Mist Consolidation
Mist consolidating various media water-based media on a glass substrate, butterfly wings, and chalk on chalkboard painted substrate. Image courtesy of Karissa Muratore. Seminar taught by Julie Ream, Paper Conservator in private practice.
Mist consolidation is most often used for consolidating powdery paint surfaces that require greater control due to the surface’s friability or if the surface appearance (e.g. saturation and/or gloss) are readily affected by the application of a consolidant by conventional means. The technique’s slower delivery matches the slow capillary action of an object, improving the penetration and resulting in less skinning and surface changes. One advantage of the technique is that it allows for progressive build up of consolidation layers.
The technique has been adapted for various applications on paper artifacts including removing discolored fixative and resizing paper. More recently, conservators outside the discipline of cellulosic materials are using the technique to consolidate reverse paintings on glass, natural history specimen, painted cardboard, drawings on chalkboard, or any other friable materials – such as butterfly wings! I was able to attempt consolidation on a butterfly wing in the practical session of the seminar when participants were able to test various nebulizers and consolidants.
A nebulizer, a device that converts a liquid to a fine spray (1-10 micron droplet size), is used during consolidation that aerosolizes liquid consolidant. Nebulizers produce a mist of fine particles that penetrates deep into the lungs; thus, respirators must be worn to prevent inhalation. The ideal consolidant is one that has a high molecular weight but low viscosity (e.g. Aquazol 500). Oftentimes, gelatin or Klucel G is used in very low concentrations (0.25-0.5% solutions).
Testing different nebulizers with Jennifer Myers, WUDPAC Paintings fellow. Image courtesy of Karissa Muratore. Some drawbacks of the technique are that it can be time intensive, particles can be dislodged due to force of air flow, and that the consolidant can begin to foam up in the jet nebulizers. To prevent dislodging particles, the nebulizer pen can be held 90 degrees to the surface or the object can be pre-humidified.
To encourage bonding, pressure can be gently applied using Teflon micro-spatulas or a figure through silicone release Melinex (silicone coated stabilized polyester film).