Getting your classroom posters, charts, bulletin board sets and children's art work laminated is something all teachers do. Knowing where to go for the best lamination services, and what good lamination is, many teachers don't know. First off, we are talking about hot lamination with a machine, and not contact paper. That's something different. Once a poster or chart is laminated, it will last for years. It will be very difficult to rip or tear. This is why teachers laminate. It pays to spend a little bit extra on the lamination, so that their classroom decorations last.
So, here are a few things to know about your local lamination services. There are different grades of lamination paper, different brands and different thicknesses. These are the three most important things to know about laminating. The grade of the paper has to do with how free of imperfections the paper is and how clear. A cheap grade of paper has imperfections and isn't as clear as a high grade of paper. It's like a camera lens. An expensive lens has better glass and less imperfections, so that you get a better picture. If you want a nicely finished piece of lamination, use a high grade paper. In my opinion, Opticlear by USI is the best grade and brand of laminating paper.
The thickness of the paper is also very important. Ask the store or place you are getting your posters laminated what thickness they are using. One place might be charging half the price of another place because the lamination paper they use is half the thickness. Some places use 1.5 Mil, while others use 3 Mil-twice the thickness. Don't be fooled by cheap laminating prices. If they are using very thin paper, it may not be worth going there. You want a decent thickness to the paper, and a good brand. I recommend 3 Mil thickness.
Another thing to consider when getting your posters laminated is the size. Most places will not laminate anything wider than 25". This is the maximum width of most retail store machines. The length of the item usually doesn't matter. It can be many feet long, and will just feed through the machine. There is a trick to laminating items that are wider than 25" even if it won't fit through the machine. The laminating service place can fold your chart, pass it through the machine, then fold it the other way and pass it through a second time, so that both sides are will be laminated. There will be a thin crease where the fold is. This is the trick to getting extra wide posters laminated. A good laminating place will know how to do this.
Also make sure you laminate only paper and there aren't lots of thick things stuck to the paper like wood or jewelry. I see this all the time in my shop. Teachers bring in their children's art work or Sukkot posters with lots of items stuck to the paper. This makes it difficult to feed thru the machine. If it does go thru, there will be air bubbles around the thick items on the paper. The finished product might not look that great. A Better solution sometimes, is to take the pieces off the paper, laminate it, then glue them back on after the paper is laminated.