Hi, Team #KeepThemRuby!
We’re sure you’ve all been hanging by a (ruby) thread to hear what’s next in the conservation story of the Ruby Slippers!
In August, we told you that the Smithsonian’s Museum Conservation Institute team had identified the dye color Rhodamine B as the main colorant in the sequins, thanks to collaboration with research scientist Chika Mori from the Smithsonian’s Freer & Sackler Galleries. Identifying the dye is important because it will help the team choose the appropriate lighting to display the Ruby Slippers so they look their best to millions of visitors and also remain in their optimal condition for years to come!
Mary Ballard, Senior Textiles Conservator, observed something strange when comparing the color of Rhodamine B to the color of the slippers: Rhodamine B is a bright, somewhat flashy, purple-pink dye.

If the Ruby Slippers’ sequins really were dyed with Rhodamine B, how did they change color? What happened during their nearly eighty years of existence? Does exposure to light deepen instead of fade the color? Did the Ruby Slippers start out as pink!? 
Mary set out to find answers to these questions.

Pink or Ruby?

The sequins that make up our beloved Ruby Slippers are made of several layers of material: a nitrocellulose layer (similar to nail polish or varnish) on top of a gelatin core, with a layer of silver between.

The Rhodamine B dye is contained in the nitrocellulose layer. When dyes are dispersed in resins or varnishes such as this, they are more resistant to fading because they aren’t as exposed to oxygen, an element that causes color to fade.
Mary’s experimental work mixing Rhodamine B with a nitrocellulose lacquer in a film produced a darkening effect. Higher concentrations of the dye mixed into the film achieve a darker color. Additionally, the nitrocellulose layer causes the Rhodamine B to clump or cluster, which contributes to the richer color. Like magic, the pink dye then appears ruby!

Lights, Camera, Sunglasses!

“Light fastness” is a term used to indicate how resistant to fading a substance is when exposed to light. Determining the light fastness of the Ruby Slippers is a critical part of Mary’s research.
When a director shouted “Lights, camera, action!” on early movie sets, carbon arc lamps lit up the set. These lamps were so powerful they caused movie stars to wear dark glasses to protect their eyesight when the cameras weren’t rolling.
Mary concluded that the coloration in the Ruby Slippers appears to have survived intact, despite the hardship of the movie set’s lighting system and subsequent long-term low-level light display at the museum.
Good news for the Ruby Slippers and for all of us who love them!

Meet Mary Ballard, One of the Ruby Slippers Conservators

Mary Ballard, Senior Textiles Conservator at the Smithsonian’s Museum Conservation Institute, finds that the work there is never boring – there’s always an exciting and often unexpected new question to find answers to – and answers always lead to more questions.
Mary has always had an interest in fibers and color. She did some preliminary conservation work on one of the nation’s most treasured icons, the Star-Spangled Banner, the flag that inspired our national anthem and is currently on display at the National Museum of American History.
In addition to the Ruby Slippers, Mary is currently doing work for the National Air and Space Museum cleaning American aviator Wiley Post’s flight suit and remounting a fragment from a Civil War reconnaissance balloon.
You can find Mary wearing layers of clothing in the textile lab because it’s always kept at a cool temperature to preserve the materials they’re working with. However, these clothes can’t ever be wool or other animal fibers, in order to safeguard against wool eating insects – which do indeed live in the Washington, DC area!
“There’s No Place Like Home”
While at a silk conference in Hong Kong, Mary got some unexpected help on her Ruby Slippers research on the Rhodamine B dye. A senior scientist from the National Gallery in London referred her to a 1959 lecture on light fastness that just happened to be in the Smithsonian Libraries! In a way, Mary is just like Dorothy, whose journey to a faraway land led her to discover a power she’d always had back home.

Thank you, #KeepThemRuby backers, for being a part of this project and helping Mary do the important research needed to conserve this beloved American icon! We couldn’t do it without you!  
All images courtesy of the Smithsonian’s Museum Conservation Institute.