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Wet erase markers are used to write on transparencies, such as those used with an overhead projector. They provide a bright, clear image that won't fade or bubble under the intense heat of the projector's lamp. These markers are also known as transparency or overhead markers.
Transparency markers are composed of water, propylene glycol and dye. They are water soluble and have no odor. Because of their presence in the school system, these markers are non-toxic and most are washable.
The wet erase marker got its name because the ink has to be removed using a damp cloth, unlike the dry erase marker, whose ink is removed with a dry cloth. Many teachers and students prefer to use a spray bottle and paper towels to thoroughly clean the transparency and overhead projector after use.
Overhead markers, unlike dry erase markers are only intended for use on acetate, film or non porous surfaces. They contain water-soluble dyes that will penetrate and stain porous surface. Wet erase markers won't bead or smudge on smooth surfaces.
Most of these markers have a chisel tip. This means that, depending upon how you hold the marker, you can write with a thin or wide stroke. Since many wet eraser markers are used to fill in charts and graphs on transparencies, the fine tip is a major asset. For those who prefer it, though, there are a few suppliers of medium point overhead markers.
There are several suppliers of wet erase markers. The most popular supplier is Vis-a-Vis, who sells their products through many diferent ofice supply stores. These types of markers are manufactured in several colors to include red, black, blue, and green. Although they are less popular, you can also find them in neon colors. The Board Dudes Direct is one of the few manufacturers of medium point wet erase markers.
When not in use, wet erase markers should be stored in a horizontal position, with the cap on. If stored with the capped end downward, the ink will over-saturate the tip. If stored with the capped end upward, the tip will dry out. Store the markers in a cool, dry place.
Most overhead markers are washable. To remove transparency marker stains, saturate the clothes immediately with stain remover. Allow them to pre-soak in a washing machine with OxiClean® and cold water. Wash as you normally would. Verify that the stain is removed before drying, as it will cause the stain to set.
@robbie21 - I've done that, too! I teach English, so we do a lot of grammar on the overhead projector. (Because the combination of grammar--boring--and me turning my back on the class is a recipe for trouble!) I like to write sample sentences on a transparency with a sharpie marker, so it's permanent. Then we mark it up with a dry erase marker, and I can erase it for the next class and not have to write the sentences again.
I also like the ink jet transparencies. With those, I project onto the dry erase board and write directly on the board. The kids thing it looks funny when you turn off the projector and just have commas and whatnot on the board!
You can actually use expo markers or other dry erase markers on a transparency. It doesn't show up as well and it's not as permanent, but it's nice if you're just doodling something for the kids. Wet erase can be kind of a pain!
On the other hand, dry erase markers stain *forever*. I've never had to try to get out wet erase stains, but dry erase marker is impervious to all my usual tricks (including hairspray, which works great on regular ink).
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