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Treatment: Reattachment

In order to stabilize fragile wall surfaces, gelatin treatment of detached and blistered finishes and grouting of loose mortars were conducted.  In areas of sooting, cyclododecane was pre-applied to the surface to circumvent staining.

The prepared gelatin solution (mixture of commercial gelatin, glycerin, isopropyl alcohol, and water) is heated in a water bath on site to be used with a needle syringe.  Depending on thickness, fragility, and finish type, a combination of hot and cold gelatin is injected to reattach delaminating, detaching, and blistering finishes.  A warm liquid 5% gelatin solution is used for most thin layers under 2mm, while a cold, gel-phase 10% solution is used for thick layers over 2mm.

Gelatin solution is injected behind the surface finish and set down with moist sponge.    
 

In order to avoid staining in areas of heavy carbon sooting, cyclododecane (C12H24) is used before gelatin treatment.  First developed for the field of paper conservation in order to prevent ink from bleeding during wet treatment, a hydrophobic film of cyclododecane applied on the surface blocks the migration of water from the gelatin solution.  When the gelatin solution is applied, the movement of water and gelatin is limited to the subsurface layer, minimizing staining.  The white solid cyclododecane then sublimates after application, leaving no visual trace behind.

In the past, cyclododecane was applied in liquid form by brush after melting from powder on site.  While the brush application of liquid cyclododecane has been effective for smaller areas, it was found less effective for large areas as it tended to cool and solidify quickly requiring rapid and repetitive application.

In the 2010 season, a spray form was commercially available and applied instead, allowing the team to cover large fragile areas with minimal surface damage.  The cyclododecane is sprayed on the surface and its solvent/propellent immediately evaporates upon release from the canister.

 
After initial application, cyclododecane sublimates without a trace.