A Preliminary Study on Fig Preparation for the New Museum Exhibit

One aspect we want to experiment with is the dehydration process. Raw figs are composed of approximately 80% water and 20% carbohydrates. We want to see if we can replace the water with another solvent – acetone or ethanol - and whether this would increase the stability/firmness of the fig. Further, if we impregnate the fig with chemicals, would the dehydration step allow for better saturation of said chemicals into the fruit? Below you can see that in experiment 1 through 3, we will keep the first and third stage consistent, while comparing the three dehydration stages.   

Another interesting avenue we are exploring is introducing PEG into the fruit. PEG, polyethylene glycol, has been used in the conservation field primarily for waterlogged wooden artifacts. Waterlogged wood refers to a wooden object that has been immersed in water for an extended period, resulting in alterations to its original function, purpose, or appearance. An example of waterlogged wood is the salvaged remains of a sunken ship. In quite simplified terms, the application of PEG to these objects works by slowly replacing water molecules with PEG molecules, which will in theory preserve the structure and integrity of the waterlogged artifact. In addition, PEG has been used in other institutions for taxidermy preparation (primarily in Europe), however, not much has been published about this use.

We are intrigued by the possibility of the fig fruit exhibiting behavior akin to waterlogged objects when introduced to PEG. Furthermore, there are PEG compounds with different molecular weights. In principle, smaller molecular weights may increase the penetration. Our aim is to understand how the molecular size of various PEG compounds influences their penetration into the fig. As such, we will start with smaller molecular weight compounds and increase the molecular size until saturation. Lastly, our research uncovered a novel product, SP-11, positioned as an alternative solution to PEG for waterlogged wood artifacts. Similar to PEG, SP-11 operates by displacing water molecules and preventing structural collapse or shrinkage. However, it is marketed to have quicker penetration times, and not add weight or darken the surface. Below you can see that in experiment 3 through 7, we will keep the first and second stage consistent, while comparing the third stage (impregnation).

Finally, our experimentation will encompass various drying methods - air drying, freeze drying, and freezing followed by air drying - to determine which produces the best result. Notably, freeze drying after PEG impregnation in water-logged wood has demonstrated a reduction in shrinkage after drying. This technique, put simply, involves freezing the specimen (resulting in ice formation within the object), followed by the removal of the ice under vacuum through sublimation.

Pairing freeze drying with PEG is common. The freeze drying reduces stress on the cell walls, while the addition of a protectant such as PEG, limits the damage to the structure during the freezing process. Additionally, we were concerned with figs dehydrated with ethanol/acetone or impregnated with SP-11 being placed in a freeze dryer, as we did not have the proper equipment to properly evacuate the solvent while maintaining a low enough pressure to avoid solvents melting. Therefore, only figs in an aqueous solution and PEG will be freeze dried.