Interesting to hear of your spark-as-you slide problem, which I passed on to the Institution of Electrical Engineers Consultants mailing list. Comments back mainly suggested the need to keep relative humidity in the tube above 50%, which it should not be too difficult for you to do. 

Earthing the metal rivets - as you propose doing - will not mean  that your technician will pick up less electric charge than before, but  that he discharges it in a regular manner each time he passes over a set of rivets. Hopefully this will be less painful than going past several sets of rivets until a discharge takes place to the first rivet that offers a good discharge path to earth.

Without the rivets, your technician would have accumulated charge until he got to the bottom, when he would have discharged in a more spectacular manner to the nearest earthed object. It would certainly be a hair-raising experience in the literal sense of the term. 

If the technician were to land on an insulated mat he would retain his charge. To avoid any shocks on leaving the mat, he should seek to gently discharge himself first by means of some sharply pointed metallic object held in the hand. A spear or dagger would do, but might not be acceptable from a museum security point of view.  The sharper the radius of curvature on the object the better: therefore a needle or tiepin might be better than even the sharpest spear. 

If the mat were metal, insulated from ground, the technician would share the charge with the mat  and the potential of the mat would rise. Given now a succession of schoolchildren following in the technicians wake, and supposing that they all remained on the mat, the potential would continue to rise. All the accumulated charge would be discharged via the first person to step off the mat. So it is good to hear that your structure is well earthed!

What a shame your electrostatically charged technician will not be given the chance to demonstrate your slide as a new form of "hands on" science. I had visions of sensitive CCTV cameras in the tunnel displaying the effects to those waiting to go down the slide. If you had fitted small discharge tubes on the outside connected between each rivet and ground these might  have glowed as each sliding visitor went past. The brightest glows would be achieved by the technician, although experimentally minded youngsters might find have found the right kind of charge generating interface to place between themselves and the tube and thereby achieve an equal performance. 

Bearing in mind that a cat under dry conditions can produce a spark when stroked that can be easily detected on a small radio receiver, we may imagine the effect if cats were to take to your slide. Once word got around, the museum cat and friends would sneak in of an evening to practice their slide and spark routine. Clearly the late lamented Herbie, a Museum Cat well known to this list, would have enjoyed the fun had he been alive.

How your shocking slide would have delighted the Victorians! The waiting crowd would have linked hands, with one person touching the landing platform,  with the far end of the chain touching an earthed object, in order to experience the shock each time your technician descended. Today however safety dictates that you have to restrict your slide to its original purpose. What a pity! 

Frictional generation of static electricity is of course a problem in industry, especially with moving powders or liquids, so you are quite right to be concerned about possibilities. Several classic cases come to mind. Supertanker explosions in the 1960's were caused by water droplet charging when water sprays were used to clean out oil tanks. Windblown sand over Rommel's Afrika Korps tanks in the Western Desert in WWII caused a build up of charge which discharged when moist ground was reached, with sufficient energy in the spark to ignite petrol vapour and set the tanks on fire. Even steam jets are capable of causing significant build up of charge. The London Polytechnic in the 1840's exhibited a large Armstrong "Hydroelectric" generator with 42 steam jets that was quite capable of knocking out a large Newfoundland dog. A similar "Hydroelectric" machine was exported to the US at about the same time. (A single jet "Hydroelectric machine" -just a boiler and nozzle standing on four glass insulating legs can be seen in the Newcastle upon Tyne Museum of Science and Engineering.)

Wishing you a spark free future!

Antony Anderson
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http://museum-security.org/denney/index.htm

----------
From:   Sheila Darr[SMTP:[log in to unmask]]
Sent:   02 April 1998 17:07
To:     [log in to unmask]
Subject:        Update on slides and static electricity

Thanks to all of you who've responded to my query about our
shocking slide! The range of suggestions --both on and off
list--was fascinating. Special thanks to all of you who
thought beyond the obvious!