A simple vacuum revolution

 I have recently had an 'Aha!' moment. I have always struggled with the small attachment tool for vacuuming. Untill now!

You know that wonderful, handy and inexpensive micro-tool that comes with the many small changeable tools. I realize that part of my struggle when using it, was the narrow-long plastic tube that linked the small attachment brush to the vacuum cleaner connection. It always seemed like I needed a third hand,  because two hands were needed to manipulate the tubes, but one was still needed for the tweezers, the micro-tool and the like.

Why does this narrow tube need to be so long, I thought? Really a new thought. The innovation is just to  cut the tube. So I did this, and Voila! Now less of the tube to manipulate, it simply connects the two sections of the micro-tool. Now, one hand is free to hold the vacuum attachment and the other for other tools that I might need, such as tweezers.

A Low-Tech Treatment for Small Areas of Visible Mold

The humidity many of us have experienced this summer due to torrential rains and heat sweeping across the country can easily lead to mold growth. Now in the wake of Hurricane Florence mold will be rampant as the flooding recedes. (For more on freezing see our earlier post.) It's important to be vigilant by monitoring humidity levels throughout your institution or home to prevent excessive moisture levels. Mold is not only a hazard for objects, it's also a danger to people.

If you've got a big mold problem, first fix the source of it and then call in professionals to remediate it. Poor drainage, foundation or wall cracks, leaking roofs or plumbing, lack of sufficient ventilation or air-conditioning all contribute to the spread of damaging mold.

If you have visible mold in less than 10 continuous square feet, you may be able to remediate it yourself with dehumidification and a low-tech water trap attached to your vacuum to capture the spores.

The water trap can be made of any glass or jar. The one we use in the studio is in the image below. It is important to ensure that it is well sealed around the openings and the tubes. Ethafoam (a strong, resilient, medium-density, closed-cell, white polyethylene foam which is acceptable for use in the preservation of objects) is really helpful for this. Gwen even carved out a stand for the glass to ensure it would not fall over. The other critical aspect is the ends of the two tubes inside the glass are above the water line. It is the vacuum's suction that forces the mold spores into the water i.e. trap, while not traveling into the vacuum cleaner.

The above photo illustrates how the water trap is connected to a vacuum. The right hand hose (with the blue end on it) is the one used to suck up the mold.

When finished, thoroughly clean all of the associated tools, mark them and save them together, including brushes.

It's very important to contain the spores, not spread them around (which is what regular vacuuming will do). Here's a step-by-step guide to what to do next and don't forget to wear an approved N95 respirator, gloves, and eye protection!

Captured mold

Resources

Gwen Spicer. When Water Strikes, It's a Freezer to the Rescue! March 2018.
Ibid. Mold on Pastel Portraits, why it grows and how it can be prevented. January 2017.
Idid. Mold in museum collections is the environmental "canary in a coal mine". September 2014.

What are Flexible Magnets?

You know them and we bet you even own a few! We're talking about flexible magnets, also sometimes called refrigerator magnets, which first appeared as a type of ceramic magnet in the 1960's. 

Because they're made with flexible resins and binders (synthetic or natural rubber) this type of magnet can be produced as 1) extruded magnetic profiles that are usually coiled or 2) in sheets, resulting in a wide variety of options and properties. For example, extruded flexible magnets are often found on shower door or refrigerator closures. Magnetic sheets, on the other hand, can be cut into all sorts of shapes and sizes, and are what you find holding that souvenir of your summer vacation to your refrigerator door or office filing cabinet.

When flexible magnets are extruded, they pass through a line of powerful cylindrical permanent magnets or a rotating magnetic field. This step allows for the creation of a wide variety of options. For instance, they can be formed to have holding power on both sides, or only on one side. 

The most commonly arranged magnetic poles occur in an alternating line format on the same surface plane (NSNSN or SNSNS). An interesting phenomenon occurs when two layers are slipped slightly on top of one another: they both repel and attract as one slides across the surface of the other. One side of the flat surface is more magnetic (has an increase in holding force) than the other. This arrangement of polar direction is called the Halbach Array. It is this alternating polarity that creates modest attraction (fig. 1). 

Figure 1: A cross-section of a Halbach array with the alternating poles that create a stronger magnetic
field on one side and a weaker one on the other.

The most common style used in museums is the multi-pole on one side. In museums, flexible magnets are commonly used to attach accession or object numbers in documentation photography, for overall humidification as a substitute for weights, holding wrapper enclosures closed, and mounting of lightweight flat artifacts. Their continuous magnetic field is ideal for overall support; their low pull force, however, does not allow them to support heavy or thick items (Schlefer, 1986; Stenstrom, 1994; Braun, 2001; Keynan et al., 2007; Vilankulu, 2008; Heer et al., 2012; Migdail, 2013).

The pull force of flexible magnets is quite weak, and they have low magnetic strength when compared to a non-bonded magnet. Today, the flexible-style magnet is also formed with neodymium (further described in the following section), creating a much greater pull force. Thickness of the flexible material is in direct relation to the pull force of the magnet. Manufacturers specify pull force in pounds per square foot. Pull force is related to thickness; the thicker the sheet, the stronger the magnet. A flexible magnet .04 cm (.015 inches) thick has a pull force of roughly 40 pounds per square foot (0.278 PSI) while a flexible magnet .08 cm (.030 inches) thick has a pull force of roughly 85 pounds per square foot (0.59 PSI). No other magnet type has such clear-cut specifications; therefore comparing flexible magnets with others is not easily transferable (table below).

Table: Thickness of the flexible magnet and the pounds per square inch of pull force

Thickness	Approximate pounds per sq. ft.	Pounds per square inch (PSI)
.012	30	0.2
.015	40	0.278
.020	60	0.417
.030	85	0.59
.060	144	1

Flexible magnets are very susceptible to demagnetization, especially when in contact with other stronger magnets and with other similar flexible magnets (fig. 2) (Livingston, 1996). They also appear to lose their magnetization over time, likely due to proximity to other magnets. Flexible magnets are less susceptible to demagnetization by their Curie Temperature. When used in a situation where strength is needed, they should be checked occasionally.

Figure 2: The parallel rows of the flexible magnet visible with a
'magnetic viewing film (left). The same parallel rows disrupted
when exposed to a rare-earth magnet (right).

Flexible, bonded type magnets are conducive to creating large area pressure type systems. These ferrite-bonded magnets are weak, but to increase the strength, the polar directions are arranged as in a Halbach Array during manufacture. It is this alternating polar direction that provides gentle pressure, evenly dispersed over an entire surface. Conservators use the standard magnetic orientation of a magnetic force on one side. Sheets can vary in alignment when placed together and should be trimmed as a pair. Their strength can be increased somewhat by using both thicker flexible magnets and a related gauge of metal (Spicer, 2014). A second layer of flexible magnet placed on top does not add to the pull force of the first layer, due to its particular alternating polarity.

The addition of pressure created by the pull force can both introduce and assist in the removal of moisture during humidification of an artifact. An artifact sandwiched between absorbent materials is given overall pressure either between two flexible magnets or a top flexible magnet layer above and a steel plate below. The presence of the sandwiching method has been noted to slow drying time (Blaser and Peckham, 2006), but the benefit of not having to lift heavy weights offsets this.

Learn more about magnets and their many uses in the new publications Magnetic Mounting Systems for Museums and Cultural Institutions. Available for purchase at www.spicerart.com/magnetbook.

Resources

As a conservation tool, flexible magnets have been successfully used for a wide range of applications, including during humidification of paper and book repair as a substitute for weights (Brooks, 1984; Stenstrom, 1994; and Blaser and Peckham, 2006); an embellishment attachment with two layers of flexible sheets (Braun 2001); and mounting (Keynan et. al., 2007; Heer et al., 2012; and Migdail, 2012).

Beware “Fake” Dust Masks and Respirators

As part of a FEMA team deployed to Puerto Rico, Gwen is volunteering her conservation expertise this spring to cultural institutions that continue their recovery from last fall’s devastating hurricanes. She and her colleagues use dust masks and N95 particulate respirators on a daily basis to protect themselves from a range of non-oil based airborne particulates, including mold.

In the warm and humid environment of Puerto Rico, mold grows quickly. In addition to the damage it causes to objects, textiles, and paper-based materials, it has the potential to cause health problems. Allergic reactions are common and can be immediate or delayed. Respiratory protection is essential and the safest, most reliable gear is approved by the National Institute for Occupational Safety and Health (NIOSH), the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness.

The N95 respirator is the most common of the seven types of particulate filtering facepiece respirators and filters at least 95% of airborne particles but is not resistant to oil.

To their surprise, the team found that some of the dust masks in use are not approved by NIOSH. Rather, they are marketed as NISH-approved, which is not a legitimate designation.

Gwen urges you to check your dust masks and respirators to ensure they are N95 NIOSH approved and discard those that are not.

Resources

NIOSH is part of the U.S. Centers for Disease Control and Prevention. You can learn more about NIOSH at https://www.cdc.gov/niosh/about/default.html

Respiratory Protection for Residents Reentering and/or Cleaning Homes that Were Flooded  https://www.cdc.gov/disasters/disease/respiratory.html 

Training videos for respirators  (available in Spanish and English) https://www.osha.gov/SLTC/respiratoryprotection/training_videos.html 

Una Breve Guía para el Moho en el lugar de trabajo (available in Spanish and English) https://www.osha.gov/dts/shib/shib101003.html 

https://www.cdc.gov/disasters/disease/respiratory.html