that the total weight for a given lamination is TWICE the weight of the film (it has two sides, after all) plus the weight of the laminated item. Usually this doesn't matter but mailings, for instance, need to be concerned with this.
Suppliers of the films will have good documentation on weights and requirements.
Normal laminating is done with material that's as clear as possible. This is "standard clear". A "matte" material - slightly frosted - is used to simulate the photographic matte finish. Material with significantly reduced glare & reflections is "Satin". There is a "scratch-resistant" film available: it isn't necessarily thicker but is very hard once it's cooled. Finally there is "crystal" finish - it feels faintly sandy and is for special effects.
Other sorts of material are available for really special requirements, and coloured laminates can also be had.
While selecting the film with an appropriate weight is important, using it at the correct heat is also a requirement. Inappropriate material or improper heating can result in defects in appearance and durability: very simply put, if the film is heated too much it will melt! But there are two common possible defects that can also occur (there are others such as can be caused if the supply rolls bend but they apply mostly to industrial-size operations):
The following guide should prove sufficient to avoid these two problems. Remember that the weight given is TWICE the actual weight of one thickness of film.
3mil film: low-med heat
5mil film: med heat
7mil film: med-high heat
10mil film: high heat
Anything above 10-mil is in industrial territory.
Although most manufacturers of film will state that their products are "standard", if necessary there are some objective standards to check with of necessary. These include those available at Labthink or the U.S. General Services Administration.