Providing collection care, preservation and conservation treatment services to collectors and collecting institutions.
by Helen Alten
Once a year, does your museum staff don old clothing and grab dust rags, brooms and mops for the museum's annual exhibit cleaning? Get rid of the rags! Annual cleaning is best accomplished with a portable vacuum cleaner. The ideal vacuum features good dust retention, shoulder or back-pack strap, and micro-tool attachments for cleaning around artifacts in exhibit cases. Attachments for cleaning floors, ledges and shelves also are useful. Dust rags, brooms and mops are unnecessary if you have the right vacuum cleaner and micro tools.
If there is a possibility of pesticide dusts, lead dusts, arsenic, asbestos or other contaminants, you should be using a HEPA filter. A HEPA (High-Efficiency Particulate Air) filter traps 99.97% of particles 0.3 microns and larger. A 0.3 micron filter will capture soot, pollen, black and color copier toner, and the majority of atmospheric dust particles. ULPA (Ultra-Low Penetration Air filter) traps 99.99% of particles 0.12 microns and larger. Because of allergy problems, more and more HEPA and ULPA filters are becoming available.
However, not all HEPA filters are the same. If the filter does not sit tightly in the vacuum cleaner, it may not filter out as much as it purports. Chris Stavroudis (WAAC Newsletter, Vol. 19, No. 3) warns against using hospital-grade HEPA filters, which have HEPA-like or Gore-Tex microfilters. They are cheaper and their ratings look similar, but they do not provide the safety of other HEPA filters. Also note that home vacuums with "microfiltration bags" did not significantly cut emissions in 11 of 13 vacuums reviewed in Consumer Reports, January 1995. (This article also compares 34 uprights and canister vacuums, including the 13 vacuums without their microfiltration bags.)
Good dust filtration is not all you need to consider. Most vacuum cleaners are too good - their suction is too strong - for use in a museum. Nilfisk sells a Variable Speed Control Vacuum with four-stage filtration culminating in a HEPA filter good for 0.3 micron particles. You also can purchase an external rheostat to slow down a vacuum motor, creating lower suction. This may damage the motor, however, and void your warranty. For regular vacuum cleaners, opening a vent or drilling holes in the side of the tube will decrease the machine's suction. However, when using a fine filter to pick up toxic dusts, holes will negate your purpose.
The facts about and sources for 24 HEPA and ULPA vacuums are listed in the September 1997 issue of the WAAC Newsletter. Prices range from $229 to $1,695. The less expensive vacuums, such as the Fantom Fury, have the least suction. The August 1997 issue of Consumer Reports analyzes the cleaning and emissions of five vacuums. For museum purposes, deep-cleaning is not a virtue, since it suggests high suction. Excellent emission control, but only good deep cleaning were listed for the Miele White Pearl S434I ($850) and the already mentioned Fantom Fury F1005201 ($250). Not listed in the WAAC or Consumer Reports articles, the 8 lb. Atrix Jr. Vac, probably the lightest and cheapest ($150) of the high filtration vacuums, has a good level of suction for use around artifacts. Its filters are also less expensive ($3 to $8.75) than the vacuums reviewed in the published reports. Most replacement HEPA and ULPA filters are expensive ($70-125). Do not use less expensive bag filters for toxic substances, which require disposable, anti-dump canister filters.
The vacuum cleaner can become a versatile cleaning tool with the addition of micro-tools. Many conservators create their own micro-tools from plastic tubing and plastic eyedroppers. Small vacuums sold for cleaning computers have micro-tools that can be attached, using a plastic tube, to larger cleaners. These allow staff to vacuum around the smallest artifact without fear of sucking it up. If you do not work with micro accessories, be sure to put cheesecloth or nylon tulle (ballerina netting) over the suction end of your vacuum cleaner.
Finally, if you are unconvinced about the need to use fine filtration in your vacuum cleaner, conduct the following experiment: place a cloth diaper (or a piece cut from a cloth diaper) over the air exhaust on your vacuum cleaner. Clean a dirty area of your museum. Afterwards, examine the diaper. If it has trapped dirt from your exhaust, then you know you are re-depositing this material on your collection. Since it is better not to redeposit fine dust on a museum collection, consider switching to HEPA or ULPA filtered vacuums. More and more models are being made at all price ranges, making them accessible and affordable for most museums.
Helen Alten has written and lectured on preventive care techniques since 1986. She is an objects conservator specializing in treatments for historical, archaeological and ethnographic materials. Resources
Consumer Reports, August 1997, "Allergen-trapping vacuums," pp. 40-41.
Consumer Reports, January 1995, "Vacuum Cleaners," pp. 43-49.
Batyah Shtrum, "A Heap'o HEPA Information," WAAC Newsletter, V. 19, N. 3, p. 12.
Chris Stavroudis, "Health and Safety: Lead Sucks- HEPA Saves," WAAC Newsletter, V. 19, N. 3, pp. 12-15.
Catherine McLean, "Technical Exchange: Vacuum Cleaners," WAAC Newsletter, Vol. 13, No. 3.
Abbey Newsletter, Vol. 19, No. 1, May 1996 "Supplies and Services" column.
Vacuum cleaner distributor list available from Northern States