How to prevent plastic roll static shocks?

September 25, 2008 1:33 PM

How can I ground a large roll of plastic wrap to prevent static electric shocks when unrolling it?

At my place of work (a spa) we have a large roll of plastic, perforated into sheets that are used in some treatments. Every time a sheet is unrolled and torn off, the person doing so gets a good shock from the static electricity. Is there any way to prevent these shocks?

The plastic is wrapped around a cardboard tube, which is strung on a wooden dowel. The dowel sits into a painted metal frame which is mounted on a wood trim piece in the staff room. It's high up, so the girls stand on a metal-framed stepladder with plastic steps and with plastic feet on one side, a metal bar on the other. The ladder sits on the carpeted floor while it's used. We're up in the mountains at about 9000 feet above sea level, a very dry climate, which seems to contribute, especially during cold weather.

The whole apparatus is pretty close to plumbing and electrical boxes, conduits etc, if that helps for grounding points.

posted by attercoppe to grab bag (7 answers total)

You can't easily ground it. The problem is that the plastic is a good insulator and while you're unrolling it electrons stick in place.

If you unroll it and reroll it with a conductor (foil or anti-static plastic or wires or something) you will solve the problem, but you'll get zapped a bunch unrolling it. :D

Alternatively doing this in a really humid environment will help.
posted by aubilenon at 1:44 PM on September 25, 2008

...bear in mind that perhaps "ground" is the wrong term. I'm not too highly knowledgeable in electrical things. Maybe a (electricity/static/voltage/whatever) sink is what we need? Something that would draw off the charge either from the air or the plastic and either ground it or just disperse it elsewhere. (Or is that just what a ground is?)
posted by attercoppe at 1:49 PM on September 25, 2008

Try grounding tinsel. I've seen it used in print shops to prevent mylar from adhering to machinery. You could let it drape over the top of the roll, and ground it to the stand.
posted by kuujjuarapik at 1:51 PM on September 25, 2008

Yup, kuujjuarapik. Normally it would be set above or below the dispenser and run the width of the sheet, just where the material leaves the roll.
posted by StickyCarpet at 2:05 PM on September 25, 2008

Have you considered using a humidifier in the staff room? If you can raise and maintain a relative humidity of 55% RH or higher, you can eliminate static electricity.
posted by RichardP at 2:25 PM on September 25, 2008

Grounding Tinsel rocks for this application - you just stretch a bit of it across where you pull the sheet off the roll, so that it "scrubs" the sheet as it pulls off the roll. It works best if you use two pieces to ground both sides of the sheet (ie feed the sheet between two pieces of tinsel).

You also have to ground the tinsel - run a grounding wire from the tinsel to a suitable grounded contact in the room - metal plumbing works well, metal beams or structural members also work.
posted by Crosius at 2:39 PM on September 25, 2008

Grounding tinsel is the solution, but if you want a cheap quick fix you could fashion your own tinsel from some aluminum foil. Pull out a sheet that is as long as the roller. Fold over the edge about 1 inch wide and keep folding it over until you have a long strip that has some strength. Then unfold the last fold to leave a single layer about an inch long. Use scissors to make cuts into the last inch so you have a lot of strands like the end of a broom. Stretch the strip across the plastic roll loosely and tape it to the frame on both ends so the strands rub on the plastic as it it unwound. As others said above, you may have to ground the tinsel to a plumbing pipe.
posted by JackFlash at 3:02 PM on September 25, 2008